Every year, video games become more realistic, the characters more lifelike. Sometimes, it can even be hard to tell the difference between the latest Hollywood thriller and the best of virtual reality. But have you ever considered the possibility that what we think is real life is actually a video game? Surprisingly, philosopher Nick Bostrom has argued that it may actually be highly probable that all of us are living in a large-scale computer simulation right now! If Bostrom is right, it seems like pretty much everything we thought we knew about reality is in fact false.
Bostrom’s argument is centered on the idea that highly advanced civilizations might develop the technology to create such simulations, and if it is possible and they are willing, then it turns out we’re probably just like those characters in your favorite video game. Why? Well, even if only a small number of civilizations reached such a high level of technological advancement, they’d be positioned to create many, many virtual worlds, raising the chances we’re in one of those worlds rather than the ordinary reality we take ourselves to be part of.
In today’s reading, we’re going to explore similar themes, not just about the existence of the world outside our heads, but whether we can know anything at all. Specifically, we’ll be focusing on an argument for global skepticism developed by a medieval Islamic thinker, al-Ghazālī.
Abū Ḥāmid al-Ghazālī (1058-1111) was one of the most prominent jurists, theologians, and mystics of Islam. During a period in which the Arabic tradition of Aristotelian philosophy (falsafa) had reached its formative years, and coinciding with a systematic development of philosophical theology (kalām), medieval Islamic thought oversaw important intellectual developments concerning the roles of faith and reason. Through engaging these different schools of philosophical thought, al-Ghazālī played a pivotal role in the critique of the falsafa tradition and the development of kalām. But following a spiritual crisis in 1095, he abandoned his academic career for a life of contemplation and inner seeking.
In his famous autobiography, The Deliverance from Error, al-Ghazālī outlines the nature of his spiritual and intellectual journey, beginning with his infliction with doubt. It is his struggle with doubt or skepticism which is the topic of this reading. If you’re interested, the full text of al-Ghazālī’s Deliverance can be found here.
Epistemic Certainty – a type of certainty about a belief that is fully supported by the evidence, so much so that the belief is guaranteed to be true. For example, knowing that 1 + 1= 2 is epistemically certain, because once you understand the terms of the equation, it is evident that it must be true.
Psychological Certainty – a type of certainty about a belief based on one’s subjective feeling of conviction, whether or not it’s true. For example, you might feel sure you saw a ghost, but that feeling alone doesn’t guarantee it happened — unlike epistemic certainty, such as knowing 1 + 1 = 2, which is guaranteed by the strength of your evidence.
Global Skepticism – the position that we do not know anything at all, so we should be skeptical of all knowledge claims.
Mystical Experience – a profound experience of the divine which brings one into a sense of union with God.
Al-Ghazālī begins his intellectual journey by laying out his desire and yearning for genuine knowledge and understanding of ultimate reality.
The Deliverance, sections 12-14
Know then, my brothers (may God direct you in the right way), that the diversity in beliefs and religions, and the variety of doctrines and sects which divide men, are like a deep ocean strewn with shipwrecks, from which very few escape safe and sound. Each sect, it is true, believes itself in possession of the truth and of salvation, “each party,” as the Koran saith, “rejoices in its own creed”. […]
The thirst for knowledge was innate in me from an early age; it was like a second nature implanted by God, without any will on my part. No sooner had I emerged from boyhood than I had already broken the fetters of tradition and freed myself from hereditary beliefs. Having noticed how easily the children of Christians become Christians, and the children of Moslems embrace Islam, and remembering also the traditional saying ascribed to the Prophet, ‘Every child has in him the germ of Islam, then his parents make him Jew, Christian, or Zoroastrian,’ I was moved by a keen desire to learn what was this innate disposition in the child, the nature of the accidental beliefs imposed on him by the authority of his parents and his masters, and finally the unreasoned convictions which he derives from their instructions.
In this passage, al-Ghazālī makes two important points that are valuable for all of us budding truth-seekers. First, he speaks of his natural yearning for comprehension or knowledge of things. Although he suggests that he is gifted with this natural inquisitiveness, and even if we are less gifted in this sense than him, we’d do well to nurture or perhaps simply return to this natural wonderment as we engage in philosophical inquiry; let it drive our intellectual pursuit!
Second, in citing a tradition of the Prophet Muhammad, al-Ghazālī notes that human beings are born with a shared human nature (fiṭra) but that it is typically our cultural environment that shapes our beliefs, morals, and behaviors. There are many different religions and creeds, but where they conflict, only one can be right! Even so, the least we can do is strive to discover the truth despite our religious and cultural limitations. Al-Ghazālī thus instructs us toward the intellectual virtue of sincere truth-seeking, irrespective of our initial starting points. It is this intellectual virtue that is the springboard for al-Ghazālī’s skepticism.
Al-Ghazālī’s next step is to get clearer on precisely what it is he is seeking: a complete comprehension of things in themselves and how this is to be obtained.
The Deliverance, section 15
Struck with the contradictions which I encountered in endeavouring to disentangle the truth and falsehood of these opinions, I was led to make the following reflection: ‘The search after truth being the aim which I propose to myself, I ought in the first place to ascertain what are the bases of certitude.’ In the next place I recognised that certitude is the clear and complete knowledge of things, such knowledge as leaves no room for doubt nor possibility of error and conjecture, so that there remains no room in the mind for error to find an entrance. In such a case it is necessary that the mind, fortified against all possibility of going astray, should embrace such a strong conviction that, if, for example, anyone possessing the power of changing a stone into gold, or a stick into a serpent, should seek to shake the bases of this certitude, it would remain firm and immovable. Suppose, for instance, a man should come and say to me, who am firmly convinced that ten is more than three, ‘No; on the contrary, three is more than ten, and, to prove it, I change this rod into a serpent,’ and supposing that he actually did so, I should remain none the less convinced of the falsity of his assertion, and although his miracle might arouse my astonishment, it would not instil any doubt into my belief.
I then understood that all forms of knowledge which do not unite these conditions (imperviousness to doubt, etc.) do not deserve any confidence, because they are not beyond the reach of doubt, and what is not impregnable to doubt cannot constitute certitude.
This passage is important because it highlights a very specific understanding of knowledge which both drives al-Ghazālī’s intellectual inquiry and his reasons for skepticism. Al-Ghazālī suggests that only certain knowledge, where one comprehends the relevant object or proposition in such a way that there is no possibility of error or any room for (reasonable) doubt, is worthy of our reliance. As he understands it, this type of knowledge = infallible certainty. The only way to acquire knowledge that is worth relying on, then, is to find some means to it that precludes any possibility of error. This then grounds the basis of his skeptical worries because it turns out that it’s hard to find forms of knowledge that meet this high bar and are immune from doubt or error.
Second, in citing a tradition of the Prophet Muhammad, al-Ghazālī notes that human beings are born with a shared human nature (fiṭra) but that it is typically our cultural environment that shapes our beliefs, morals, and behaviors. There are many different religions and creeds, but where they conflict, only one can be right! Even so, the least we can do is strive to discover the truth despite our religious and cultural limitations. Al-Ghazālī thus instructs us toward the intellectual virtue of sincere truth-seeking, irrespective of our initial starting points. It is this intellectual virtue that is the springboard for al-Ghazālī’s skepticism.
One important debate in contemporary epistemology concerns whether knowledge should be understood in terms of infallibility or fallibility. Roughly, the former refers to the idea that, for a belief to count as knowledge, it must be grounded in such a way that it could not fail to be true. For example, knowing that 2 + 2 = 4 would count as an infallible belief, for as soon as we understand it, we immediately see that it must be true by definition. By contrast, fallibilism holds that a belief can still be knowledge even if it could have been mistaken — for example, believing it will rain tomorrow based on a weather forecast is fallible knowledge: it is reasonable and well-supported, but it could still turn out to be wrong. Most contemporary epistemologists are fallibilists, which means that al-Ghazālī’s view of knowledge might reasonably be challenged.
Having laid out precisely what he takes to be needed to acquire knowledge or comprehension of things, al-Ghazālī begins employing a method of doubt, stripping away all those things that do not meet his definition of knowledge in the search for some sure foundations upon which he can place his trust.
The Deliverance, section 16
I then examined what knowledge I possessed, and discovered that in none of it, with the exception of sense-perceptions and necessary principles, did I enjoy that degree of certitude which I have just described. I then sadly reflected as follows: ‘We cannot hope to find truth except in matters which carry their evidence in themselves—that is to say, in sense-perceptions and necessary principles; we must therefore establish these on a firm basis. Is my absolute confidence in sense-perceptions and on the infallibility of necessary principles analogous to the confidence which I formerly possessed in matters believed on the authority of others? Is it only analogous to the reliance most people place on their organs of vision, or is it rigorously true without admixture of illusion or doubt?’
In this passage, al-Ghazālī explains that, of all the beliefs he holds, there are two categories that may potentially meet his infallibility condition on knowledge: beliefs form on the basis of the senses, such as seeing that the sky is blue or hearing a bird sing, and necessary principles of reason, such as knowing that 2 + 2 = 4 or that a whole cannot be smaller than one of its parts. Might not these beliefs be the kind that al-Ghazālī can place full confidence in?
Second, in citing a tradition of the Prophet Muhammad, al-Ghazālī notes that human beings are born with a shared human nature (fiṭra) but that it is typically our cultural environment that shapes our beliefs, morals, and behaviors. There are many different religions and creeds, but where they conflict, only one can be right! Even so, the least we can do is strive to discover the truth despite our religious and cultural limitations. Al-Ghazālī thus instructs us toward the intellectual virtue of sincere truth-seeking, irrespective of our initial starting points. It is this intellectual virtue that is the springboard for al-Ghazālī’s skepticism.
Having cited beliefs formed on the basis of the senses and necessary principles of reason as potentially meeting the conditions for knowledge, al-Ghazālī then insists that he must nonetheless put them to the test in the same way in which he has done about the other types of beliefs he holds.
The Deliverance, sections 16-17
I then set myself earnestly to examine the notions we derive from the evidence of the senses and from sight in order to see if they could be called in question. The result of a careful examination was that my confidence in them was shaken. Our sight for instance, perhaps the best practised of all our senses, observes a shadow, and finding it apparently stationary pronounces it devoid of movement. Observation and experience, however, show subsequently that a shadow moves not suddenly, it is true, but gradually and imperceptibly, so that it is never really motionless.
Again, the eye sees a star and believes it as large as a piece of gold, but mathematical calculations prove, on the contrary, that it is larger than the earth. These notions, and all others which the senses declare true, are subsequently contradicted and convicted of falsity in an irrefragable manner by the verdict of reason.
Then I reflected in myself: ‘Since I cannot trust to the evidence of my senses, I must rely only on intellectual notions based on fundamental principles, such as the following axioms: Ten is more than three. Affirmation and negation cannot coexist together. A thing cannot both be created and also existent from eternity, living and annihilated simultaneously, at once necessary and impossible.’ To this the notions I derived from my senses made the following objections: ‘Who can guarantee you that you can trust to the evidence of reason more than to that of the senses? You believed in our testimony till it was contradicted by the verdict of reason, otherwise you would have continued to believe it to this day. Well, perhaps, there is above reason another judge who, if he appeared, would convict reason of falsehood, just as reason has confuted us. And if such a third arbiter is not yet apparent, it does not follow that he does not exist.’
In putting these sources of belief to the test, al-Ghazālī reflects on whether there could be room to doubt those beliefs produced by sense-perception and reason.
At the end of the last passage, we see that al-Ghazālī sets up an imaginary dialogue between sense-perception and reason, arguing that sense-perception is fallible and that reason shows that it is sometimes mistaken, like when it judges stars to be very small even though geometry proves otherwise. Significantly, however, al-Ghazālī concludes this dialogue by wondering whether, if reason shows sense-perception to be fallible, then there might be a higher cognitive ability or state above reason that would also show it to be mistaken too. If so, the apparent necessary principles of reason would also be in trouble.
In this following passage, al-Ghazālī continues his train of thought and specifically identifies the mystical state of ecstasy (ḥāl) as that potential cognitive ability—or ‘third aribter’—that stands above reason and its necessary principles. It is this notion that grounds his dream argument for global skepticism.
The Deliverance, section 18
To this argument I remained some time without reply; a reflection drawn from the phenomena of sleep deepened my doubt. ‘Do you not see,’ I reflected, ‘that while asleep you assume your dreams to be indisputably real? Once awake, you recognise them for what they are—baseless chimeras. Who can assure you, then, of the reliability of notions which, when awake, you derive from the senses and from reason? In relation to your present state they may be real; but it is possible also that you may enter upon another state of being which will bear the same relation to your present state as this does to your condition when asleep. In that new sphere you will recognise that the conclusions of reason are only chimeras.’”
This possible condition is, perhaps, that which the Sufis call ‘ecstasy’ (‘hāl’), that is to say, according to them, a state in which, absorbed in themselves and in the suspension of sense-perceptions, they have visions beyond the reach of intellect. Perhaps also Death is that state, according to that saying of the Prince of prophets: ‘Men are asleep; when they die, they wake.’ Our present life in relation to the future is perhaps only a dream, and man, once dead, will see things in direct opposition to those now before his eyes; he will then understand that word of the Koran, ‘To-day we have removed the veil from thine eyes and thy sight is keen.’
In this passage, al-Ghazālī lays out his central argument for global skepticism. The argument does not merely call into question the reality of the external world and our ability to know what exists outside our heads. Rather, it calls into question our knowledge of anything — including ourselves! Roughly, the argument seems to go something like this:
Premise 1: If it’s possible that there is a higher state than my current state of wakefulness, then I do not know what I think I know in my current state of wakefulness.
Premise 2: It is possible there is a higher state than my current state of wakefulness.
Conclusion: Therefore, I do not know what I think I know in my current state of wakefulness.
Al-Ghazālī can motivate the first premise by his remarks on knowledge. He holds that knowledge = infallible certainty, and so if there is a higher state beyond our current state of wakefulness that would show us that our current state is akin to a dream, then it looks like we could possibly be in error about what we think we know in our current state. The second premise is made plausible by al-Ghazālī through his thought experiment and dialogue, which invite us to imagine a scenario — such as being in a dream or higher state of consciousness — where our ordinary beliefs about the world turn out to be false. While unusual, this scenario is not logically impossible, which is why the premise is plausible. This argument is logically valid, which means that if the premises are true, then the conclusion is true. Al-Ghazali has given us some reasons to think that the premises are true. What do you think? Do we know that we are not dreaming? That we are not merely in some lower state of consciousness?
So, what is al-Ghazālī to do? As the passage below illustrates, global skepticism was not a welcome discovery for this seeker of truth and certainty. Yet, as we see, he does find some solution, or at the very least, a way out.
The Deliverance, sections 18-20
Such thoughts as these threatened to shake my reason, and I sought to find an escape from them. But how? In order to disentangle the knot of this difficulty, a proof was necessary. Now a proof must be based on primary assumptions, and it was precisely these of which I was in doubt. This unhappy state lasted about two months, during which I was, not, it is true, explicitly or by profession, but morally and essentially a thoroughgoing sceptic.
God at last deigned to heal me of this mental malady; my mind recovered sanity and equilibrium, the primary assumptions of reason recovered with me all their stringency and force. I owed my deliverance, not to a concatenation of proofs and arguments, but to the light which God caused to penetrate into my heart—the light which illuminates the threshold of all knowledge. To suppose that certitude can be only based upon formal arguments is to limit the boundless mercy of God. Someone asked the Prophet the explanation of this passage in the Divine Book: ‘God opens to Islam the heart of him whom He chooses to direct.’ ‘That is spoken,’ replied the Prophet, ‘of the light which God sheds in the heart.’ ‘And how can man recognise that light?’ he was asked. ‘By his detachment from this world of illusion and by a secret drawing towards the eternal world,’ the Prophet replied.
On another occasion he said: ‘God has created His creatures in darkness, and then has shed upon them His light.’ It is by the help of this light that the search for truth must be carried on. As by His mercy this light descends from time to time among men, we must ceaselessly be on the watch for it. This is also corroborated by another saying of the Apostle: ‘God sends upon you, at certain times, breathings of His grace; be prepared for them.’
My object in this account is to make others understand with what earnestness we should search for truth, since it leads to results we never dreamt of. Primary assumptions have not got to be sought for, since they are always present to our minds; if we engage in such a search, we only find them persistently elude our grasp. But those who push their investigation beyond ordinary limits are safe from the suspicion of negligence in pursuing what is within their reach.
In this passage, we find al-Ghazālī’s resolution to his spiritual crisis and his argument for global skepticism driving that crisis. Rather than resolving the skepticism on philosophical grounds, al-Ghazālī’s resolution takes the form of religious or mystical experience. In other words, he could not find a response to his problem of skepticism by reason or rational demonstration. Instead, his skepticism and doubt were eradicated through what he describes as a religious experience in which it seemed to him that God put a light into his heart that cured him of his spiritual and philosophical malaise.
Think about beliefs you feel sure about—like believing there’s a computer in front of you or that your favorite team will win. You might feel very convinced, but that psychological certainty doesn’t guarantee the belief is true. For example, you might feel sure you saw a ghost, but that feeling alone doesn’t make it real. By contrast, epistemic certainty is when a belief is guaranteed to be true, such as knowing that 2 + 2 = 4 or that all triangles have three sides. As we’ve seen, Al-Ghazālī is concerned with this second kind of certainty: he wants to know which beliefs, if any, we have infallible evidence for and which can be reasonably doubted, regardless of how strongly we feel about them.
Can you think of a belief you are psychologically certain about that might still be wrong? Are there any beliefs you feel certain about that might also be epistemically certain — how do you know? Why might it be important to distinguish between what we feel certain about and what is guaranteed to be true?
In al-Ghazālī’s Deliverance, we saw how he struggled with skepticism and sought to resolve what turned out to be both a philosophical and spiritual concern for him. In his quest for knowledge, al-Ghazālī’ engaged in an intellectual inquiry in pursuit of certainty. By setting up a dialogue between his two main candidates for certainty — sense-perceptual beliefs and necessary principles of reason — he imagined a higher cognitive ability; a form of mystical ecstasy or apprehension (ḥāl), that may well expose the truths of reason as being illusory, much like the way our state of wakefulness reveals our dreams to be illusions. In the end, only the God-given light that penetrated al-Ghazālī’s heart is sufficient to rid him of his skepticism and spiritual crisis.
Several scholars working in the history of philosophy have noted the remarkable similarities between al-Ghazālī’s argument for skepticism, and his general method of doubt, with that of Rene Descartes. Despite the similarities, though, there are important differences between the two thinkers in their journeys through skepticism and their eventual solutions. Descartes’ case for skepticism can be found here.
First, Descartes’ central argument for skepticism, known as the evil demon argument, is an argument for external-world skepticism as opposed to global skepticism. This is evident from his famous line: cogito ergo sum (“I think, therefore I am”), where he suggests that it’s impossible to doubt one’s own existence. Al-Ghazālī’s argument, on other hand, even calls into question knowledge of one’s own existence. For it may be that as we ascend to higher and higher states of consciousness, as his dream argument alludes to, we begin to transcend or annihilate any notion of selfhood and reach pure cosmic consciousness.
Second, both thinkers make use of an analogy to dreams but in different ways. While Descartes uses the notion of dreams to question sense-perception, al-Ghazālī uses it to question reason itself.
And third, although both invoke God in their response to skepticism, their approach is significantly different. For Descartes, God — a perfectly good being — is proved through the ontological argument, while for al-Ghazālī’, God is contacted through a spiritual union that cleanses his heart of doubt. So, whereas the former sought to resolve doubt from within the domain of philosophy where that very doubt was initiated, the latter stepped outside that domain altogether.
If you’d like to learn more about al-Ghazali’s spiritual and philosophical journey, pick up the story in the remaining segments of his Deliverance, where he begins an inquest into the different intellectual traditions of his day. For an overview of how contemporary philosophers view both the issues of skepticism and certainty, see the articles “Contemporary Skepticism” and “Certainty” in the Internet Encyclopedia of Philosophy.
Excerpts from The Deliverance from Error used in this essay come from the version available in the public domain at Project Gutenberg. All images were created using Midjourney.
Turner, Jamie. 2026. “Is It All But A Dream? Al-Ghazālī’s The Deliverance from Error.” The Philosophy Teaching Library. Edited by Robert Weston Siscoe, <https://thephilosophylibrary.org/article/all-but-a-dream>.
Underlier (Greek hypokeimenon) – in Aristotle’s account of change, what remains constant throughout the change and by which form is acquired and privation is lost. For instance, if Socrates becomes musical from being unmusical, Socrates is the underlier. (N.B. This same Greek term is also, especially in logical and metaphysical contexts, often translated as “subject”.)
Relations of Ideas – these are claims we come to believe without any sensory experience required. For instance, we can come to realize that a circle has a perfect center point without discovering any perfect circles in the world. All we need to do is think clearly about what it means to be a circle!
Here, Kant refers to Frederick the Great (Friedrich II, 1712-1786), who was King of Prussia. A supporter of the Enlightenment, Frederick endorsed social and political change by abolishing torture and expanding the educational sector. He suspended censorship for newspapers with the exception of political content. Supporting freedom of religion in general, he nevertheless favored protestants for political higher office and did not grant Jews civil rights.
Monarchy – A monarchy is a state where political deliberation is performed by one person (generally a king or queen).
Phalaris (c. 570-549 BCE) was, by most accounts, the very opposite of Cyrus, and he was used as an example of tyrannical cruelty in antiquity. He was tyrant of Acragas (now Agrigento) in Sicily. Diodorus Siculus records an infamous account of Phalaris’s torturing his enemies in a bronze bull placed over a roaring fire.
Cyrus the Great (d. 530 BCE) was the first emperor of the Persian Empire and a commonly used exemplar of the “enlightened monarch” in antiquity. He was renowned for his tolerance and care for his subjects. Xenophon, a student of Socrates, wrote a partly fictionalized biography of Cyrus called The Education of Cyrus (Cyropaedia). Peter Drucker, an influential 20th-century management theorist, called the Cyropaedia the best book on leadership.
Republic (res publica) – Cicero’s short definition of res publica is res populi (the ‘people’s thing’). Later in the Republic, Cicero famously defines a republic (1.39) as an assemblage of people associated with each other by consensus on justice (ius) and mutual benefit (utilitas).
Scipio Aemilianus Africanus was a hero among many Romans, but his reputation today is far less straightforward. Scipio Aemilianus led a Roman military campaign resulting in the utter destruction of the city of Carthage in 146 BCE. The Carthaginians were a prosperous Phoenician people in North Africa and rivals to Roman power. It has been argued that this act of ‘national extermination’ meets the modern definition of genocide. How should this knowledge impact how we view Scipio’s political philosophy expressed here?
This famous phrase, known by the abbreviation SPQR (senatus populusque Romanus), served as something like the official title of the Roman state (compare ‘USA’, ‘USSR’, ‘UK’), and encapsulated the ideal of a res publica (common property in public hands shared between the people and a council of elders).
Contemplation: The activity of human beings’ rationality. Contemplation is more than just thinking; it’s thinking excellently about ultimate truths. Contemplation is the ultimate activity associated with human flourishing.
Eudaimonia: Often translated as ‘happiness’ (in this text) or ‘flourishing’, eudaimonia is the activity of living the best possible life for a human being. Eudaimonia is more than just feeling happy or contented – it’s the idea that there is a best way to live for human beings.
Virtue: Virtues are cultivated tendencies to perform our function excellently, which allow us to reliably do the right thing, to the right extent, for the right reasons, given the demands of a specific circumstance. There are three components of virtues: virtues involve (a) skillful activity – they’re excellences after all!, (b) proper motivation, and (c) appropriate judgment – they often lead to judgments about what is the right thing to do, which requires careful attention to the circumstances.
Pleasure: The enjoyable feeling that accompanies some activities. Some philosophers (but not Aristotle!) think that pleasure is the only thing that is good in itself
Endoxic Method: An argumentative structure that begins by laying out the endoxa, or the beliefs of the many or the wise, then raises apparent problems for those views and develops a resolution to those problems.
The Problem of Induction: A problem for reasoning about the future based on past experiences. How can we be justified in believing that patterns of events in the past will continue into the future?
A Priori: Hume is using the term ‘a priori’ to denote the kind of reasoning that allows one to gain knowledge as relations of ideas—in other words, reasoning from one necessary, definitional truth to another.
Justification: the concept of justifying one’s thinking, or one’s beliefs, is important in epistemology. Roughly, one’s thinking or belief is justified when there is good reason for it, or when it is well supported or well evidenced. All of these are ways of referring to some connection between what we think or believe and what is, or to some way of at least making ourselves think that we are closer to the truth.
Inference: The psychological process of moving from one thought to another, such as moving from the thought “it’s raining, and I don’t want to get wet” to “I should get my umbrella”, or from “I am tired, and it’s getting late” to “I should get some sleep”. Nowadays, philosophers tend to use the term ‘inference’ to mean the same as ‘reasoning’, and tend instead to use the term ‘association’ to refer to movements between thoughts that are not based on any logic or evidence.
Matters of Fact: Knowledge that is gained by experience, such as by observing or experimenting with objects in the world. For example, knowing whether all swans in the world are white requires somebody to examine the many swans in the world and make sure they do not happen to discover a black one (and in fact, there are black swans!).
Relations of Ideas: Knowledge that is gained just by sufficiently clear thinking, without having to observe or experiment with objects in the world. For example, knowing that a triangle has three sides is something you can know just because of what it means to be a triangle, hence without having to carefully examine triangular objects that you find throughout the world.
Reasoning: Developing arguments to try and support the truth of one’s beliefs.
Causation: A relation between events, where one event (cause) is responsible for another (effect). Eating too much chocolate can cause the effect of having an upset stomach, and not getting enough sleep can cause someone to be grumpy.
Epistemological Theories: Theories about the nature and possibility of knowledge – whether, when, how, and to what extent we can know about reality, such as the physical world, or our own consciousness. For example, one epistemological theory says that we can gain understanding of our own consciousness by studying the brain, whereas other theories say that we can only gain knowledge of consciousness by reflecting on our own inner experiences.
Aristotle means “happy” in the sense of a person who has developed a complete character, lived a full life, and become a true example of human goodness.
Happy Person – Someone who has developed her entire self well and lived a complete and flourishing life. She is a real and positive example of how we should live.
This is where Aristotle defines virtuous friends. These are friends who you actually answer the phone for. These are the friends who you ask for advice on work, love, and life. They are the friends that celebrate you for being you, but they also tell you when you’re messing things up. Not only do they love you, but you love them and try to be the same kind of friend to them too.
This is where Aristotle defines pleasurable friends. These are your TikTok, Snap Chat, or Instagram friends, the ones you post to social media when you’re having a good time.
This is Aristotle’s explicit definition of useful friends. These are your LinkedIn friends, those who you like networking with at events or enjoy working with on projects.
Virtuous Friendship – A friendship where people set as their goal for their friendship becoming good people together and living happy lives just because they value the good of their friends as persons. These are also known as “perfect” or “true” friendships. They are usually between people who are equally good. And they might be limited to people of equal social status, wealth, and power. Aristotle doesn’t think that any happy person will lack virtuous friends. But he thinks it’s likely that we’ll only have a few of this sort.
Pleasurable Friendship – A friendship where people set as their goal for their friendship some pleasant goal, such as friendship between people who go out on the town together. These friendships are plentiful and easy to form and dissolve.
Useful Friendship – A friendship where two people set as their goal for their friendship some useful or utilitarian purpose, such as friendship between work colleagues. These friendships are plentiful and easy to form and dissolve.
Aristotle uses “friend” broadly for any relationship between people who like each other, wish good things for each other, and get something out of spending time together.
Friendship – A relationship between two people who like each other, generally wish each other well, and have a goal for their interactions.
Happiness – The final end and highest good of human life. The perfect good that objectively fulfills human nature and subjectively satisfies desire.
Happiness Criteria – The conditions that the true object of happiness must satisfy. They are: finality, intrinsic value, purity, internality, authenticity, stability, self-sufficiency, completeness.
Object of Happiness – The thing in which happiness essentially consists, the attainment of which will make us truly happy.
Highest Good – The greatest good for a human being.
Final End – The ultimate goal of human life. All of our other goals are chosen for the sake of this final end.
Constituent Principles – Parts of a material object that cause the object to be the sort of thing that it is, but that cannot be removed from that object (in the way that some properties can be gained or lost). For Aquinas, this would include things such as form (the structure of a material object) and matter (that which is structured). For example, Dylan’s form is his soul, and his matter is his body. His soul and body are distinct, but Dylan could not exist if he were not composed of both.
Accident/accidental property – A property that something can possess or not possess while still remaining the thing that it is. For example, Dylan could grow taller, or he could stop being musical, without becoming a different person. By contrast, rationality is an essential property of Dylan, since being rational is part of the “what it is to be” of a human being.
Subject/Suppositum – Something or someone that can bear properties but is not itself a property that something else can bear. Dylan can have properties, like being short or being musical, but no one can have Dylan as a property.
Property – A feature that an object has. For example, a ball could be orange, which means that the ball has the property of orangeness. In many cases a property can be gained or lost. The ball could be painted green, in which case it would gain the property of greenness and lose the property of orangeness.
Actuality – The being, or act of being, of a thing. For example, hot water is actually hot (the water is hot), even though it is potentially cold. Likewise, a boy is actually a human being (he is a human being), even though he is also potentially a full-grown man (and he will still be an actual human being when he becomes a full-grown man).
Potentiality – Ways a given thing can become different from the way it is now. For example, cold water is potentially hot, since it can be heated up, and an acorn is potentially an Oak tree since it can grow to full size under the right conditions.
Essence – The “what it is to be” of a thing. For example, the essence of a human being is to be a rational animal, and the essence of a cheetah is to be the fastest land animal.
Principle of Specialization – The idea that work is more efficient and more effective if each worker specializes in exactly one task.
Extrinsic Value – Value a thing has that is dependent on something else. Extrinsically valuable things are worth pursuing because they get you something else that is valuable. Money, for instance, is only useful because it can be exchanged for other things.
Intrinsic Value – Value a thing has independently or inherently. Intrinsically valuable things are worth pursuing for their own sake.
Adeimantus and Glaucon were Plato’s older brothers (along with an older sister, Potone). They were both honored for military valor at a battle with Megara. We know little about their lives otherwise. Potone had a son, Speusippus, who inherited leadership of the Academy upon Plato’s death.
Thrasymachus was a real person, who lived about 459-400 BCE moved to Athens from Chalcedon to become a sophist (a professional teacher and public speaker). Only a few fragments of his work survives
Prudence – Prudence is virtue wherein a person is able to choose, in any given situation, the course of action that will lead to greater happiness. For example, a prudential person knows when it is appropriate to continue a difficult conversation and when it is best to wait for a more appropriate time.
Pleasure – Epicurus would have us think about pleasure as coming in two forms: moving and static. Moving pleasures are the type that we experience in the process of satisfying a desire (this coffee tastes amazing!). Static pleasure is the feeling of being satisfied — no longer experiencing need or want (I am feeling so peaceful sitting in the park). Epicurus thinks these static pleasures are the best sort.
Epicurus believed that reality is composed of matter. This sets him apart from other philosophers of the time who, often influenced by Plato, believed that reality is composed of both the material and immaterial (like the soul, or the Platonic forms).
Happiness – Epicurus uses the Greek word “eudaimonia,” which is typically translated into English as “happiness.” Whereas today happiness is most often used to describe a momentary feeling (this new notebook makes me happy!) Epicurus means something more like a consistent state of well-being and contentment.
Unconditioned: an ultimate explanation of reality. For example, if I explain why it is raining today by appealing to some atmospheric conditions, I can always ask for the cause of those conditions, and so on. Only a cause that is not caused by anything else (something unconditioned) would give us an ultimate explanation.
Transcendental Idealism: Kant’s mature philosophical position. It holds that appearances are not things in themselves, but representations of our mind. It is opposed to transcendental realism, which identifies appearances with things in themselves.
Appearances (vs. things in themselves): things as they are experienced by us (also known as phenomena). They should be distinguished from things as they are independently of our experience (things in themselves or noumena).
Metaphysics: the study of what there is. Traditionally, metaphysics is divided into general metaphysics and special metaphysics. The former investigates the general features of reality and asks questions such as ‘What is possible?’. The latter studies particular kinds of being and asks questions such as ‘Does God exist?’ or ‘Is the soul immortal?’.
Reason: the faculty that knows a priori. Kant uses this term in a general sense (the knowing faculty as such) and in a specific sense (the faculty that demands ultimate explanations).
A priori: term denoting propositions that can be known independently from experience. For example, propositions such as ‘All bachelors are unmarried’ or ‘The whole is greater than its parts’ can be known without recourse to any experience.
Make sure not to think that ‘unjustified’ means ‘false.’ Even if they are true, the point is just that this would not be something that had been shown.
‘Absolute’ might be a confusing word, here. Socrates means that the geometers are not reasoning about their drawing of the square, for example, but of the square itself. They do not conclude that, for the square they drew, the area is equal to the square of a side – they conclude that this is true for squares as an intelligible object, or, as Plato would say, the Form of the square.
By ‘science’, Plato means to be talking about all rational disciplines, including mathematics.
The form of the beautiful has to be perfectly beautiful because all instances of beautiful things are explained by it, so it has to be responsible for the highest possible degrees of beauty possessed by anything. Moreover, it has no trace of ugliness in it.
The form of the beautiful has to be immaterial because all the many beautiful things do not share any material – that is, they are all made of different stuff.
Form (εἶδος / ἰδέα) – Intelligible, immaterial, perfect entities that explain the unity among the many things which share the feature named by the entity (e.g., Beauty, Squareness, Oddness). For example, think of a square. There might be many different squares, but they all share features like having four sides of equal length. So, the Form of Squareness would include all of those features that make something a square.
Guardian – This is the name Plato gives to the ruling class in his ideal city. Think of them as philosopher kings – they have complete control over the organization of the state. The Republic is partially about why Plato thinks they would be needed for an ideal system of government and what they would need to learn to do the job well.
Plato has previously argued that we are made up of different parts. The first part is the appetitive which is responsible for our desires for food, sex, and other bodily needs. Then there is the spirited part, which longs for fame and honor. Finally, he identifies the rational part, which discerns what is good and bad for us through reason. The parts can all come into conflict with one another, and managing their relations is what Plato thinks justice is all about.
Soul (ψῡχή) – What Greeks meant by this word is controversial. For now, think of it as the thing that makes you different from a rock or other objects, the thinking and experiencing part of you as well as the part of you that acts and makes decision. You might use the word ‘mind’ or ‘self’ to talk about this.
Virtue – Virtues are the character traits that make a person good. For example, most people consider courage and generosity to be virtues. English-speakers usually reserve the word ‘virtue’ for human beings, but in ancient Greek the word can be more comfortably applied to other beings as well.
Was it his burly physique, his wide breadth of wisdom, or his remarkable forehead which earned him this nickname?
Aporia – A Greek term for “being at a loss” or “clueless.” Socrates often questions people until they have no idea how to define something that they thought they understood.
You might be confused by the word ‘attention’ below. In Greek the word is therapeia, from which we get the English word ‘therapy.’ It primarily means the same as ‘service’ as in ‘to serve,’ but shades into ‘worship,’ ‘take care of,’ and ‘attend to.’
Meletus – A poet and citizen of Athens and one of Socrates’ accusers. Amongst other things, Meletus accused Socrates of impiety and corrupting the youth.
Divine Voluntarism – The idea that God is free to determine even the most basic truths. If divine voluntarism is true, then God could have made it so that 2+2=5 or so that cruelty and blasphemy are holy and good.
Euthyphro Dilemma – The question, “Is a thing holy because the gods love it, or do the gods love it because it is holy?” The general idea of a forced choice (or “dilemma”) about the true order of explanation occurs often in philosophy and gets referred to by this term.
Essence – What a thing fundamentally is. A square might be red or blue without changing the fact that it’s a square, but a square must have four sides, so having four sides is part of a square’s essence.
Definition – The perfect description of a thing. A definition should pick out all and only examples of a thing. For example, ‘bachelor’ might be defined as ‘unmarried man,’ because all unmarried men are bachelors, and only unmarried men are bachelors.
In Disney’s retelling of the Hunchback of Notre Dame, the clergyman Claude Frollo orders the death of many Roma on religious grounds. It is clear, however, that he is really motivated by spite and his unrequited lust for the Romani woman Esmerelda.
Spanish conquistadors were shocked by the scope of ritual human sacrifice among the Aztecs, as hundreds or even thousands of people were sacrificed each year. The Aztecs thought that the sacrifices could repay the sacrifices the gods had made in creating the sun and earth.
Zeus – The god of sky and thunder in ancient Greek mythology, Zeus was depicted as chief among the gods and called the father of the gods and men.
Forms – The perfect, divine, and intelligible entities that exist independently of the physical world. They are comprehensible only through reason, not through our senses, and their existence explains the properties of objects in the physical world.
Recollection – The soul existed prior to birth; during this time it learned everything, and hence all learning is only recalling what we already know.
Immortality of the Soul – Unlike the body, the soul is not subject to physical death, because it is immortal and indestructible.
Philosophy – The practice of preparing the soul for death by training it to think and exist independently of the body
Death – Plato understands this as the soul’s separation from the body
Human Identity Across Time – Locke’s notion that any human stays the same across time if, and only if, it maintains the same (distinctively human) organizing structure of parts.
Substance Identity Across Time – Something is the same substance across a segment of time if, and only if, it continuously exists across the relevant segment of time without gaining or losing any of its parts.
Immaterial Soul – A personal thinking substance without any physical constitution.
Personal Identity Across Time – Whatever makes someone the numerically same person (i.e., that very person) at different times; according to Locke, it is a relation of first-person consciousness via memory.
Person – Locke’s forensic definition of person (pertaining to courts of law regarding the justice of praise, blame, reward, or punishment): a thinking, intelligent being, that has reason and reflection, and can consider itself as itself, the same thinking thing in different times and places.
The Prophet Muhammad is a central figure in Islam. He is viewed as the last of a long line of prophets, which includes Moses and Jesus. He is responsible for writing the Quran, which was dedicated to him by the angel Gabriel. His life and sayings are recounted in the Hadith; he is viewed as an exemplary role model of Islamic life and faith.
Exhortation — The method of understanding and interpreting Truth available to the common people. The majority of people take scripture literally and understand truth and right action based upon this understanding. They are persuaded by the vivid imagery of the Quran and the rhetorical exhortations of religious leaders. Averroes takes this to be lowest form of understanding
Dogmatic Discourse — The method of understanding displayed by those who, through natural ability and habit, are able to have a deeper understanding of the Quran, and of the truths it illuminates. These people know that not all of the scriptures are to be taken literally, and that greater underlying Truths are revealed by interpreting some elements allegorically. Still, they err on the side of dogmatism and literal interpretation whenever uncertainty arises. Averroes associates this way of thinking with Muslim theologians and views this to be the middle level of understanding.
Philosophical Inference – The type of understanding associated with philosophical demonstration or argument. This is the highest level of understanding, accomplished by a select few, who have a natural capacity for philosophy and proper philosophical training.
Law — The Quran (the central religious text of Islam) and, to a lesser extent, the Hadith (reports of what the prophet Muhammad said and did). Averroes is concerned with explaining how philosophy relates to what Muslims take to be the unerring Truth regarding God and the nature of existence, as they are expressed in Scripture.
Occasionalism — a theory claiming that God is the only true cause of changes in the world. For example, when you high-five me, you’re not really the cause of the stinging sensation I experience. God is the cause. Your high five is just the occasion on which God causes it.
Interactionism — a theory claiming that things in the world can truly cause changes in each other. For example, when you high-five me, you truly cause me to experience a stinging sensation in my hand.
Substance Dualism — a theory claiming that the mind (or soul) and body are two distinct and very different things.
Body — what it sounds like! The body is the physical part or aspect of a thing and has characteristics like shape, size, etc.
Soul — that part or aspect of a thing involving mental aspects of their existence, e.g., thoughts, feelings, decisions, etc. The “soul”, in this sense, is more or less just the mind.
Causal Interaction — When one thing acts (i.e., itself does something) and in so acting makes another thing change. For example, when you high-five me, you cause me to experience a stinging sensation in my hand.
God as God – The phrase “God as God” is basically a synonym for “God the subject.” In other words, it refers to God precisely in God’s status as an incomprehensible divine Other.
Incarnation – The Christian doctrine of the incarnation is the notion that the word of God became fully human in the person of Jesus of Nazareth. It is closely associated with the doctrine of the trinity, which asserts that God the Father, God the Son (Jesus as the word made flesh), and God the Holy Spirit are one God.
Religious Fanaticism – In Feuerbach’s use of the term, a religious fanatic is someone who is unwaveringly faithful to God as an utterly mysterious superhuman being. They subordinate other things—especially the love of other humans—to submission before this divine other.
God the Subject – When Feuerbach refers to God as a subject, he is referring to the commonplace religious belief that God is a being who has various attributes, like a loving nature.
Faith Separates Man From God – Faith separates God from man in this sense: it treats God as a mysterious other, a being radically distinct from us.
Faith – Belief in and fidelity to a transcendent divine subject like God.
Orthodoxy – Orthodoxy refers to “right belief,” and it is concern with identifying heresies and ensuring that people believe and practice correctly.
Indirect Form of Self-Knowledge – Feuerbach’s view is that religious belief is a naive way of relating to our human nature and its perfections. It is naive or childlike because it treats these as external realities that belong to God. He believes a mature and contemplative person realizes these don’t belong to God, but rather to our species, abstractly conceived.
Above the Individual Man – The human perfections are “above the individual” insofar as no particular individual ever perfectly realizes them. They are abstractions.
Divine Trinity – Feuerbach is having fun here. He is using the theological phrasing of the Trinity to talk about human perfections. In calling reason, love, and freedom of the will “divine,” he means they are absolutely good; they are activities whose goodness is intrinsic to their practice or exercise. This isn’t a novel philosophical view. For example, Immanuel Kant argued that autonomy or a good will is the only thing which is unconditionally good.
Perfections – The end to which a faculty or power is ordered. For example, omniscience would be the perfection of the intellect. Traditionally, God is said to possess all perfections.
Love – When Feuerbach writes about love, he is referring to unconditional concern for others and the desire for fellowship with them. He is here asserting that love, understood in this sense, is the perfect activity of the affective faculty. In other words, our feelings and passions are fully actualized and engaged in an intrinsically valuable activity when we genuinely love others.
Infinite – The infinite is whatever can be understood as unbounded or unlimited. Human nature in the abstract is unbounded and unlimited. It is only bounded or limited in its concrete form as it is realized by particular material individuals.
Higher Consciousness – The sort of consciousness that mature human beings possess, but which other animals do not. It is “higher” than animal consciousness because it involves thinking abstractly about the form or essence of things.
Science – Feuerbach uses the term science in its classical sense, meaning systematically organized knowledge. Any body of knowledge founded on an understanding of first principles and the essences of things is a science in this sense.
Popular Sovereignty – The view that a government’s authority to rule comes from the people, making a ruler subject to the will of their citizens.
The Divine Right of Kings – The theory that kings are chosen by God and thus that political revolt is a rebellion against the will of God.
Synthesis – The prefix ‘syn-’ means “together,” so a synthesis “brings together” or combines elements of both a thesis and its antithesis.
Antithesis– An antithesis is the contradiction of a thesis. For example, internationalism could be understood as the antithesis of nationalism.
Thesis – In Hegelian terms, a thesis can be understood as a position or theory. Examples include any of the “-isms” that we discuss in science, history, and philosophy, such as Darwinism, capitalism, nationalism, etc.
Progressor’s Temptation – a unique temptation for those making progress in which pride impedes their further progress and leads to backsliding.
Progressors – those who are not yet expert Stoic practitioners, but who are also aware of the fact that they must change their lives in that direction. They are working on making progress.
Intellectualism – the philosophical view that our motivations and emotions are all judgments. The reason why you do something, your motivation, is because you believe it’s the right thing to do. The reason why you feel good or bad about something, an emotion, is because you believe that something good or bad happened to you.
Duties – acts of service, obedience, and respect that we owe to each other. The duties we owe to each other depend on what kind of relationship we have.
Askeses – exercises of Stoic thought and practice that make the lessons and habits of Stoic philosophy second-nature for Stoic practitioners.
Externals – things that are not under our control but that are all-too-easily confused with things that should be important to us, like wealth, status, and pleasure. Too many people believe externals like these are necessary for the good life, and the Stoic path is to focus not on these things but rather what is up to us.
The Fundamental Division – the division between things that are under our direct control and those that are not. The important lesson is to care only about the things we can control.
The Greatest Happiness Principle – A principle which says that actions are right insofar as they promote happiness and wrong insofar as they promote unhappiness
Higher and Lower Pleasures – Types of pleasures that differ in terms of their quality. Things like food and drugs create lower pleasures. Things like intellectual pursuits and doing the right thing create higher forms of pleasure.
The Doctrine of Swine – An objection that utilitarianism entails that if people would be happy rolling in mud, that’s what would be morally best for them to do, so we should reject the theory.
Utilitarianism – A normative theory of which actions are right or wrong. Utilitarianism says the right action is that which maximises utility.
Jeremy Bentham – Considered by some as the father of utilitarianism, Bentham was a moral philosopher and one of John Stuart Mill’s teachers
Epicurus – an ancient Greek philosopher and one of the first to advocate that the ultimate good is experiencing pleasure and avoiding pain.
Utility – The thing that is ultimately valuable in itself. For Mill, this is happiness, which he then understands as pleasure and the absence of pain.
Contract Theory – a modern political theory identifying consent as the sole justification for government. Contract theory is associated with Thomas Hobbes (1588-1679), John Locke (1632-1704), Jean Jacques Rousseau (1712-1778), and more recently, John Rawls (1921-2002)
Prejudice – a foundational, strongly held, unreasoned (but not necessarily irrational) moral opinion or belief. We might believe, for example, that parents have special obligations towards their own children.
A Priori – a philosophical term of art meaning (in Latin) “prior to experience,” which refers to knowledge that is innate or arrived at purely through reasoning, like the truths of mathematics.
Rights – moral claims invoking immunity from (or entitlement to) some specific treatment (or good) from others. Commonly recognized rights include the right to free speech or the right to healthcare.
Reform – a change in the social order that originates from the existing character of society. An example would be market-based healthcare reform in a capitalist society.
Conservatism – a modern political ideology that aims to preserve and promote the existing (or traditional) institutions of society. These institutions typically include the rule of law, property, the family, and religion.
Contingent Being – A being that can fail to exist. Its existence is not guaranteed. This being might come to exist or it might not.
Necessary Being – A being that can’t fail to exist. Its non-existence is impossible. This also means that such a being has always existed.
Want to read more about why the infinite regress option doesn’t work in the Second Way? Check out Sean Floyd’s entry in the Internet Encyclopedia of Philosophy.
Efficient Cause – An efficient cause is something that directly makes another thing exist or move. An example of this is when I kick a ball down a hill. I am the efficient cause of the ball rolling down the hill because I make it move down the hill.
Infinite Regress: Begin with some fact. We begin to explain that fact by appealing to another fact, where these facts are related by either causality or dependence. To create the regress, you keep appealing to more and more facts about causality and dependence without end.
Actuality – An ability or action something is currently exercising. Imagine that I am sitting comfortably at my desk, and then I stand up to take a break from reading. In this case, I am now actually standing.
Potentiality – What something has the capacity to do, but isn’t currently doing. Imagine I am sitting comfortably at my desk. Even though I’m not currently standing, I have the capacity to be standing. So, even while I’m not standing, I have the potential to stand.
Theists and Non-Theists – A theist is someone who believes that God exists, while a non-theist does not. Non-theists include atheists, who believe that God does not exist, and agnostics, who are uncertain about whether God exists.
Glaucon – one of Plato’s brothers and one of Socrates’ main interlocutors in the Republic dialogue. In that dialogue, he challenges Socrates to provide a compelling justification for why one should be a just person beyond merely following conventions or avoiding punishment. This sets up Socrates’ defense of justice as intrinsically worthwhile. Throughout the Republic, Glaucon prods Socrates to fully explain his theories of the ideal society, philosopher-kings, and the Form of the Good.
Aristotle – a Greek philosopher (384-322 BC) who studied under Plato and went on to be one of the most influential philosophers to ever live. Simply called “The Philosopher” by Thomas Aquinas and others in the medieval period, Aristotle’s views would eventually be synthesized with Christian theology, laying the intellectual foundation for later scholarly developments in Western Europe.
Understanding – Socrates describes education as turning one’s “understanding” in the right direction. The word “understanding” here translates the ancient Greek term “to phronēsai,” which means “understanding,” “being conscious,” or “having insight.” People who are wicked focus their “understanding” on how best to accomplish their selfish and narrow desires. Those who are wise, in contrast, have learned to focus their “understanding” on what is truly good and beneficial.
The Form of the Good – Socrates characterizes the ultimate goal of education as coming to know “the Form of the Good.” The Form of the Good is his technical term for the meaning of goodness: what it is to be good. Socrates is clear that this “knowledge of the Good” is not simply theoretical knowledge, but also knowledge in the sense of “knowing how”: knowing how to achieve what’s good, to do what’s good, to accomplish what’s good. Mere “book knowledge” or simply being smart is not enough.
The Intelligible – Socrates uses “the intelligible” to name the aspects of the world that we can only grasp through thinking or insight. With my eyes I can see the tree outside my window, but what it means to be a tree is something I can only comprehend in thought. Likewise, I can see the people around me, but human nature, human dignity, and what it means to be human is something I can only grasp conceptually. “The intelligible” is the world insofar as it “makes sense” and can be comprehended.
The Visible – By “the visible,” Socrates means those aspects of the world we can perceive with our five senses and our imagination—those aspects of the world we can see, hear, taste, smell, touch, and imagine. For example, with my eyes I can see the sky, trees, people around me, and so on as visible things. “The visible” is the world insofar as it can be perceived and imagined.
Education – Socrates says that the allegorical story he tells represents the effect of education on human nature. “Education” here is a translation of the ancient Greek word “paideia,” which means “education” in the widest sense of the term. “Paideia” doesn’t mean “education” in the sense of going to school or getting good grades. Instead, it refers to the process of becoming a wise, intelligent, good, and well-rounded human being.
Allegory – An allegory is a symbolic narrative where characters, events, and/or settings represent abstract ideas or convey deeper meanings beyond the literal story. Socrates tells such a symbolic narrative in the passages below. The characters, events, and setting of his narrative symbolize the effect of what he calls “education.”
Self-knowledge – Knowledge of the contents of one’s own mind, such as one’s own beliefs and desires. Self-knowledge can be gained through introspection, that is, by reflecting on what one thinks and experiences. Some philosophers believe that self-knowledge has special properties that our knowledge of the external world lacks, such as being clearer, more reliable, or more valuable.
Dualism – The view that the mind is entirely distinct from the body. This view is usually contrasted with different kinds of monism, which hold that the mind is ultimately just a part of the body (materialism) or that the body is ultimately just a part of the mind (idealism). Dualists hold that the mind and the body are fundamentally different aspects of reality, and both categories are needed to properly describe the universe, especially the human person.
The Self – What the ‘I’ in ‘I am, I exist’ refers to; the part of you that really makes you you. Many philosophers have provided rich accounts of what the self ultimately is, including the soul, the mind, one special feature of the mind (such as consciousness), a mixture of all these elements, or perhaps a mere illusion.
The ‘Cogito’ – Descartes’ famous claim ‘I think, therefore I am’ is often referred to as the cogito. The name comes from the Latin rendering of this phrase, which is ‘cogito, ergo sum.’ Descartes held that one can always believe this proposition with certainty. We cannot doubt our own existence, so the cogito survives his exercise of intense doubt. The cogito appears several times in Descartes’ writings, and he often phrased it slightly differently each time. It appears in the Second Meditation as ‘I am, I exist.’
Certainty – When one believes something with certainty, one is maximally confident that it is true. A certainty is something that is beyond dispute or immune to doubt. Although this captures the basic idea, like many epistemological notions, clarifying precisely what the notion of certainty amounts to is an ongoing area of philosophical research.
Vice – A bad habit that we learn over time through instruction or instinct and that we develop through repetition. What makes the habit bad is that, once we have that habit, our tendency is to do the incorrect thing in certain types of situations. We may choose to do something entirely uncalled for in that situation, or we may act at the wrong time, in the wrong way, to the wrong degree, or with the wrong attitudes, or for the wrong reasons.
Relative Mean – The “Goldilocks amount” of some type of action or emotion. When you act in this way, according to Aristotle, you act exactly as is required under the current circumstances. This means that you do what is called for by the situation at hand, rather than doing something too extreme or not doing something extreme enough. You do something in the moderate amount (the mean amount) relative to the specific situation you are in when you need to act.
Excellence/Virtue – A good habit that we learn over time through instruction and repetition. What makes the habit good is that, once we have that habit, we have a strong tendency to do the right thing at the right time, in the right way, to the right degree, with the right attitudes, whenever we are confronted with a situation that we know calls us to exercise that habit.
Doxastic Voluntarism – the view that we have at least some control over what we believe.
Evidence – information that increases the probability that a claim is true.
Sufficient – enough of something for a particular purpose. Whether something is sufficient is context-dependent.
Solon – In the Histories of Herodotus, Solon visits Croesus, the king of Lydia. Even though Croesus shows Solon all of his wealth, Solon refuses to call him the happiest man who ever lived because he does not know how Croesus will die
Priam – According to Greek mythology, Priam was the final king of Troy during the Trojan War. Despite his wealth and political power, he was killed by Achilles’ son Neopotolemus during the Sack of Troy
Virtue – The consistent and reliable tendency to perform one’s function excellently. When a person has a certain virtue, like courage, they have spent time developing the habit, in this case reacting to danger well, using their human abilities. The virtues then make it possible for us to live a life of flourishing
Sardanapalus – An Assyrian king described by the historian Diodorus as living a life of extreme decadence. Sardanapalus indulged himself with food, alcohol, and many concubines, even going so far to say that physical gratification is the purpose of life. Chrysippus said that, on his tomb is inscribed the following: “Though knowing full well that thou art but mortal, indulge thy desire, find joy in thy feasts. Dead, thou shalt have no delight […] I have only what I have eaten, what wantonness I have committed, what joys I received through passion; but my many rich possessions are now utterly dissolved.”
Function – the characteristic activity of a given thing which makes it what it is. The function of a knife is cutting, while the function of a heart is to pump blood
Eudaimonia – Frequently translated as ‘happiness’, eudaimonia means the attainment of active human flourishing, and is the end Aristotle identifies as humanity’s highest final good
Final Good – A good that we pursue for its own sake. Common examples of final goods include happiness, knowledge, and friendship
Instrumental Good – A good that we pursue for the sake of some other good. A common example is money, as money allows us to purchase other kinds of goods
Anytus – an Athenian politician, war general, and one of the primary accusers behind Socrates’ prosecution. Anytus feared that Socrates would undermine the young Athenian democracy he had helped create and defend
Oracle of Delphi – the high priestess at the temple at Delphi, the oracle was one of the most sought after seers of the ancient world and was thought to relay messages from the god Apollo
Chaerephon – an ancient Greek from the city Sphettus, Chaerephon is remembered as a loyal friend of Socrates, also making an appearance in two other Platonic dialogues, the Charmides and the Gorgias
Meletus – A poet and citizen of Athens and one of Socrates’ accusers. Amongst other things, Meletus accused Socrates of corrupting the youth
Apollo – the ancient sacred site Delphi was dedicated to the god Apollo, an ancient Greek god and the god that Socrates refers to throughout the Apology
Virtue – a character trait, acquired through habitual practice, that enables one to act well. The virtues can also be thought of as excellences of human character, as they make it possible for us to live a life of flourishing. Examples of the virtues include courage, prudence, and justice
The Evil Demon Argument – Argues that we cannot hold any of our beliefs with certainty because we could be radically deceived by an evil demon. A classic argument given by Descartes for doubting the reliability of almost all of our beliefs
Philosophical Skepticism – The position that we do not know many things that we ordinarily take ourselves to know
A Posteriori Knowledge – Knowledge that can only be acquired through having particular, concrete experiences. Such knowledge can be gained simply through our everyday experiences, or through more complex means like controlled scientific experiments
A Priori Knowledge – Knowledge that can be gained without having any particular concrete experiences. Such knowledge is typically gained by rational insight or intuition
Cartesian Method of Doubt – A process employed by René Descartes of rejecting all beliefs that he had at least some reason to doubt in order to see if he had any beliefs that he could know with certainty
Revelation – Theological truths that have been made known by means of some religious text, testimony, authority, or experience, or the act or process in which such truths are made known.
Rationalism – The view that the only reliable means of coming to know truths about God is reason. As a result, what we might otherwise believe by means of faith ought to be disregarded or even rejected in favor of what we must believe by means of reason.
Fideism – The view that the only reliable means of coming to know truths about God is faith. As a result, what we might otherwise believe by means of reason ought to be disregarded or even rejected in favor of what we must believe by means of faith.
Faith – The act of accepting a proposition as true for which there is less than demonstrable evidence, which rises above mere opinion but falls short of logical or scientific demonstration. Faith can also refer to a particular religious tradition or the body of beliefs that are central to that religious tradition.
Virtue – a character trait, acquired through habitual practice, that enables one to act well. The virtues can also be thought of as excellences of human character, as they make it possible for us to live a life of flourishing. Examples of the virtues include courage, prudence, and justice
Socratic Ignorance – an awareness of one’s own ignorance, and the reason that Socrates was deemed wise by the Oracle of Delphi. A person who lacks Socratic Ignorance may believe they know many things they actually don’t, leading them to overestimate how well they understand the world
Apology – a formal defense of justification of an action or belief. A Christian apologist, for example, is someone who defends their faith and seeks to justify it through an appeal to reason.
