Epistemology: A Collection of Online Resources and Key Quotes

Lennox Johnson Resources

This page aims to make learning about epistemology (the study of knowledge) as easy as possible by bringing together the best articles, podcasts, and videos from across the internet onto one page. To get started, simply choose one of the resources listed below, or browse a selection of key quotes on knowledge at the bottom of the page.

Encyclopedia Articles

This section features articles from the Stanford Encyclopedia of Philosophy and the Internet Encyclopedia of Philosophy. The SEP is probably the most comprehensive online philosophy resource. It features in-depth articles on a huge number of philosophical topics, however, it is aimed at an academic audience and may be too detailed and technical for beginners. The IEP is generally more beginner-friendly but is also considered to be less reliable. Wikipedia is also an option, but it is much less reliable than either of these.

Stanford Encyclopedia of Philosophy

Internet Encyclopedia of Philosophy


This section features short articles from the website 1000-Word Philosophy. These articles are ideal for anyone looking for a shorter or more beginner-friendly introduction to epistemology than the encyclopedia articles listed above.


The Conversation


This section features episodes from the podcasts Philosophy Bites and In Our Time. These are also aimed at a general audience and are a good option for beginners who prefer audio content.

Philosophy Bites

In Our Time

Short Videos (<30 mins)

This section features short videos created by Wireless Philosophy. These are also very beginner-friendly.


This section features online courses on epistemology.

Course Syllabi

This section features a selection of university course syllabi. Browsing course syllabi can be a useful way to find reading recommendations.

Book Recommendations

This section features requests for book recommendations on philosophy forums. These can also be useful to browse when trying to find reading recommendations.


There is only so much that you can learn using free online resources. This section features books that may be useful if you’re looking to learn more about epistemology. This list was created using the books featured in the course syllabi and forum recommendations above.


This section features a selection of key quotes on knowledge.

I know nothing except the fact of my ignorance.

– Socrates, as quoted in Diogenes Laertius, Lives of the Philosophers, bk. 2, Socrates

Meno: How will you enquire, Socrates, into that which you do not know? What will you put forth as the subject of enquiry? And if you find what you want, how will you ever know that this is the thing which you did not know?

Socrates: I know, Meno, what you mean; but just see what a tiresome dispute you are introducing. You argue that man cannot enquire either about that which he knows, or about that which he does not know; for if he knows, he has no need to enquire; and if not, he cannot; for he does not know the very subject about which he is to enquire.

– Plato, Meno, 80B

And now, let me show in a figure how far our nature is enlightened or unenlightened:—Behold! human beings living in an underground den; here they have been from their childhood, and have their legs and necks chained so that they cannot move, and can only see before them, being prevented by the chains from turning round their heads. Above and behind them a fire is blazing at a distance…. They see only their own shadows, or the shadows of one another, which the fire throws on the opposite wall of the cave. To them, the truth would be literally nothing but the shadows of reality.

– Plato, The Republic (edited), 514A

All men by nature desire to know.

– Aristotle, Metaphysics, 980a1

It were far better never to think of investigating the truth at all, than to do so without a method. … Moreover by a method I mean certain and simple rules, such that, if a man observe them accurately, he shall never assume what is false as true, and will never spend his mental efforts to no purpose, but will always gradually increase his knowledge and so arrive at a true understanding of all that does not surpass his powers.

René Descartes, Rules for the Direction of the Mind, IV

The first [rule] was never to accept anything for true which I did not clearly know to be such; that is to say, carefully to avoid precipitancy and prejudice, and to comprise nothing more in my judgement than what was presented to my mind so clearly and distinctly as to exclude all ground of doubt. The second, to divide each of the difficulties under examination into as many parts as possible, and as might be necessary for its adequate solution. The third, to conduct my thoughts in such order that, by commencing with objects the simplest and easiest to know, I might ascend by little and little, and, as it were, step by step, to the knowledge of the more complex; assigning in thought a certain order even to those objects which in their own nature do not stand in a relation of antecedence and sequence. And the last, in every case to make enumerations so complete, and reviews so general, that I might be assured that nothing was omitted.

René Descartes, Discourse on the Method, II

Seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us; and because some men err in reasoning, and fall into paralogisms, even on the simplest matters of geometry, I, convinced that I was as open to error as any other, rejected as false all the reasonings I had hitherto taken for demonstrations; and finally, when I considered that the very same thoughts (presentations) which we experience when awake may also be experienced when we are asleep, while there is at that time not one of them true, I supposed that all the objects (presentations) that had ever entered into my mind when awake, had in them no more truth than the illusions of my dreams. But immediately upon this I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be somewhat; and as I observed that this truth, I think, therefore I am (COGITO ERGO SUM), was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the sceptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search.

René Descartes, Discourse on the Method, pt. 4

No man’s knowledge here can go beyond his experience.

– David Hume, An Essay Concerning Human Understanding, bk. 4, ch. 7, sect. 11

It has hitherto been assumed that our cognition must conform to the objects; … Let us then make the experiment whether we may not be more successful in metaphysics, if we assume that the objects must conform to our cognition.

– Immanuel Kant, Critique of Pure Reason, Preface to the Second Edition

What then is truth? A mobile army of metaphors, metonyms, and anthropomorphisms – in short a sum of human relations, which have been enhanced, transposed, and embellished poetically and rhetorically, and which after long use seem firm, canonical, and obligatory to a people: truths are illusions about which one has forgotten that this is what they are; metaphors which are worn out and without sensuous power; coins which have lost their pictures and now matter only as metal, no longer as coins.

– Friedrich Nietzsche, On Truth and Lie in an Extra-Moral Sense

Pragmatism … asks its usual question. “Grant an idea or belief to be true,” it says, “what concrete difference will its being true make in anyone’s actual life? How will the truth be realized? What experiences will be different from those which would obtain if the belief were false? What, in short, is the truth’s cash-value in experiential terms?” The moment pragmatism asks this question, it sees the answer: true ideas are those that we can assimilate, validate, corroborate and verify. False ideas are those we cannot. That is the practical difference it makes to us to have true ideas; that, therefore, is the meaning of truth, for it is all that truth is known as.

– William James, Pragmatism, Lecture 2

I can prove now, for instance, that two human hands exist. How? By holding up my two hands, and saying, as I make a certain gesture with the right hand, “Here is one hand,” and adding, as I make a certain gesture with the left, “and here is another.” And if, by doing this, I have proved ipso facto the existence of external things, you will all see that I can also do it now in numbers of other ways: there is no need to multiply examples.

– G. E. Moore, Proof of an External World

It is difficult to define knowledge, difficult to decide whether we have any knowledge, and difficult, even if it is conceded that we sometimes have knowledge to discover whether we can ever know that we have knowledge in this or that particular case.

– Bertrand Russell, The Analysis of Mind, Lecture 8

We can never make absolutely certain that our theory is not lost. All we can do is search for the falsity content of our best theory. We do so by trying to refute our theory; that is, by trying to test it severely in the light of all our objective knowledge and all our ingenuity. It is, of course, always possible that our theory may be false even if it passes all these tests; this is allowed for by our search for verisimilitude. But if it passes all these tests then we may have good reason to conjecture that our theory, which as we know has a greater truth content than its predecessor, may have no greater falsity content. And if we fail to refute the new theory, especially in fields in which its predecessor has been refuted, then we can claim this as one of the objective reasons for the conjecture that the new theory is a better approximation of truth than the old theory.

– Karl Popper, Objective Knowledge

The amount of knowledge which we can justify from evidence directly available to us can never be large. The overwhelming proportion of our factual beliefs continue therefore to be held at second hand through trusting others, and in the great majority of cases our trust is placed in the authority of comparatively few people of widely acknowledged standing.

– Michael Polyani, Personal Knowledge

Truth is not by nature free—nor error servile—its production is thoroughly imbued with relations of power.

– Michel Foucault, History of Sexuality, Vol. 1

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