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What Epistemology Studies
Q: What is the object of study here? That is, what is knowledge?
A: Two types - Propositional & Practical

Propositional knowledge = knowledge of facts (dogs have four legs)

Practical knowledge = knowhow, know how to do something – and is in many cases unconscious (one does not have to consider how to walk down a flight of stairs)

—- Heidegger views practical as more fundamental than propositional (leans toward pragmatism) – tried to arrival at propositional knowledge about practical knowledge.

Acquisition of Knowledge
Q: How do we know? How do we attain knowledge?
A: Two main approaches provided: Empiricism & Rationalism

Sense or experience – Empiricists (however, information is deceiving via senses alone)
List of some Empiricists

A posteriori knowledge is knowledge that is known by experience (that is, it is empirical, or arrived at afterward).

Niccolò Machiavelli

Leonardo da Vinci (1452–1519) said:
If you find from your own experience that something is a fact and it contradicts what some authority has written down, then you must abandon the authority and base your reasoning on your own findings.

Seeing the Body: The Divergence of Ancient Chinese and Western Medical Illustration”, Camillia Matuk, Journal of Biocommunication, VOl. 32, No. 1, 2006

John Locke
An Essay Concerning Human Understanding (1689) proposed the view wherein the only knowledge humans can have is a posteriori, i.e., based upon experience. Locke is famously attributed with holding the proposition that the human mind is a tabula rasa, a “blank tablet,” in Locke’s words “white paper,” on which the experiences derived from sense impressions as a person’s life proceeds are written.

George Berkeley

Afraid Locke’s view opened a door that would lead to eventual atheism responded in his Treatise Concerning the Principles of Human Knowledge (1710) an important challenge to empiricism in which things only exist either as a result of their being perceived, or by virtue of the fact that they are an entity doing the perceiving. (For Berkeley, God fills in for humans by doing the perceiving whenever humans are not around to do it). In his text Alciphron, Berkeley maintained that any order humans may see in nature is the language or handwriting of God. Berkeley’s approach to empiricism would later come to be called subjective idealism.

David Hume

Moved empiricism to a new level of skepticism. Hume argued in keeping with the empiricist view that all knowledge derives from sense experience, but he accepted that this has implications not normally acceptable to philosophers. He wrote for example, “Mr. Locke divides all arguments into demonstrative and probable. In this view, we must say, that it is only probable all men must die, or that the sun will rise to-morrow.”And, “Mr. Locke, in his chapter of power, says that, finding from experience, that there are several new productions in nature, and concluding that there must somewhere be a power capable of producing them, we arrive at last by this reasoning at the idea of power. But no reasoning can ever give us a new, original, simple idea; as this philosopher himself confesses. This, therefore, can never be the origin of that idea.”

Francis Bacon (Father of Empiricism)
Advancement of Learning (1605),

Thomas Hobbs

The Pragmatists:

The ideas of pragmatism, in its various forms, developed mainly from discussions that took place while Charles Sanders Peirce and William James were both at Harvard in the 1870s. James popularized the term “pragmatism”. This perspective integrates the basic insights of empirical (experience-based) and rational (concept-based) thinking into that which is pragmatic.

John Dewey

Knowledge can be obtained via reasoning – Rationalists, who believe the limited sense can be overcome. List of some Rationalists

A priori knowledge is knowledge that is known independently of experience (that is, it is non-empirical, or arrived at beforehand, usually by reason). It will henceforth be acquired through anything that is independent from experience.

Pythagoras (570–495 BCE)[edit]
Main article: Pythagoras
One of the first Western philosophers to stress rationalist insight. He “believed these harmonies reflected the ultimate nature of reality. He summed up the implied metaphysical rationalism in the words “All is number.”

Plato (427–347 BCE)
Held rational insight to a very high standard, as is seen in his works such as Meno and The Republic. He taught on the Theory of Forms (or the Theory of Ideas) which asserts that non-material abstract forms (or ideas), and not the material world of change known to us through sensation, possess the highest and most fundamental kind of reality. Plato’s forms are accessible only to reason and not to sense.

Aristotle (384–322 BCE)
Aristotle has a process of reasoning similar to that of Plato’s, though he ultimately disagreed with the specifics of Plato’s forms. Aristotle’s great contribution to rationalist thinking comes from his use of syllogistic logic. Aristotle defines syllogism as “a discourse in which certain (specific) things having been supposed, something different from the things supposed results of necessity because these things are so.” Despite this very general definition, Aristotle limits himself to categorical syllogisms which consist of three categorical propositions in his work Prior Analytics. These included categorical modal syllogisms.

After Aristotle’s death, no great leaps in Western rationalistic thought occurred for the next 1,800 years. The only notable event in the Western timelime was the philosophy of St. Thomas Aquinas who attempted to merge Greek rationalism and Christian revelation in the thirteenth-century.

René Descartes (1596–1650)
Descartes is the first of the modern rationalists and has been dubbed the Father of Modern Philosophy.

Descartes thought that only knowledge of eternal truths – including the truths of mathematics, and the epistemological and metaphysical foundations of the sciences – could be attained by reason alone; other knowledge, the knowledge of physics, required experience of the world, aided by the scientific method.

He elaborated these beliefs in such works as Discourse on Method, Meditations on First Philosophy, and Principles of Philosophy.

Descartes developed a method to attain truths according to which nothing that cannot be recognised by the intellect (or reason) can be classified as knowledge. These truths are gained “without any sensory experience,” according to Descartes. Truths that are attained by reason are broken down into elements that intuition can grasp, which, through a purely deductive process, will result in clear truths about reality.

Descartes therefore argued, as a result of his method, that reason alone determined knowledge, and that this could be done independently of the senses. For instance, his famous dictum, cogito ergo sum or “I think, therefore I am,” is a conclusion reached a priori i.e., prior to any kind of experience on the matter. The simple meaning is that doubting one’s existence, in and of itself, proves that an “I” exists to do the thinking. In other words, doubting one’s own doubting is absurd.

Baruch Spinoza (1632–1677)[edit]
Spinoza’s philosophy is a system of ideas constructed upon basic building blocks with an internal consistency with which he tried to answer life’s major questions and in which he proposed that “God exists only philosophically.” He was heavily influenced by thinkers such as Descartes, Euclid and Thomas Hobbes, and Maimonides. Spinoza’s philosophy attracted believers such as Albert Einstein and much intellectual attention.

Gottfried Leibniz (1646–1716)
Leibniz was the last of the great Rationalists who contributed heavily to other fields. Leibniz rejected Cartesian dualism and denied the existence of a material world. In Leibniz’s view there are infinitely many simple substances, which he called “monads”.
Leibniz developed his theory of monads in response to both Descartes and Spinoza. In rejecting this response he was forced to arrive at his own solution. Monads are the fundamental unit of reality, according to Leibniz, constituting both inanimate and animate things. These units of reality represent the universe, though they are not subject to the laws of causality or space (which he called “well-founded phenomena”). Leibniz, therefore, introduced his principle of pre-established harmony to account for apparent causality in the world.

Immanuel Kant (1724–1804)
Argued that human perception structures natural laws, and that reason is the source of morality.
Kant named his branch of epistemology Transcendental Idealism, and he first laid out these views in his famous work The Critique of Pure Reason. In it he argued that there were fundamental problems with both rationalist and empiricist dogma. To the rationalists he argued, broadly, that pure reason is flawed when it goes beyond its limits and claims to know those things that are necessarily beyond the realm of all possible experience:. Kant referred to these objects as “The Thing in Itself” and goes on to argue that their status as objects beyond all possible experience by definition means we cannot know them. To the empiricist he argued that while it is correct that experience is fundamentally necessary for human knowledge, reason is necessary for processing that experience into coherent thought. He therefore concludes that both reason and experience are necessary for human knowledge. In the same way, Kant also argued that it was wrong to regard thought as mere analysis. In Kant’s views, a priori concepts do exist, but if they are to lead to the amplification of knowledge, they must be brought into relation with empirical data.”

Galileo (1564–1642)

Q: How does knowledge differ from belief?//How is knowledge different than opinion or belief?

Condition 1: Mere belief is not sufficient for knowledge.

Condition 2: Knowing propositional knowledge is not an activity but a condition of relation to information. – JTB. When one comes to this relation with information is JTB –

Condition 3: One must have good reason for the belief.

Condition 4: One must have conscious knowledge of the justification and rational for their belief, guesses, conjecture, and opinions are not validations.

What is Belief here?

Belief – The blind acceptance of a proposition. (This is the most familiar use of the term)

Belief – acceptances as true of any cognitive content. To believe is to accept as true.

I believe the earth rotates the sun – I know the earth rotates the sun
Deontological, non-deontological
Evidence vs reliability
Internal vs external

Justified True Belief:

The concept of justified true belief states that in order to know that a given proposition is true, one must not only believe the relevant true proposition, but one must also have justification for doing so. In more formal terms, a subject S knows that a proposition P is true if and only if:
P is true
S believes that P is true, and
S is justified in believing that P is true

Justification and the Regress Problem:

“… to justify a belief one must appeal to a further justified belief. This means that one of two things can be the case. Either there are some [epistemologically basic] beliefs that we can be justified for holding, without being able to justify them on the basis of any other belief, or else for each justified belief there is an infinite regress of (potential) justification [the nebula theory]. On this theory there is no rock bottom of justification. Justification just meanders in and out through our network of beliefs, stopping nowhere.


Foundationalism - Self-evident basic beliefs justify other non-basic beliefs.

Asserts that certain “foundations” or “basic beliefs” support other beliefs but do not themselves require justification from other beliefs. These beliefs might be justified because they are self-evident, infallible, or derive from reliable cognitive mechanisms. Perception, memory, and a priori intuition are often considered to be possible examples of basic beliefs.
The chief criticism of foundationalism is that if a belief is not supported by other beliefs, accepting it may be arbitrary or unjustified,[25] though foundationalism is based upon the principle that these beliefs are infallible enough to be recognised as such in practice.

Coherentism - Beliefs are justified if they cohere with other beliefs a person holds, each belief is justified if it coheres with the overall system of beliefs.

rejection of the assumption that the regress proceeds according to a pattern of linear justification. To avoid the charge of circularity, coherentists hold that an individual belief is justified circularly by the way it fits together (coheres) with the rest of the belief system of which it is a part. This theory has the advantage of avoiding the infinite regress without claiming special, possibly arbitrary status for some particular class of beliefs. Yet, since a system can be coherent while also being wrong, coherentists face the difficulty of ensuring that the whole system corresponds to reality.

The Idea of Satan does not cohere with other information we have about the world

Infinitism - Beliefs are justified by infinite chains of reasons.

It is not impossible for an infinite justificatory series to exist.

Other Famous Epidemiologists

Ayn Rand
Jean Piaget
John Locke
David Hume
Immanuel Kant
Søren Kierkegaard
René Descartes
Noam Chomsky

Other approaches to the acquisition of knowledge


  • Fallibilism is the view that knowing something does not entail certainty regarding it. Karl Popper. Logik Der Forschung (The Logic of Scientific Discovery), 1934


Cognition and Evaluation – leads to knowledge
Empirical date and Reasoned Evaluation

Why Study Epistemology?

Should we ever like to discern the reality around us we must have a framework for engaging it

Dogmatists – assume we can know the world objectively