Epistemology: Introduction to Theory of Knowledge

by Jennifer Nagel & Geoff Pynn

Get to know what knowledge is with an in-depth tour of some of the biggest ideas in recent epistemology.


Jennifer Nagel

My research focuses on knowledge, belief, and our capacities to track these states in ourselves and others. I’m interested in the history of epistemology, both in the Western tradition back to Plato, and in the Classical Indian and Tibetan traditions.  I also work in contemporary philosophy of mind, with special interests in metacognition and mental state attribution.

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Geoff Pynn

Geoff Pynn received his PhD in Philosophy from Yale University, and now teaches philosophy at Elgin Community College. He previously taught at Northern Illinois University for a decade, and before that, taught high school English and mathematics. His passion is engaging the public in philosophical reflection.

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Introduction to Theory of Knowledge

In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) launches our Theory of Knowledge series. We look at the line between knowing and just believing something, focusing on factors like truth and confidence.


The Problem of Skepticism

Is knowledge humanly possible? In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) looks at skeptical arguments, starting with Ancient Greek and Chinese philosophy, and moving forward into contemporary brain-in-a-vat scenarios. We’ll review a variety of reasons to worry that knowledge might be impossible, and we’ll examine the difference between global and local forms of skepticism.


Three Responses to Skepticism

In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) looks at three historically influential responses to the challenge of skepticism. We start with René Descartes’s efforts to prove that God would not let us be chronically deceived. Next, we examine Bertrand Russell’s efforts to disprove the skeptic through a strategy called ‘inference to the best explanation’, and we finish with G. E. Moore’s common sense approach.


New Responses to Skepticism

How do contemporary philosophers respond to the threat of skepticism? In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) reviews the semantic (or meaning-based) theories of Hilary Putnam and David Chalmers, according to which skepticism either self-destructs, or isn’t as scary as you might think. She then examines the defensive approach of Timothy Williamson, an approach whose goal is not to convert you from being a skeptic back into believing in knowledge, but rather to protect you from becoming a skeptic in the first place.


Analyzing Knowledge: 1. The Gettier Problem

Is knowledge the same as justified true belief? In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) discusses a Gettier case, a scenario in which someone has justified true belief but not knowledge. We’ll look at a Gettier case from Edmund Gettier’s famous 1963 paper on this topic, and a structurally similar case from 8th century Classical Indian philosophy.


Analyzing Knowledge: 2. No-False-Lemma and No-Defeater Approaches

If we can’t analyze knowledge simply as justified true belief, can we add one more ingredient to produce a successful analysis? In this Wireless Philosophy video, Jennifer Nagel examines two ‘extra ingredient’ analyses of knowledge: Michael Clark’s ‘no false lemma’ analysis, and the fancier ‘no undefeated defeaters’ analysis of Keith Lehrer and Thomas Paxson.


Analyzing Knowledge: 3. Causal and Reliabilist Theories

Is knowledge a matter of being causally connected to the world in the right way? In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) examines the causal theory of knowledge proposed by Alvin Goldman in 1967, and then discusses the problems with the causal theory that led Goldman to formulate his influential reliabilist theory of knowledge.


Analyzing Knowledge: 4. Tracking Theories

Problems for the causal theory of knowledge led epistemologists to propose that knowledge is a matter of tracking the truth. Fred Dretske and Robert Nozick developed this idea using counterfactual conditions. In this Wireless Philosophy video, Geoff Pynn (Northern Illinois University) examines the tracking idea, considers how it improves on the causal theory, and then discusses some well known objections to the theories advanced by Dretske and Nozick.


'Knowledge First' Epistemology

After many failed attempts to construct an analysis of knowledge, some philosophers began to wonder whether knowledge was resistant to analysis, and why that might be so. In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) looks at the reasons why philosophers like Linda Zagzebski have thought that knowledge can’t be reductively analyzed, and explores the “Knowledge First” approach of Timothy Williamson.


Virtue Epistemology

In this Wireless Philosophy video, Geoff Pynn (Northern Illinois) introduces virtue epistemology, an approach to epistemology that takes intellectual virtue as the central concept in discussions of theory of knowledge. Along the way, he shows how virtue epistemology can provide interesting solutions to some of the problems that we’ve encountered so far in the series.



In this Wireless Philosophy video, Geoff Pynn (Northern Illinois) explains epistemic contextualism, which says that the word “know” is a context-sensitive term. Geoff describes how contextualists claim to dissolve the problem of radical skepticism, and discusses the argument for contextualism from our ordinary linguistic usage.


Intuition: Epistemology

What makes a judgment count as intuitive? How is intuition different from perception and reasoning? In this Wireless Philosophy video, Jennifer Nagel (University of Toronto) examines the nature of intuition and the role played by intuitions in philosophy.