Epistemology is the study of knowledge. Its central questions include “What is knowledge?” and “Is knowledge possible?”. This post tries to give an overview of the field highlighting key terminology, open problems, and categories of responses to those problems.
Epistemology is the study of knowledge.
For literally millenia, people were content to think of knowledge as justified true belief (Plato 360BC). Let’s break that down briefly:
- A belief is mental content held as true. Thinking to myself, with conviction, “I am a human.” and “I am a dragon.” are each equally examples of beliefs.
- Alas, only one of the above claims is true. Even if I have very convincing hallucinations of breathing fire and flying, “I am a dragon” is merely justified belief. It’s not true and so not knowledge.
- On the other hand, if I stumble onto true belief, it still doesn’t count as knowledge. If you roll a 100-sided die and hide the result under a cup, I don’t know that the result is 64 even if I believe it and it turns out to be true—I have no justification for the belief.
It’s only when beliefs are both true and justified that they count as knowledge. Sounds reasonable, right?
Not to Edmund Gettier. In a three page paper (Gettier 1963), he presented two compelling counterexamples to this analysis. An example of this vein of anecdote is:
Whetu is driving home from work one day and happens to see her coworker Sigrún in a Vanagon. She thinks to herself, “Ah, one of my coworkers owns a Vanagon.” However, unbeknownst to Whetu, Sigrún does not actually own the Vanagon she was driving—she was in the midst of stealing it. But, coincidentally, one of Whetu’s other coworkers does own a Vanagon.
So Whetu’s initial belief—“One of my coworkers owns a Vanagon”—turns out to be true and justified (we’ll count seeing someone driving a car as convincing justification for believing that they own it). But intuitively, we’re reluctant to accept that Whetu knows that one of her coworkers owns a Vanagon. It seems like she just got lucky—her mistaken justification was rescued by a fact that she would be surprised to learn.