2 What Is Knowledge?
Explore the kinds of knowledge, the traditional justified-true-belief analysis, and why Gettier cases have made the definition of knowledge a continuing philosophical debate.
Knowledge and lucky truth
A correct thought is not automatically knowledge. Someone might guess correctly, repeat a rumor, or rely on faulty evidence and arrive at a true belief by chance. asks what distinguishes knowing from believing something true by luck.
Three kinds of knowledge
Philosophers commonly distinguish three kinds of knowledge. These categories can overlap, but each highlights a different way of knowing.
is knowing that a particular claim is true. The claim following “that” is a proposition: something that can be true or false. For example, Maya knows that water freezes at 0°C under standard atmospheric pressure, and Omar knows that the library is open. Philosophical analysis of knowledge has traditionally focused chiefly on this kind.
, or know-how, is the ability or competence to perform an activity. Examples include knowing how to swim, solve a Rubik’s Cube, or ride a bicycle. It is often demonstrated through successful performance rather than by stating facts. Knowing how to swim may involve knowing facts about breathing and movement, but whether know-how can be reduced entirely to knowledge-that is disputed: some philosophers treat it as a distinctive ability, while others hold that it depends on knowledge of relevant propositions.
is familiarity with a person, place, or experience. Examples include knowing a neighbor, knowing a city through having visited it, or being directly familiar with the taste of lemon. Reading about Paris is not the same as being acquainted with the city. The categories can overlap: someone who has visited Paris may know the city by acquaintance and also know propositions about its streets and history.
The justified-true-belief account
The account, often abbreviated JTB, is a traditional starting point for analyzing . According to this account, a person knows a proposition if and only if three conditions are met:
The proposition is true; one cannot know a falsehood.
The person believes the proposition; a person generally cannot know a claim while not believing it.
The person is justified in believing it, because the belief is supported by adequate evidence or formed through an appropriate method rather than being a mere guess.
For example, Lena checks a reliable weather report and concludes that it is raining. If it really is raining, her true belief appears well supported. The JTB account aims to explain why this is knowledge while a lucky guess that it is raining is not. Its three conditions capture important features of knowledge, but whether they are sufficient has been challenged.
Why may fall short
In 1963, Edmund Gettier presented cases intended to show that does not always amount to knowledge. In a typical , a person has good reason to believe something, the belief is true, but its truth depends on an accident unrelated to the evidence. The person appears to get the right answer for the wrong reason.
In the stopped-clock example, Priya looks at a clock that has always worked reliably and sees that it reads 3:00. She reasonably believes that it is 3:00. Unknown to her, the clock stopped exactly twelve hours earlier. By coincidence, it really is 3:00 when she looks.
Priya believes the time, her belief is true, and it seems justified. Yet it seems she does not know the time, because the clock gives the correct reading only by coincidence. Had she looked at almost any other time, she would have formed a false belief. The example suggests that justification can coexist with that prevents knowledge, so truth, belief, and justification together may not be sufficient. It does not show that any of those three conditions is irrelevant; it raises the question of what further connection between a belief and the truth is needed.
Proposed responses to Gettier cases
Several influential approaches try to improve on the JTB account, but none is a settled definition accepted by everyone, and no single analysis has resolved every version of the Gettier problem.
No-false-grounds condition: A belief is not knowledge if its justification essentially depends on a false assumption. This handles some Gettier cases, but philosophers have developed cases that appear to challenge this fix as well.
Reliable process: A reliabilist approach requires that the belief be produced by a process that tends to yield true beliefs, such as ordinary vision in suitable conditions. This shifts attention from whether the believer can identify strong evidence to how the belief was actually formed.
: A belief may count as knowledge if it would vary appropriately with the truth. For example, the person would not have held the belief had it been false. Different accounts specify this requirement in different ways.
Intellectual ability: connect knowledge to reliable intellectual abilities, such as careful observation or sound reasoning, rather than to luck.
Each approach aims to explain why knowledge is more than a true belief that happens to have some justification.