The problem of knowledge: the distinction between knowledge and belief, the justified true belief account of knowledge, the sources of knowledge (reason and sense experience), and the sceptical challenge that we cannot be certain of what we claim to know.

What this dot point is asking

Knowledge and Doubt is the epistemology area of Higher Philosophy: it asks what knowledge is and whether we can really have it. This first dot point sets up the problem. You must explain how knowledge differs from belief, state the justified true belief account, identify the two main sources of knowledge (reason and sense experience), and explain the sceptical challenge that drives the whole topic.

Knowledge versus belief

The point of the distinction is that we want knowledge, not mere opinion. You can sincerely believe a false claim, and you can believe a true claim for no good reason. Neither counts as knowing. Knowledge picks out beliefs that are both true and properly grounded.

The justified true belief account

The justification condition is doing the crucial work: it rules out true beliefs that are held by luck. If you guess that a coin will land heads and it does, you had a true belief but no knowledge, because you had no adequate justification. This is also the condition the sceptic attacks, by arguing that we never have justification strong enough to be certain.

Sources of knowledge

The two traditional sources of knowledge frame the whole area:

• Reason (a priori). Knowledge gained by thinking alone, independently of experience. "All bachelors are unmarried" and the truths of mathematics are known a priori. Rationalists give reason the leading role.
• Sense experience (a posteriori). Knowledge gained through the senses: sight, hearing, touch and so on. "Snow is cold" is known a posteriori. Empiricists give experience the leading role.

This split between rationalism and empiricism is exactly what the next dot points examine, through Descartes (reason) and Hume (experience).

The sceptical challenge

The sceptic's tools are doubts about our sources. The senses sometimes deceive (a straight stick looks bent in water). We cannot always tell waking from dreaming. And in the most radical form, an evil demon, or a modern equivalent such as a brain in a vat or a simulation, could be feeding us systematically false experiences. If we cannot rule these out, we cannot be certain that even our most ordinary beliefs are true, and so, the sceptic says, we cannot claim to know. Every theory of knowledge in this area is in part a response to scepticism.

Examples in context

Suppose you say "I know there is a tree outside the window." Test it against JTB: you believe it, and (let us suppose) it is true, but what is your justification? You see the tree. The sceptic now presses: could your senses be wrong, could you be dreaming, could an evil demon be deceiving you? If you cannot rule these out, your justification is not certain, so on a strict standard you do not know there is a tree, you only have a strongly held, probably true belief. This shows how the sceptic targets condition (3): not the truth of the claim or your sincerity, but whether your grounds are good enough for knowledge. Descartes' reply will be to find a belief that survives even this doubt.

Try this

Q1. State the three conditions of the justified true belief account of knowledge. [3 marks]

• Cue. To know that P: you must believe that P, P must be true, and you must have adequate justification for believing that P.

Q2. Give one example of a sceptical doubt about a source of knowledge. [2 marks]

• Cue. The senses can deceive (a stick looks bent in water), we cannot always tell we are not dreaming, or an evil demon or simulation could be feeding us false experiences.