Status Updates From An Introduction to the Theo...

Mere belief, then, is not sufficient for knowledge. Knowledge requires that one’s belief be true.
D2 S knows that p 1⁄4Df. (1) S believes that p and (2) p is true.
D2 tells us that one knows that p if and only if one has a true belief that p. D2 says that having a true belief that p is sufficient for one’s knowing that p. But this, too, is clearly mistaken. One might have a true belief that is not knowledge.

According 2 1 traditional view, to have propositional knowledge that p is to have epistemically justified true belief that p. Before we consider this traditional view, let us begin by considering the following clearly mistaken view:
D1 S knows that p = Df. S believes that p.
According to D1, believing something is sufficient for knowing it. If D1 were true, then someone who believed a false proposition would know it.

Among the three most significant are (1) propositional knowledge, (2) acquaintance knowledge, and (3) ‘‘how to’’ knowledge.

(5) John knows how to play a piano sonata implies
(6) John has the ability to play a piano sonata.

It is important to distinguish between sentences and propositions. Paul would say, ‘‘The sky is blue,’’ and Pierre would say, ‘‘Le ciel est bleu.’’ Though each expresses his belief by a different sentence, each believes the same proposition.

Propositional knowledge is knowledge of facts or true propositions. So, consider the following examples of propositional knowledge:
(1) John knows that Caesar was assassinated. (2) John knows that the sky is blue.
In these examples, the objects of knowledge, or what is known, are, respectively, the true propositions that Caesar was assassinated and that the sky is blue.