Final answer:
A proposition is a statement that can be identified as either true or false, and is key to the field of epistemology. Propositional knowledge can be either a priori, gained through reason, or a posteriori, through experience. The truth of a proposition depends on its correspondence to reality or facts.
Step-by-step explanation:
A proposition is defined as a unit of knowledge that can be true or false. It is a statement about the world that carries a truth value, and as such, they are declarative sentences to which we can ascribe the labels 'true' or 'false', hence they claim a certain status of verifiability. Propositions are central to the field of epistemology, the study of knowledge, where they are often characterized as 'knowledge that' since they are expressed in sentences that can be known to be true or false.
Propositional knowledge is further classified as either a priori or a posteriori. A priori knowledge can be gained through reason alone, such as mathematical truths, while a posteriori knowledge is derived from experience, such as knowing the height of oneself or the capital of a country. The way we acquire propositional knowledge differs, but the essence is that it consists of claims about the world which we come to identify as facts.
The truth of a proposition is often contextualized through its conformity with reality or facts, aligning with theories that assert 'a sentence is true if it corresponds to the factual state of affairs'. Hence, our recognition and acceptance of certain propositions as true or false form the basis of propositional knowledge.