This document discusses sentences and propositions. It defines a sentence as the basic unit of language that can be expressed in different tenses, while a proposition provides a statement that can be evaluated as true or false. Only indicative sentences are considered propositions. Propositions are the basic units of logic and always use present tense. They can explain quantity and quality, unlike sentences. A proposition consists of a subject, predicate, and copula. Propositions are classified as categorical, conditional, or distinctive based on the relationship between terms. Categorical propositions directly relate subjects and predicates and form the basis of deductive arguments. There are four types of categorical propositions defined by whether they are universal or particular, and affirmative or negative.