在现代哲学、逻辑学、语言学中，命题是指一个判断（陈述）的语义（实际表达的概念），这个概念是可以被定义并观察的现象。命题不是指判断（陈述）本身。当相异判断（陈述）具有相同语义的时候，他们表达相同的命题。例如，雪是白的（汉语）和Snow is white（英语）是相异的判断（陈述），但它们表达的命题是相同的。在同一种语言中，两个相异判断（陈述）也可能表达相同命题。例如，刚才的命题也可以说成冰的小结晶是白的，不过，之所以是相同命题，取决于冰的小结晶可视为雪的有效定义。

通常，命题是指闭判断，以区别于开判断，或谓词。在这种情况下，命题不是真的就是假的。哲学学派逻辑实证主义支持这一命题的概念。

The term proposition has a broad use in contemporary philosophy. It is used to refer to some or all of the following: the primary bearers of truth-value, the objects of belief and other "propositional attitudes" (i.e., what is believed, doubted, etc.), the referents of that-clauses and the meanings of declarative sentences. Propositions are the sharable objects of attitudes and the primary bearers of truth and falsity. This stipulation rules out certain candidates for propositions, including thought- and utterance-tokens which are not sharable, and concrete events or facts, which cannot be false.