Philosophy of language explores the relationship between language and reality. In particular, philosophy of language studies issues that cannot be addressed by other fields, like linguistics, or psychology. Major topics in philosophy of language include the nature of meaning, intentionality, reference, the constitution of sentences, concepts, learning, and thought.
The topic that has received the most attention in philosophy of language has been the nature of meaning. They seek to explain what "meaning" is, and what we mean when we talk about meaning. Within this area, issues include: the nature of synonymy, the origins of meaning itself, and our apprehension of meaning. Another project of special interest to philosophers of language is the investigation into composition, or the question of how meaningful units of language are composed of smaller meaningful parts, and the meaning of the whole is derived from the meaning of its parts.
Secondly, they seek to better understand what speakers and listeners do with language in communication, and how it is used socially. Specific interests may include the topics of language learning, language creation, and speech acts.
Thirdly, they would like to know how language relates to the minds of both the speaker and the interpreter. Of specific interest is the grounds for successful translation of words into other words.
Finally, philosophers of language investigate how language and meaning relate to truth and the world. They tend to be less concerned with which sentences are actually true, and more with what kinds of meanings can be true or false. A truth-oriented philosopher of language might wonder whether or not a meaningless sentence can be true or false, or whether or not sentences can express propositions about things that do not exist, rather than the way sentences are used.
It has long been known that there are different parts of speech. One part of the common sentence is the lexical word, which is composed of nouns, verbs, and adjectives. A major question in the field – perhaps the single most important question for formalist and structuralist thinkers – is, "How does the meaning of a sentence emerge out of its parts?"