Major problems and sub-fields
Composition and partsA 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?"
Principle of compositionalityMuch about composition of sentences is addressed in the work of linguistics of syntax.
More logic-oriented semantics tend to look towards the principle of compositionality in order to explain the relationship between meaningful parts and whole sentences. The principle of compositionality asserts that a sentence can be understood on the basis of the meaning of the parts of the sentence (words) along with an understanding of its structure.
Problem of universals and compositionOne debate that has captured the interest of many philosophers is the debate over the meaning of universals. One might ask, for example, "when people say the word, "rocks", what do they mean?" Two general answers have emerged to this question. Some have said that the expression stands for some real entity out in the world called "rocks". Others have said that it stands for some collection of particular rocks that we put into a common category. The former position has been called philosophical realism, and the latter has been called nominalism.
From the radical realist's perspective, the connection between S and M is a connection between two abstract entities. There is an entity, "man", and an entity, "Socrates". These two things connect together in some way or overlap one another. Plato's theory of forms was an instance of this.
From a nominalist's perspective, the connection between S and M is the connection between a particular entity (Socrates) and a vast collection of particular things (men). To say that Socrates is a man is to say that Socrates is a part of the class of "men".
Another perspective is to consider "man" to be a property of the entity, "Socrates". A property is a characteristic of the thing.
Still another perspective considers "man" to be the product of a propositional function. A propositional function is an operation of language that takes an entity (Socrates) and outputs a proposition. In other words, a propositional function is like an algorithm. The meaning of man is whatever takes the entity, "Socrates", and turns it into the statement, "Socrates is a man".
The nature of meaningThe answer to the question, "What is the meaning of meaning?", is not immediately obvious. One section of philosophy of language tries to answer this very question.
Types of meaningGeoffrey Leech posited that there are two essentially different types of linguistic meaning: conceptual and associative.
The conceptual meanings of an expression have to do with the definitions of words themselves, and the features of those definitions. This kind of meaning is treated by using a technique called the semantic feature analysis. The conceptual meaning of an expression inevitably involves both definition (also called "connotation" and "intension" in the literature) and extension (also called "denotation").
The associative meaning of an expression has to do with individual mental understandings of the speaker. They, in turn, can be broken up into six sub-types: connotative, collocative, social, affective, reflected and thematic (Mwihaki 2004).
Theories of meaningThe question, "What is the meaning of 'meaning'?", may not have an obvious answer. Philosophers of language have tried to give their accounts. Generally speaking, there have been at least four different kinds of attempts at explaining what a linguistic "meaning" is. Idea theories of meaning, most commonly associated with the empiricist tradition, emphasize that meanings are thoughts provoked by signs. Truth-conditional theories hold meaning to be the conditions under which an expression may be true or false. Meaning as usage perspectives understand meaning to involve or be related to speech acts and particular utterances, not expressions themselves. Finally, Reference theories of meaning view meaning to be equivalent to those things in the world that are actually connected to signs.
Other theories exist to discuss non-linguistic meaning (i.e., meaning as conveyed by body language, meanings as consequences, etc.)
Puzzles for accounts of meaningOne issue that has bothered philosophers of language and logic is the problem of the vagueness of words (or uses). Often, meanings expressed by the speaker are not as explicit as the listener would like them to be. The consequences of vagueness can be disastrous to classical logic because they give rise to the Paradox of the heap.
Language and the worldInvestigations into how language interacts with the world are called "theories of reference".
* Gottlob Frege was an advocate of a mediated reference theory, which appealed to the sense of a referring expression (the sense being the way the referent is presented).
* By contrast, in response to British idealism, Bertrand Russell sought to scrap all "unreal" things from language. To do this, he created a direct reference theory.
Frege's mediated reference theory seems to differ from Russell's direct reference theory in that logically proper names, on Russell's account, had no meaning but their referent. On Frege's account, any referring expression had a sense as well as a reference. Co-referential names, such as "Samuel Clemens" and "Mark Twain" cause problems for a directly referential view (though, not all versions of Russell's theory, because, for Russell, not all grammatically proper names were logically proper). Frege's view encounters difficulties in spelling out the specifics of senses.
Mind and language