There is no definite agreement about what semantics is, but the view semantic externalism supposes an answer. According to semantic externalism, the field of semantics is the study of words and their relationship to the world. If this conception is correct, the goal of semantics ought to be to discover what this relationship may be.
Semantic externalism is opposed to semantic internalism. Semantic internalists accept no such relationship as that between words and aspects of the world. As Steven Gross writes in "(Descriptive) Externalism in semantics,"
Internalist opponents maintain that semantics rather concerns, or ought to concern, only non-intentional relations among linguistic items and (other) mental structures... On their view, semantics lays out what concepts or thoughts expressions directly activate or express, without recourse to intentional relations to things external to the mind/brain.The grand question that externalists seek to provide an answer to, Gross writes, is: "Should semantics include a characterization of intentional relations between linguistic items and aspects of the world?"
The internalist answer is no, and here it might be useful checking why. On many different grounds, internalists can be opposed to this word-world relation. Here are some examples that provide reasons to be skeptical of this conception of semantics.
If semantic externalism is true, it is unclear how we can say a river, which is supposed to have some real-world properties apart from the human mind, can dry up, be diverted, frozen over and become a road, and so on. This gives some credence to the fact that the meaning of river has more to do with what goes on in the head than with some external property that all rivers might have. River might be more a concept like Texas, which, if it has any properties at all, are the properties constructed by the human mind/brain and which have nothing to do with any necessary relationship between the words themselves and something in the world.
There are more examples. Take this sentence: "The book John wrote weighs two pounds." Somehow the book in this sentence is both an abstract and a concrete object. The concrete object weighs two pounds. The abstract object is what John wrote and may not be any particular book.
Another kind of word or concept for which it is difficult to find what the real-world correlate would be is something like the average American. What object in the world corresponds to the average American?
Or take fictional creatures. It is very unclear to see how Superman is supposed to be any particular object in the world, and yet it is perfectly intelligible what we mean when we talk about Superman. Yet it does not seem as though there is any way to make sense of the expression, "Superman is Clark Kent," if in the world there is no Superman and no Clark Kent.
How might semantic externalists reply? We'll take that up next time.