Language may perform a variety of functions. We employ it to make statements, ask questions, express our emotions, order someone else around, etc. No serious objection can be levied against the view that language performs functions. However, a number of objections can be raised against specific proposals as to what functions language performs, how many, how they should be distinguished, which is the basic one and other proposals of a similar concrete nature. Also, disagreement is fierce over the nature of the relationship between language functions and linguistic form and structure, over the question as to whether an investigation of linguistic structure should take account of language functions, or, if it should, to what degree.

If we have a plank that we, for some reason or other, wish to hammer a nail into, we look around for a hammer. Failing to find one, we look for a suitable stone, an axe, even the leather heel of a shoe. We do not look for a feather, a handful of soil, not even for another plank, for we know that these would all be unsuited to the task of getting the nail in the plank. In our choice of tool we rely on our knowledge of the properties of things; those will do, these will not do for the job in hand. There is an important relationship between the structural properties of things and the functions that we wish these things to perform.