Peter Pagin

Some theories of linguistic meaning, such as those of Paul Grice and David Lewis, make appeal to higher–order thoughts: thoughts about thoughts. Because of this, such theories run the risk of being empirically refuted by the existence of speakers who lack, completely or to a high degree, the capacity of thinking about thoughts. Research on autism during the past 15 years provides strong evidence for the existence of such speakers. Some persons with autism have linguistic abilities that qualify them as speakers, but manifest a severely impaired capacity to understand what it is to have beliefs.

Suppose you are stranded on an island and you want to get over to the nearby mainland. Your only option is to swim. But is the other shore close enough? If you embark and it isn’t, you drown. So you prefer to know before taking off. Happily, you are well equipped. You have not only a yardstick, but also a theodolite for measuring angles, and a good knowledge of trigonometry. You then determine the distance to the other shore by means of triangulation. You fix two points, A and B, on your own shore, and identify a third point, C, in sight on the opposite shore. You then measure the distance between A and B with your yardstick, and the two angles ABC and CAB with your theodolite. With this information you can calculate the distances AC and BC to the other shore.

However, if Wittgenstein’s so called rule-following considerations are correct, then this reason for believing in the validity of (C), is mistaken. The conclusion of those considerations is that we must reject the idea that rules are things which determine possible cases of application before those cases are actually encountered and decided by speakers. If this is right, then there is no rule which determines the meanings of new sentences, i.e. before those sentences have actually been used. Therefore, it might seem that (C) is not valid for natural languages.