wise%SEISMO@cal-unix.UUCP (09/27/83)
A side light to the discussions of the halting problem is "what then?" What do we do when a loop is detected? Ignore the information? Arbitrarily select some level as the *true* meaning? In some cases, meaning is drawn from outside the language. As an example, consider a person who tells you, "I don't know a secret". The person may really know a secret but doesn't want you to know, or may not know a secret and reason that you'll assume that nobody with a secret would say something so suspicious ... A reasonable assumption would be that if the person said nothing, you'd have no reason to think he knows a secret, so if that was the assumption which he desired for you to make, he would just have kept quiet, so you may conclude that the person knows no secret. This rather simplistic example demonstrates one response to the loop, i.e., when confronted with circular logic, we disregard it. Another possibility is that we may use external information to attempt to help dis-ambiguate by selecting a level of the loop. (e.g. this is a three-year-old, who is sufficiently unsophisticated that he may say the above when he does, in fact, know a secret.) This may support the study of cognition as an underpinning for NLP. Certainly we can never expect a machine to react as we (who is 'we'?) do unless we know how we react.