The subject of this paper, Excuses, is one not to be treated, but only to be introduced, within such limits. It is, or might be, the name of a whole branch, even a ramiculated branch, of philosophy, or at least of one fashion of philosophy. I shall try, therefore, first to state what the subject is, why it is worth studying, and how it may be studied, all this at a regrettably lofty level: and then I shall illustrate, in more (...) congenial but desultory detail, some of the methods to be used, together with their limitations, and some of the unexpected results to be expected and lessons to be learned. Much, of course, of the amusement, and of the instruction, comes in drawing the coverts of the microglot, in hounding down the minutiae, and to this I can do no more here than incite you. But I owe it to the subject to say, that it has long afforded me what philosophy is so often thought, and made, barren of -- the fun of discovery, the pleasures of co-operation, and the satisfaction of reaching agreement. (shrink)

It is argued that the traditional distinction between artificial intelligence and cognitive simulation amounts to little more than a difference in style of research - a different ordering in goal priorities and different methodological allegiances. Both enterprises are constrained by empirical considerations and both are directed at understanding classes of tasks that are defined by essentially psychological criteria. Because of the different ordering of priorities, however, they occasionally take somewhat different stands on such issues as the power/generality trade-off and on (...) the relevance of the sort of data collected in experimental psychology laboratories. (shrink)

This is a philosophical `position paper' (html and pdf versions), starting from the observation that we have an intuitive grasp of a family of related concepts of ``possibility'', ``causation'' and ``constraint'' which we often use in thinking about complex mechanisms, and perhaps also in perceptual processes, which according to Gibson are primarily concerned with detecting positive and negative affordances, such as support, obstruction, graspability, etc. We are able to talk about, think about, and perceive possibilities, such as possible shapes, possible (...) pressures, possible motions, and also risks, opportunities and dangers. We can also think about constraints linking such possibilities. If such abilities are useful to us (and perhaps other animals) they may be equally useful to intelligent artefacts. All this bears on a collection of different more technical topics, including modal logic, constraint analysis, qualitative reasoning, naive physics, the analysis of functionality, and the modelling design processes. The paper suggests that our ability to use knowledge about ``de-re'' modality is more primitive than the ability to use ``de-dicto'' modalities, in which modal operators are applied to sentences. The paper explores these ideas, links them to notions of ``causation'' and ``machine'', suggests that they are applicable to virtual or abstract machines as well as physical machines. Some conclusions are drawn regarding the nature of mind and consciousness. (shrink)