EDITOK'S INTKODUCTION

The concept of action has already been studied extensively in both philos- ophy and theoretical computer science. By comparison, the development of the philosophical logic of action lags far behind. The present issue has been put together in order to stimulate the interest in this emerging field among philosophical logicians and to call attention to the exciting possibilities it offers.

The papers may be divided into two groups. The first three are of a more or less systematic nature. Segerberg gives an account of some historically important work whereas Sylvan's contribution, which is both critical and historical, looks to the future as well as to the past. Castafieda carries out a philosophical analysis of action which - - if terms are stretched a bit - - may be regarded as an example of logic of action without formulas. The five papers in the second group are more specialized. Belnap and Perloff add yet another to their series of papers exploring their concept of STIT ("seeing to it that") while Chellas tries to accommodate that concept within his own theoretical framework. Brown continues his analysis of the concept of ability in a possible-worlds setting. Segerberg's and Goldblatt's papers are in the dynamic logical tradition: the former has another go at his delta operator, and the latter shows how to adapt the filtration method so as to prove a completeness theorem in dynamic logic with concurrent action.

The concluding bibliography is no doubt incomplete by almost any stan- dard and should be regarded as a stopgap while we are waiting for a more definitive bibliography.

Hector-Neri Castafieda's recent death is a great loss to philosophy and philosophical logic. This issue is respectfully dedicated to his memory.

K. S.

Dolgue, Claret 28 May 1992