Crítica, Revista Hispanoamericana de Filosofía, Volume 13, number 38, August 1981
Prescripciones y normas: la teoría de Castañeda
[Prescriptions and Norms: Castañeda's Theory]
Carlos E. Alchourrón
Universidad de Buenos Aires


This paper is about H.N. Castañeda’s theory of practical thinking. His theory includes a deontic logic and a logic for practitions (the conceptual kernel of prescriptions and intentions). Castañeda presents both logics in an axiomatic form justified by a correlative semantic approach. In this paper I wish to argue that many theorems of the syntactic presentations are semantically invalid; and, moreover, that many semantically valid expressions do not appear in the corresponding calculi because they are not even formulable in them. This lack of correlation gives rise to many specific problems. In particular, it is shown that the formulas used by Castañeda to solve some classical deontic paradoxes are invalid according to his own standards, and that the paradoxes reappear in his logic because there are some valid formulas that the author has never made explicit.

Although Castañeda rejects Hume’s thesis that ought-judgments are not implied by premises among which there are no ought-judgments, his semantic explanation of deontic propositions and practitions supports Hume’s thesis.

In the last part of the paper it is argued that Castañeda’s acceptance of Kant’s principle that ought implies can does not agree with the author’s main conception of deontic propositions. For this acceptance he is led to reconstruct conflicts of obligation in an unnecessary and artificial way.

These difficulties result from the fact that Castañeda has built not one but at least two different deontic logics based upon two different logics for practitions. All of these logics are supported by powerful and important intuitions, but it is necessary to introduce some modifications in order to eliminate the conflicting features of the theory as a whole.


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