Abstract. Intensionality has generally been of more concern to logicians than intentionality. But also the latter merits their interest. This paper, a contribution to the logic of action, involves both concepts—the former implicitly, the latter explicitly.

The medieval term intentio was originally employed as a translation of the Arabic termma'na, a formin the soul identified with a meaning or a notion, and meant throughout medieval epistemology a natural sign in the soul. Later the Port Royal Logic distinguished between the comprehension and extension of a general term in something of the way in which Mill later distinguished connotation and denotation: whilst the extension is the set of things to which the term applies, its comprehension is the set of attributes which it implies. Sir William Hamilton replaced “comprehension” by “intension”, faultily spelling the word with an “s” by analogy with “extension”. Since then, the term “intentionality” has gone one way, via Brentano to Chisholm, and the word “intensionality” another via Carnap to Quine.