 Within analytic philosophy, intentionalism is a generalisation of an idea presented by G.E.M. Anscombe (1965), and the “belief theories” of D.M. Armstrong (1968) and George Pitcher (1970). (Within the phenomenological tradition intentionality and perception had always been discussed together: see the entry on  phenomenology.)  Anscombe had drawn attention to the fact that perceptual verbs satisfy the tests for non-extensionality or intensionality (see the entry on  intensional transitive verbs).  For example, just as ‘Vladimir is thinking about Pegasus’ is an intensional context, so ‘Vladimir has an experience as of a pink elephant in the room’ is an intensional context. In neither case can we infer that there exists something Vladimir is thinking about, or that there is exists something he is experiencing. This is the typical manifestation of intensionality. Anscombe regarded the error of sense-datum and naive realist theories as the failure to recognise this intensionality. (Her own example was the alleged intensionality of ‘see’, but this is controversial.)