Full Idea
The chief difficulty with the behaviour-disposition account is the virtual impossibility of specifying a disposition except as a 'disposition of x to behave as though x were in pain'.
Gist of Idea
Dispositions need mental terms to define them
Source
Hilary Putnam (The Nature of Mental States [1968], p.57)
Book Reference
'The Philosophy of Mind', ed/tr. Beakley,B /Ludlow P [MIT 1992], p.57
A Reaction
This has become the best-known objection to behaviourism - that you can't specify a piece of behaviour clearly unless you mention the mental state which it is expressing. The defence is to go on endlessly mentioning further behaviour.