It is clear now that these models will not suffice. It will be argued below that there are a number of strands of research into 'ordinary' motivation which cannot be explained without using 'mental' terms such as belief or insight.
Researchers often talk about the 'reinforcing' or 'rewarding' effects of smoking and drinking.
In talking in this way about human behaviour they are clearly invoking the tradition of research in psychology known as behaviourism, although contemporary non-behaviourist animal learning theory employs the same terms in the same ways. Behaviourism in its most well-known forms insists that all that need be explained is an organism's behaviour, that since we have no way of looking into a rat's mind all that can be researched is the behaviour, and thus psychology must restrict itself to terms and constructs which are definable in terms of externally observable behaviour. Even instances of human behaviour which seem to be reports of internal, mental events are best looked at in the same way, as instances of externally observed behaviours. This is appealingly rigorous and scientific, and if successful does away with all sorts of philosophical knotty problems such as the mind-body dilemma by abolishing the mental realm entirely. It seems to me that its physicalism is what is most appealing about behaviourism.