The argument is that the rhetoric of psychology needs to be analysed in order to understand the processes of persuasion within the discipline. The work of the neurologist Karl Lashley is used to examine the ways in which a particular problem, the localization of memory, was characterized around 1950. An account is given of the holographic metaphor which was regarded as the solution to such a problem. It is suggested that such a metaphor could be regarded as a promissory note which was unfulfilled and rejected around 1980. A discussion is then given of the ways in which Lashley's work is currently being characterized. It is suggested that the assumption of modularity, or the `boxes in the brain' metaphor, could be regarded as another promissory note, and a number of the incentives offered for the acceptance of such a promise are reviewed.