This study sought to identify the extent to which claims about the probable characteristics of offenders in 'offender profiles' were based on substantive arguments. Because Toulmin's (1958) philosophy of argument has been demonstrated as a useful way of breaking down arguments into their constituent parts (Burleson, 1979) we examined the extent to which profiles contained grounds, warrants, backing and rebuttals to support or refute various claims about offenders. Twenty-one profiles, representing a range of 'profiling styles', were obtained from a variety of sources. All of these had been used in major criminal investigations either in the UK or internationally. Of the nearly 4,000 claims made, nearly 80% were unsubstantiated. That is, they contained no grounds, warrant, backing or rebuttal. Moreover, less than 31% of the claims were falsifiable. We argue that (a) this demonstrates the need for a careful, systematic evaluation of profiling advice (b) Toulmin's structure is one useful method for evaluating such material and for providing a possible framework for such advice.

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