Behavioral Consistency, the Homology Assumption, and the Problems of Induction

The ultimate goal of profiling is to identify the major behavioral and personality characteristics to narrow the suspect pool. Inferences about offender characteristics can be accomplished deductively, based on the analysis of discrete offender behaviors established within a particular case. They can also be accomplished inductively, involving prediction based on abstract offender averages from group data (these methods and the logic on which they are based is detailed extensively in Chapters 2 and 4). As discussed, these two approaches are by no means equal. The reliability and validity of inductive profiling rest almost exclusively on two weak theories: behavioral consistency and the homology assumption. Behavioral consistency posits that the same offender will do the same thing across the span of time during different offenses. The homology assumption suggests that, generally, there will be a similarity between different offenders who commit similar crimes. Without either of these theories, comparing the current offender(s) to past offenders is essentially futile.