Intellectual diversity — difference — has long been used in human affairs to minimise the impact of mistakes. In the past couple of decades design diversity has been used to seek dependability in software-based systems. This use of design diversity prompted the first formal studies of the efficacy of intellectual diversity. In this paper we examine diverse arguments — in particular arguments to support claims about system dependability (reliability, safety). Our purpose is to see whether the probabilistic approach that has been so successful in design diversity can be applied to diversity in arguments. The work reported here is somewhat tentative and speculative.