Gerd Gigerenzer's views on probabilistic reasoning in humans have come under close scrutiny. Very little attention, however, has been paid to the evolutionary component of his argument. According to Gigerenzer, reasoning about probabilities as frequencies is so common today because it was favored by natural selection in the past. This paper presents a critical examination of this argument. It will show first, that, pace Gigerenzer, there are some reasons to believe that using the frequency format was not more adaptive than using the standard (percentage) format and, second, that Gigerenzer's evolutionary argument and his other arguments such as his historical description of the notion of probability are in tension with each other.
2008 The Philosophy of Science Society, Japan