In the middle of a conference on the logic of science, an eminent biologist once said: "Does it not bother you guys that we scientists do not use any logic at all." This statement was meant to be a friendly provocation, but there also was a serious message. Scientists often say that the logical analyses are exercises in formal logic and fail to illuminate what the scientists are doing, actual scientific practice. This recurring complaint, although not completely as I will suggest, has not gone unnoticed in the philosophy of science. Indeed, the current trend in analytic philosophy of science as well as in teaching the method of science (if there is such an animal) has been away from (formal) logic as a means of illuminating scientific inquiry.¹