CONTRASTING MCMULLIN(S) VISION WITH RIVAL EPISTEMOLOGIES
McMullin does enough to discredit some alternative projects with a similar aim, such as attempts to define induction as a method for science. Today other projects of that sort exist as well, drawing in one way or another on the concept and theories of probability, notably varieties of Bayesianism or a more liberal probabilism. It would be of interest to ask how, or to what extent, such alternatives could do justice to the insights that support McMullin’s concept of retroduction as the crucial or central form of scientific inference. I will leave that aside as well. The more interesting question, for me, is rather whether scientific practice, the enterprise of science, is best characterized in that sort of form at all.
McMullin does not have an overriding ambition in this project. He emphasizes that it was “not intended to furnish a criterion of demarcation between science and non science [ . . . .] retroductive inference makes use of ingredients that are commonplace in human reason generally” (144). In good human reasoning to be sure; McMullin mentions approvingly the detective and the journalist. But retroduction is easily discerned in not so good human reasoning as well, when conspiracy theorists are retroductively inferring from the facts in evidence to their weird or wonderful causal explanation. So it seems at least at first blush as if the hallmark of scientific inquiry will not be that the form of inference is different, but rather how well it is employed:
What is distinctive about the way in which explanatory theories are constructed and tested in natural science is the precision, as well as the explicitness, with which retroductive inference is deployed. (146)
But that is too modest. It is not just a matter of doing it better, not just a matter of greater precision and explicitness, because McMullin emphasized features of the practice that are not captured by such earlier accounts as
Bas C. van Fraassen 133
were focused on deduction, induction, or even Peircean abduction. The details emerge for McMullin after a long scrutiny of errors and insights accumulating through some twenty centuries of reflection on the matter, and they are not simple or neat, let alone algorithmic.
As a process of inference, retroduction “is not rule-governed as deduction is, nor regulated by technique as induction is” (183). McMullin elaborates on this elsewhere, indicating a strong difference from another rival that was much in the limelight in the closing decades of the twentieth century:
retroduction [ . . . ] is not a strict form of rule-governed reasoning, or at least, it is not as long as it isn’t equated with the easily-criticized “inference to best explanation.” [ . . . .] The vulnerability of such an inference need hardly be emphasized. (McMullin 2007, 175)
These are important differences, and it is a characteristically twentieth- century insight that rational change in view is not a matter of rule following, that rules of right reason cannot be dictates, only guidelines. But something is needed beyond this negative point.