ABSTRACT

The topic of scientific discovery presents us with a paradox. There are powerful skeptical arguments from logic, philosophy of science, historiography, and sociology of science against the very possibility of logics of discovery, and indeed of a general scientific method. Yet Bacon, Descartes, Newton, Leibniz, and other proponents of discovery methods would be delighted could they tour today’s scientific facilities. Bacon and the other founders of modern science – concerned that discovery had hitherto been sporadic and accidental, a product of luck rather than logic – attempted to provide general methods that would “level wits” and enable natural philosophers to engage in a systematic enterprise guaranteed to generate new knowledge. In their view the received logics and rhetorics of their day were sterile techniques for arranging what was already known. In Why Was the Logic of Discovery Abandoned? Larry Laudan (1981: Ch. 11) noted that discovery was important to these investigators not only as a way to produce new knowledge but as a way to produce new knowledge. The discovery path was epistemologically relevant primarily because a reliable path to a conclusion is the strongest form of justification, in empirical science as in logical proof. This is a generativist view of justification. But by the turn of the nineteenth century, the method of hypothesis was increasingly touted as a legitimate and more flexible way to investigate nature and to communicate final results. In theoretically deep domains at the frontier of research, it is difficult or impossible to accumulate enough observational information to draw interesting inductive conclusions or to create new theoretical vocabularies. By contrast, an hypothesis can often be tested against a scattering of observational information, and the hypothesis guides research in telling us precisely what to look for. For those and other reasons, generative methods gradually gave way to consequentialist methods in the maturing sciences, and methodologists detached final justification from discovery. Consequentialism’s premise is that it does not matter how we hit upon our hypotheses, only how they are tested, the test predictions being logical consequences of the hypotheses. Tested, not proved (because of the fallacy of affirming the consequent), but natural philosophers were already coming to realize that certainty

is impossible to attain, that science is better regarded as an ongoing, multi-pass, selfcorrecting enterprise in which scientists cycle back to refine previous results, investing them with greater theoretical and experimental richness. During this period, then, we find a logical inversion in methodology, from generativism to consequentialism. The method of hypothesis, once an heuristic crutch to be thrown away when full inductions were achieved, now became the official method of science; and inductive methods were demoted to the Baconian, historical sciences. Since then, discovery methods have been associated with the data-driven, correlational sciences rather than with deep theoretical work. During the twentieth century the logical empiricists and the Popperians, who made philosophy of science a professional, academic subject, institutionalized the consequentialist turn. Hans Reichenbach’s 1938 distinction of context of justification from context of discovery eventually became a powerful criterion to demarcate the universal, normative, internalist, epistemological concern of philosophers with the “final products” of research from the supposedly particularist, externalist concern of historians and psychologists merely to describe the process of investigation. The most familiar statement of the two-context distinction is found in karl Popper’s Logic of Scientific Discovery, which portrays theories in an Einsteinean manner as “free creations of the human imagination.” Thus discovery issues came to be ruled out-ofbounds as an epistemological topic until a revival of interest began around 1960. A major objection, anticipated by Charles Peirce in his work on economy of research, but soon forgotten, is that discovery path must be coupled to justification in the minimal sense that, unless some of the theory candidates to be tested have a chance of being truthful or fruitful, hypotheticalism has no chance at all of realizing its stated goal. Interestingly, in his own work, Reichenbach bucked the strong consequentialism that inspired the two-context distinction, for he retained a generativist methodology of induction as epitomized by his straight rule: if m results in n trials produce outcome O, to infer that m/n of all cases are O. The rule is to be applied repeatedly, in a selfcorrecting manner, with a hoped-for long-run convergence on the correct result. And in his study of probabilistic causal relations, in which one cause can screen off others (a topic fruitfully developed by his student Wesley Salmon), Reichenbach anticipated the causal network approach described under “Some reasons for optimism,” below.