Contending that the quest for a logic of scientific discovery was prematurely abandoned, the author lays down eight phenomena that such a logic or theory must explain: the banality of scientific discovery; the trainability of scientists; the high incidence of simultaneous discoveries; the ubiquity of relative novices; the fact of scientific genius; the barrenness of isolated workers; the incommensurability of concepts of successive theories; and the quasi-incorporation of old concepts, objects, and methods in successor theories, The author then presents a new theory or logic of discovery according to which discoveries are the termini of "tweak paths" generated when scientists "tinker" with the laws, concepts, methods, and instruments of a given theory. Tinkering and tweaking are illustrated by examples from many-valued and modal logic and from Darwinian biology. Through the history of planetary discovery, the accidental role played by luck or good fortune in some discoveries is explored, but the author emphasizes that in a deep sense serendipity is an in eliminable feature of all scientific discovery because scientists never know m advance whether their tweaks will lead to dead ends or to positive developments. The author's new theory of scientific discovery is shown to account for all eight explananda, ft also reveals science to be a more egalitarian enterprise than the traditional view of scientific discovery as ultimately inexplicable depicts it.
