The third-way third wave and the enduring appeal of bioexceptionalism.

We may induce from a longue durée examination of Anglo-American History of Biology that the impulse to reject reduc - tionism persists and will continue to percolate cyclically. This impulse I deem "bioexceptionalism": an intuition, stance, attitude, or activating metaphor that the study of living beings requires explanations in addition to exclusively bottom-up causal explanations and the research programs constructed upon that bottom-up philosophical foundation by non-organismal biologists, biochemists, and biophysicists - the explanations, in other words, that Wadding - ton (1977) humorously termed the "Conventional Wisdom of the Dominant Group, or cowdung." Bioexceptionalism might indicate an ontological assertion, like vitalism. Yet most often in the last century, it has been defined by a variety of methodological or even sociological positions. On three occasions in the interval from the late nineteenth century to the present, a small but significant group of practicing biologists and allies in other research disciplines in the UK and US adopted a species of bioexceptionalism, rejecting the dominant explanatory philosophy of reductionistic mechanism. Yet they also rejected the vitalist alternative. We can refer to their subset of bioexceptionalism as a "Third-Way" approach, though participants at the time called it by a variety of names, including "organicism." Today's appeals to a Third-Way are but the latest eruption of this older dissensus and retain at least heuristic value apart from any explanatory success.