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Day March 3, 2005

Book #9: What Makes Biology Unique? by Ernst Mayr

Following the death of Ernst Mayr last month, I decided to read his last book, What Makes Biology Unique? The book consists of a set of essays arranged to form a coherent look at what makes biology different from the physical sciences Unfortunately, if you’ve read Mayr’s previous works, and in particular Toward a New Philosophy of Biology, little in this most recent collection will be new material.

For me, the gems of this most recent collection were chapters 3 and 4, on teleology and the difference between analysis and reductionism, respectively. In many ways, these two chapter illustrate problems within biological explanation, albeit problems which are polar opposites. Teleology, in particular, does not receive enough attention. Working biologists today rarely succumb to finalist arguments that particular structures are “goal directed,” but the entire “Intelligent Design” movement is an attempt to reintroduce finalism or what Mayr calls “cosmic teleology” to the explanation of biological origins. Mayr demolishes finalism by analyzing the five senses in which teleology can manifest in biological explanation, and shows how entirely legitimate notions such as teleonomy (the expression of a stored purposive program, such as DNA/development) can easily be mistaken for the ontological idea that there is an inherent “goal” or “direction” to evolution. From such a belief, it is a short distance indeed to the notion that such a direction must be given by a “designer” who guides the overall process. In moving from teleonomy to cosmic teleology, and thence to the need for a designer, we move from the realm of falsifiable science to speculation and faith. One of Darwin’s greatest gifts, reinforced by Mayr and others, is confidence that the world need not have an overall “direction” or “purpose” for it to be explainable and comprehensible.

Chapter four reminds us of the opposite problem: that taking things apart into smaller pieces (analysis) can, and often does, get mistaken for the ontological position that explanation is only found by theorizing about the smallest scale entities we can know. The latter position, reductionism, is rampant in post-Cartesian science. Chemistry is explained only by reducing it to physics, and macroscopic physics is explicable only in light of particle physics and quantum theory. In biology, reductionism has been abetted by the spectacular success of molecular methods, which would seem to suggest that “real” explanations in biology must be biochemical and molecular. Mayr reminds us that we must not confuse the method — analysis — with reductionism, which is more akin to a faith. Each science, and in particular biology, is rife with “emergent” properties which arise through the novel organization of smaller parts, and cannot be simply reduced to a description of the smaller parts. Ultimately, emergence is what necessitates an autonomous biology, one that cannot be simply reduced to an interestingly complex branch of chemistry or biophysics — but one that can utilize and leverage analysis at smaller scales when appropriate.