Darwin the Philosopher

I have noted several unfortunate statements by scientists, some of whom I deeply respect, expressing disdain for philosophy. Their view, apparently, is that if you have science you have no need for philosophy. This attitude is doubly unfortunate. First, it betrays considerable ignorance, and, second, when scientists reject philosophy, they really, really should avoid philosophical questions, like the existence of God, because they say embarrassing things that a bit of philosophical insight would have spared them.

Really, though, scientists themselves often resort to arguments that are philosophical in nature. Here is an imagined exchange I saw recently (maybe here at Secular Outpost) that bears repeating:

Scientist: What is the point of philosophy?

Philosopher: What is the point of science?

Scientist: Well, the point of science is…

Philosopher: …And you are now doing philosophy!

I think this little dialogue nails it, but it might help to note a more extended example of an outstanding scientist who also employed philosophical arguments in one of the most famous of all works of science. Here is an extended quote from Chapter Seven of my book It Started with Copernicus, Prometheus Books, 2014:

In The Origin of Species, Darwin frequently addresses philosophical as well as scientific questions. For instance, as we noted in Chapter Two, he devotes considerable space to examining the hypothesis of special creation as a theory competing with natural selection. He realizes that special creation is, of course, more than just a purportedly scientific claim, and impinges on deep philosophical and religious commitments. In addressing special creation, therefore, Darwin often speaks the language of philosophy and even theology. Darwin’s remarkably comprehensive intellect, his background that encompassed both theology and natural science, and his sensitivity to cultural context, made him a particularly qualified commentator on the relation between science and religion.

Darwin addresses the nature of design hypotheses, showing why they are perennially problematic within science. By noting numerous examples, Darwin shows that design arguments raise particular problems for scientific explanation. It is not simply that natural selection provides a physical modus operandi and design hypotheses do not. Darwin does not beg the question in favor of materialism. Rather, as Darwin repeatedly shows, design hypotheses are so exiguous in content that they fail in the most basic task of scientific explanation, viz., providing some new piece of information that tells us why the phenomenon was to be expected.

On the other hand, if design hypotheses are given content, as by invoking a benevolent creator, then they raise the perennially thorny problem of how natural evil can be reconciled with the existence of a provident creator. Darwin would sometimes play the role of “Devil’s chaplain” by noting some natural facts that seem to us particularly horrifying or repugnant, like wasps that lay their eggs in the paralyzed, but living, bodies of caterpillars, so that the wasp larvae can slowly devour them from inside. Darwin notes that such survival strategies are expected if living things evolved by an unthinking, unplanned, amoral process like natural selection. However, they are deeply problematic if we see all of nature as the product of an intelligent and benevolent creator. Another problem with intelligent design hypotheses is that many alleged designs look unintelligent. Organisms often solve problems with anatomical or behavioral features that do the job, but hardly with ideal efficiency. This is understandable if such features are the result of a blind watchmaker—natural selection—but hard to explain as a product of a creator with superhuman intelligence and power. When some replied that God might have a good reason for permitting such apparent instances of bad design, Darwin replied that if we hypothesize that God planned things, but then the “plan” we allege looks no different from no plan at all, then the hypothesis is vacuous. This is an astute philosophical observation.

Philosophical differences also divided Darwin from some of his scientific critics such as Richard Owen. As noted in Chapter Two, Owen coined the term “homology” to designate deep structural similarities in anatomical features that are superficially very different. A bat’s wing, a human hand, a bear’s paw, and the flipper of a porpoise look very different and have very different uses. However, when we look at the underlying skeletal structure, we see that these structures match very closely. Darwin adduced homologies as strong evidence for evolution. Shared structure is evidence of descent with modification from a common ancestor. Owen, however, was a biological Platonist who held that individual organisms reflect an ideal archetype. Hence, for Owen, homologies are not evidence of a common ancestry, but show that many different species have been created according to the same plan.

The difference between Darwin and Owen on homologies therefore could not be settled by a straightforward appeal to evidence. Each recognized the evidence but claimed it for his theory. The fundamental difference between Owen and Darwin was not scientific but philosophical and chiefly concerned the kind of explanations that should be invoked by scientific theories. Like practically all current scientists, Darwin was committed to the sort of methodological naturalism discussed in Chapter Three. Only physical causes are admissible in scientific explanations, and appeal to transcendent objects, like archetypes was ruled out. Again, what constitutes an acceptable scientific explanation is not a scientific but a philosophical question.

In cases like this, where the evidence will not settle the dispute, scientists must employ philosophical arguments. And they do. Therefore, the suggestion that science can simply replace philosophy is wrong for the reason that, as [Thomas] Kuhn observed, scientific debates often embed—or are embedded within—philosophical debates. These philosophical differences often cannot be settled by straightforward empirical means, but must be addressed with philosophical argument. Science cannot replace philosophy because philosophy is an essential part of the scientific enterprise. Kuhn was wrong about many things, but on this point he was absolutely right.