How to arrive at conclusions: Darwin, Bacon, Mill, and the Philosophy of Science

I wish I'd had a little more Philosophy of Science early in my educational career. I might have benefited from a straightforward introduction to Aristotle, Francis Bacon, and John Stuart Mill. In college I was exposed to these people, generally in the forbidding context of analytic philosophy. I tried to penetrate their books, and dutifully took notes during the professor's lectures, but despite the best efforts of several Cornell University philosophy and comparative literature professors I didn't take away much of anything at the time. It might have been better to have engaged these schools of thoughts for their contributions to thinking at a somewhat non-technical level, that is, at the level of how people reason and what constitutes valid arguments.

There are a million opinions out there, about everything from the war in Iraq to whether Atkins works or doesn't work. And commentators frequently resort to bizarre, unnameable rhetorical backflips to explain their views. How to sort it out? How has the landscape of ideas become so messy? Relativists try and make the case that there is more than one way of reasoning, so "we could both be right." But they are wrong.

Also annoying are the attempts to culturalize rationality. These are particularly unhelpful when dealing with the Hindu right in India or radical Islam in the Arab world. It is not a sell-out to colonialism to claim that reason is universal.

In fact there is more than one way of reasoning, but that doesn't mean everyone can have his or her own private rationality. Really there are still two -- and only two -- generally acceptable forms of rationality, inductive and deductive reasoning. Inductive reasoning derives generalities from specific observations, while deductive reason begins with generalities and derives specific conclusions. Deductive reasoning is associated with Aristotle, whereas inductive reasoning (the foundation for the methodology of hard science) was conceived by Francis Bacon (also see this helpful site for context. It's aimed at high schoolers, but I learned a thing or two from it!). Most scientific research follows the inductive path, but forms of deductive reasoning are still used in mathematics as well as in fields like particle physics.

Fine, but what happens when you have complex theories like evolution? When Darwin published The Origin of Species, two of the dominant philosophers of science of the Victorian era, John Stuart Mill and William Whewell, attacked him for using what they perceived as deductive reasoning. Evolution, one realizes, will never be empirically verifiable using direct observation, because it would take thousands of years to verify even the simplest evolutionary advances. (The impossibility of direct observation keeps creationists going, year after year.) But Darwin's theory of evolution, while it remains technically a theory, is based on a form of inductive reasoning nonetheless, only a very specific kind: inference.

See this review of David Hull's new book Darwin and His Critics in the Skeptical Inquirer.

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