About Rationally Speaking
Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.
Tuesday, October 11, 2011
New 5-minute Philosopher video: reflective equilibrium
we are going to take a look at one of the fundamental tools of the philosophical toolbox, something called reflective equilibrium.
Let’s suppose that you believe in the inerrancy of the Bible. Suppose you also think morality comes from God. And further suppose that you maintain that it is immoral to kill children if they curse their parents. Then you read the following in Exodus 21:17: “He that curseth his father, or his mother, shall surely be put to death.”
Now, if you are concerned about the coherence of your beliefs, you have several moves at your disposal. You could admit that the Bible is not infallible, and that God may not have meant what Exodus attributes to Him. Or, you could abandon the idea that morality comes from God. Lastly, you could agree that yes, after all it is all right to kill children who disrespect their elders. In considering any of these options, and actually adjusting your set of beliefs about morality, divinity and children’s behavior, you have engaged in an exercise of “reflective equilibrium.”
The idea of reflective equilibrium was introduced by Nelson Goodman in his book “Fact, Fiction, and Forecast.” Goodman was not concerned with morality, but with the validity of one’s thinking. Goodman’s suggestion was that we justify our rules of reasoning based on how those rules fare when confronted with a range of instances of what we believe are correct inferences. If an inferential rule yields unacceptable results, we may decided to discard that rule no matter how it may have seemed like a good idea at the start.
The most famous application of the principle of reflective equilibrium is found in John Rawls’ highly influential “A Theory of Justice.” Rawls proposed to apply Goodman’s approach to adjusting our sometimes conflicting moral beliefs, just as in the hypothetical case of the Bible and disrespectful children mentioned before. Whether or not one agrees with the outcome of Rawls’ particular analysis of justice as fairness, the reflective equilibrium approach should be compelling to anyone seriously interested in, well, reflecting on her own beliefs.
Turns out that a similar approach had been used in philosophy of science by Pierre Duhem as a way to debunk the commonplace idea that science is about direct empirical testing of theories. Duhem, in a book published in 1908 (La Théorie Physique), pointed out that if there is a disagreement between a theory and the empirical evidence one cannot automatically reject the theory, because scientific theories are complex statements that include many assumptions and sub-theories. The existence of a disagreement between theory and evidence tells us that something is wrong, but not what. It could be that the core theory — say, the Copernican system — ought to be rejected. But it could also be that some adjustment to the theory would resolve the discrepancy (for example, Kepler’s modification of the original Copernicanism to account for the fact that the planets go around following elliptical, not circular orbits). Indeed, it may even be the case that the data is wrong, because of a malfunction of the instrumentation, or an error of interpretation.
The 20th century philosopher W.V.O. Quine extended Duhem’s thesis, arguing that whenever there is a discrepancy in our understanding of the world, one could potentially change any of all the interconnected statements that constitute our web of knowledge to account for the discrepancy. Famously, Quine held that even logic itself may have to be altered if it turned out that there were enough problems caused by its application, all of it done through continuous rounds of reflective equilibrium.
The idea of reflective equilibrium is therefore one of the most powerful in philosophy, as it embodies a quintessentially philosophical approach to problems of all kinds. It is also applicable in everyday life, of course, and can be used to introduce everyone to what it means to think philosophically. The crucial thing to remember is that the equilibrium is not meant to be static: new evidence and new ideas constantly enter the system, and a wise person keeps adjusting her beliefs accordingly. Try it, it’s a refreshingly liberating exercise.