Thursday, October 02, 2008

Random philosophy note

I'm not well-read in philosophy, but I'd like to point out one point of view I find particularly strange: the idea that we can derive a system of ethics from science and logic alone.

Readers of this blog might be a little surprised -- aren't I a mathy, nerdy kind of guy? Indeed, and this is precisely the reason why I consider the "all ethics can be derived from science" position to be so bizarre. After all, anyone familiar with abstract mathematics knows that our choice of axioms -- our set of starting assumptions -- is critical. A seemingly innocent assumption, such as the Axiom of Choice, can have wildly unintuitive consequences, like the Banach-Tarski paradox and a well-order of the real numbers. Under the classical set theory axioms, a basic question like the Continuum Hypothesis is provably irresolvable. You can't get anywhere in formal mathematics until you have a very clear set of starting axioms. You have to make some basic choices about the structure of mathematics before you can make any logical derivations, and these choices matter. 

It's the same with morality. First, you have to set down some basic axioms, and this process will inevitably involve subjective human judgment. Perhaps you think you can circumvent this by calling upon evolutionary biology or some other science, but even then you're axiomatizing the assumption that evolutionary biology should matter in moral philosophy, which is hardly a core logical principle. After you choose your axioms for moral evaluation, of course, then you should use science and logic to draw normative inferences, but you can't claim that you "started" with basic logic. That just doesn't make any sense.


Matt Zeitlin said...

Besides Randians, is there really anyone else who derives an entire ethical code from "logic and science" alone? I mean, there's obvious a continuum (with strict duty based folk and the hard core utilitarians on one side and the pragmatists on the other), but I'm pretty sure the even most on the hardcore side admit that their starting axioms are basically intuitive (pain is bad, truth is good, stuff like that)

fortruth said...

There is a big difference between axioms in math and axioms in philosophy. An axiom in math is the starting point that defines the basic structure of some hypothetical system. Therefore it can neither be proved nor be disproved.
Philosophy deals with the real world. An axiom in philosophy is a principle that is implicit in every thought. It cannot be proved, true, but it does not need to be proved. By it's very nature, it is impossible to conceive of it not being true. "I am conscious" is an axiom. Are you claiming this inevitably involves subjective human judgement? Suppose that is true. But to make a judgement (subjective or not) I have to be conscious. See?

Matt Rognlie said...

To fortruth:

There is also a big difference between axioms in ethics and the axioms you mention. I agree that there are some principles, like "I am conscious," that are so necessary to think coherently about the world that it is reasonable to rely upon them as axioms. I do not see how even a generous enumeration of such axioms can come close to providing us with a system of moral philosophy.

Hacks using rhetorical slights-of-hand may try to bridge this gap. For instance, they might say, if consciousness is an axiom necessary for all rational thought, then a system of rational thought must recognize that intelligent consciousness should generally be preserved. This "deduction" might lead them to make all sorts of ethical conclusions about the importance and nature of human life. But even this doesn't really make sense: there is nothing internally inconsistent about wanting your existence to end, or wishing that you never existed in at all, even when that existence is necessary to have such thoughts in the first place.