Saturday, January 30, 2010

Oppy on Moral Arguments (Part 9): The Argument from Convergence

This post is part of my series on Graham Oppy's discussion of moral arguments. For an index, see here.

The Argument Stated
The ninth argument covered by Oppy is a neglected historical oddity. It is attributed to Henry Sidgwick (who did not endorse it) and is known as the argument from convergence. Take a look:
  • (P1) What I have most reason to do is what will best secure my own happiness.
  • (P2) What I have most reason to do is what morality requires.
  • (P3) If there is no moral government of the universe, then what will best secure my happiness is not always what morality requires.
  • (C1) Therefore, there is a moral government of the universe.
  • (C2) Therefore, there is an orthodoxly conceived monotheistic god.
This is actually a pretty profound argument, and more deserving of consideration than the tawdry argument from the need for justice (which is similar in content). I think it neatly summarises certain opinions and intuitions that we have about the nature of morality. In particular, it captures the tension that most people see between self-interest and morality.  

Anyway, there is no need to wax lyrical on it for too long, we need to know whether the argument is successful.

Sidgwick rejected the conclusion of this argument for one simple reason: he thought it more likely that there was a fundamental irreconcilable tension in the faculty of practical reason, than that there was a God to reconcile them. I tend to agree.

Oppy notes, as I did a moment ago, that the argument equivocates between prudential reason and moral reason. One way to resolve the tension is to reduce moral reasons to prudential reasons or vice versa. Many secular theories of morality do this. For example, Hobbes reduced moral reasons to prudential reasons of a particular sort.


  1. I don't understand Sidjwick's reasoning. What does tension has to do with anything? Is Sidjwick denying both P1 and P2, in the sense that there is no one thing that "I have most reason to do"?

    I note that one can escape the argument via other means:

    A) Embracing P1 but denying P2 (so we are driven by happiness, not morality); I don't think that's a problematic solution, as many would say man is an immoral beast.

    B) Denying P2 but embracing P1 (so we ultimately seek to do what is right, not what is moral); again, a plausible solution, since many would say deep down we want to do good.

    I do agree with P1, as a psychological truth (although the phrasing is a bit tricky), and P2 is an excellent definition so I accept it too (but one should not confuse it with all meanings of the "morality" word).

    I'd note that embracing both P1 and P2 leads to individualistic subjectivism (what will best secure my happiness IS what morality requires), so that P3 doesn't really make sense in light of the prior assumptions (no world governance is going to make what secures my happiness something other than what secures my happiness). P3 makes no sense without equivocation between moral reason ("what morality requires") and objective morality (a meaning for "what morality requires" which allows it to be different from "what will best secure my happiness"); of course that stands in contradiction to (P1 & P2), so the argument is fallacious.

  2. B should read:

    B) Denying P1 but embracing P2 (so we ultimately seek to do what is right, not what feels good); again, a plausible solution, since many would say deep down we want to do good.

  3. Yair,

    I'm not an expert on The Method of Ethics, but I'm pretty sure that the argument derives from Sidgwick's struggle to offer a good argument for his preferred brand of utilitarianism (he had a common good variety of utilitarianism in mind). He preferred utilitarianism to egoism, but accepted that egoism was equally rational.

    So, in Sidgwick's ideal world we would all be common good utilitarians, but from what he could observe we had good reason to be egoistic.

    He wasn't denying P1 and P2, he was accepting them both, but thought it would be great if there was some way to accept only P2.

    I agree with everything else you said. I was thinking of something similar to individual subjectivism when I say you could reduce moral reasons to prudential reasons. Perhaps what I said wasn't very clear since the original argument was about a conflict between happiness and moral reason.