Will MacAskill recently completed his DPhil at Oxford University and, as of October 2014 will be a Research Fellow at Emmanuel College, Cambridge.
He is the cofounder of Giving What We Can and 80,000 Hours. He’s currently writing a book, Effective Altruism, to be published by Gotham (Penguin USA) in summer 2015.
Luke Muehlhauser: In MacAskill (2014) you tackle the question of normative uncertainty:
Very often, we are unsure about what we ought to do… Sometimes, this uncertainty arises out of empirical uncertainty: we might not know to what extent non-human animals feel pain, or how much we are really able to improve the lives of distant strangers compared to our family members. But this uncertainty can also arise out of fundamental normative uncertainty: out of not knowing, for example, what moral weight the wellbeing of distant strangers has compared to the wellbeing of our family; or whether non-human animals are worthy of moral concern even given knowledge of all the facts about their biology and psychology.
…one might have expected philosophers to have devoted considerable research time to the question of how one ought to take one’s normative uncertainty into account in one’s decisions. But the issue has been largely neglected. This thesis attempts to begin to fill this gap.
In the first part of your thesis you argue that when the moral theories to which an agent assigns some credence are cardinally measurable (as opposed to ordinal-scale) and they are intertheoretically comparable, the agent should choose an action which “maximizes expected choice-worthiness” (MEC), which is akin to maximizing expected value across multiple uncertain theories of what is desirable.
I suspect that result will be intuitive to many, so let’s jump forward to where things get more interesting. You write:
Sometimes, [value] theories are merely ordinal, and, sometimes, even when theories are cardinal, choice-worthiness is not comparable between them. In either of these situations, MEC cannot be applied. In light of this problem, I propose that the correct metanormative theory is sensitive to the different sorts of information that different theories provide. In chapter 2, I consider how to take normative uncertainty into account in conditions where all theories provide merely ordinal choice-worthiness, and where choice-worthiness is noncomparable between theories, arguing in favour of the Borda Rule.
What is the Borda Rule, and why do you think it’s the best action rule under these conditions?
Will MacAskill: Re: “I suspect that result will be intuitive to many.” Maybe in your circles that’s true! Many, or even most, philosophers get off the boat way before this point. They say that there’s no sense of ‘ought’ according to which what one ought to do takes normative uncertainty into account. I’m glad that I don’t have to defend that for you, though, as I think it’s perfectly obvious that the ‘no ought’ position is silly.
As for the Borda Rule: the Borda Rule is a type of voting system, which works as follows. For each theory, an option’s Borda Score is equal to the number of options that rank lower in the theory’s choice-worthiness ordering than that option. An option’s Credence-Weighted Borda Score is equal to the sum, across all theories, of the decision-maker’s credence in the theory multiplied by the Borda Score of the option, on that theory.
So, for example, suppose I have 80% credence in Kantianism and 20% credence in Contractualism. (Suppose I’ve had some very misleading evidence….) Kantianism says that option A is the best option, then option B, then option C. Contractualism says that option C is the best option, then option B, then option A.
The Borda scores, on Kantianism, are:
A = 2
B = 1
C = 0
The Borda scores, on Contractualism, are:
A = 0
B = 1
C = 2
Each option’s Credence-Weighted Borda Score is:
A = 0.8*2 + 0.2*0 = 1.6
B = 0.8*1 + 0.2*1 = 1
C = 0.8*0 + 0.2*2 = 0.4
So, in this case, the Borda Rule would say that A is the most appropriate option, followed by B, and then C.
The reason we need to use some sort of voting system is because I’m considering, at this point, only ordinal theories: theories that tell you that it’s better to choose A over B (alt: that “A is more choice-worthy than B”), but won’t tell you how much more choice-worthy A is than B. So, in these conditions, we have to have a theory of how to take normative uncertainty into account that’s sensitive only to each theory’s choice-worthiness ordering (as well as the degree of credence in each theory), because the theories I’m considering don’t give you anything more than an ordering.
The key reason why I think the Borda Rule is better than any other voting system is that it satisfies a condition I call Updating Consistency. The idea is that increasing your credence in some particular theory T1 shouldn’t make the appropriateness ordering (that is, the ordering of options in terms of what-you-ought-to-do-under-normative-uncertainty) worse by the lights of T1.
This condition seems to me to be very plausible indeed. But, surprisingly, very few voting systems satisfy that property, and those others that do have other problems.
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