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| title | date | techne | episteme |
|---|---|---|---|
| Utilitarianism Without Trade-Offs | 2012-05-27 | :wip | :speculation |
The cost of something is what you give up to get it.
-- Second Principle of Economics, Mankiw
A common criticism of utilitarianism denies the plausibility that utility can be meaningfully aggregated, even in one person and under (near-)certainty. Let's say I offer you two choices:
- I give you two small things, one good, one bad, of exactly opposite value. (Say, a chocolate bar and a slap in the face.)
- I give you two large things, one good, one bad, of exactly opposite value. (Say, LSD and fever for a day.)
The sum of utility for each choice is exactly 0, by construction1, and therefore, you should be indifferent between them.
This is assumed to be absurd, and therefore utilitarianism is false.
But where exactly does it fail? A chocolate bar is good, that's fact. Let's not focus on whether you may not like chocolate, or can't digest it, or whatever - substitute a different snack. And also ignore whether a snack is morally good, like that's a grave and serious problem, and chocolate is only about preferences, not The Good. Whatever, don't get hung up on the word. A chocolate still feels good, and let's keep it at that. Just a simple observation.
And there are things that are more good in that sense. Cake is better. As is [Runner's High][]. Or the Fifth Season of Mad Men. You get the idea. So some things are good, and they can be compared. Maybe not at a very fine-grained level, but there are at least major categories.
There are also bad things. And they, too, can be compared. Some things are worse than others.
So we could rephrase the original choice without any explicit sum. First, I observe that you have two preferences:
- You prefer the large good thing over the small good thing.
- You prefer the small bad thing over the large bad thing.
Those two preferences have a strength. There might not be an explicit numerical value to it, but we can roughly figure it out. For example, I could ask you how much money you'd be willing to pay to satisfy each of those preferences, i.e. how much you'd pay to upgrade your small good thing to a large one2, and similarly downgrade the bad thing.
Then I tweak the individual things until both preferences feel equally strong. And this seems now far less absurd - if you knew I was going to give you a chocolate bar and make you sick a week later, and I offered you the choice between either upgrading to LSD or downgrading to a slap in the face, then, I think, being really uncertain seems very plausible to me.
You might be willing to flip a coin, even.
Alright, so rankings and indifference between choices seem plausible, so why does the original scenario fall apart?
Because it puts good and bad things on the same scale. It treats bad things as anti-good things, the same way money works. "Pay 5 bucks, gain 5 bucks" and "pay 5 million, gain 5 million" are, everything else being equal, really the same deal in disguise.
Good and bad things are on different scales. There is one non-negative scale for good things, and one non-negative scale for bad things, and they are fundamentally orthogonal. A choice can be simultaneously good and bad, without one cancelling out the other.
So recall the second scenario, the one in which we might be willing to flip a coin. Try to actually feel that uncertainty. If you're anything like me, it feels very different than the uncertainty you might feel when you can't decide which red wine to buy. It's not a "meh, whatever" kind of indifference - it's "this completely sucks and I wish I wouldn't have to make this decision at all".