A is better than B just if A has more units of goodness than B.Suppose also that better-than judgments are transitive. So, for example, if A is better than B, and B is better than C, than A is also better than C.
Given the idea of "units of goodness,' I think that these all seem like very minimal and natural assumptions. It is natural to think that we would prefer A to B if we thought that A had more of the good stuff than B.
Surprisingly, however, when we apply this schema for better-than to some actual example cases, we can derive some repugnant conclusions. Before I give an illustrative example, it helps to define goodness in some intuitively appealing way. So let's say that goodness is pleasure; we might just as well have said it was preference-satisfaction, or utility, or even human happiness so long as human happiness can be understood to be quantifiable along a single measure. (Human happiness units?) I will stick with pleasure in my example, but you could substitute 'pleasure' for anything else you like.
So now picture and compare three possible worlds to see which is better than the other:
Mass Poverty World: 1 trillion people are born and inhabit planet earth, and, over the course of their lives, they each have a total of .1 units of pleasure, a very, very small amount of pleasure for each person to have by our present standards of pleasure-expectancy.On the present schema for better than, we must say that Pig Prince World (101 billion total pleasure-units) is better than any other world. Also, we must say that Mass Poverty World (100 billion total pleasure-units) is better than Happy Medium World (99 billion total pleasure-units). But this just seems to be the wrong result! What we really want to say is that Happy Medium world is better than both of Pig Prince World and Mass Poverty World. The conclusion we are driven to is repugnant.
Happy Medium World: 1 billion people are born and inhabit planet earth, and, over the course of their lives, they each have 99 units of pleasure, a normal amount of pleasure to have by our presents standards of pleasure-expectancy.
Pig Prince World: 1 person is born and inhabits planet earth, and, over the course of his life, he has 101 billion units of pleasure, an unimaginable amount of pleasure for him to have by our present standards of pleasure-expectancy.
(These examples are my own take on a problem which goes by the name of the "Repugnant Conclusion" in the philosophical literature, and which was first articulated by Derek Parfit. Incidentally, Parfit tells a different story than I do here, and it might be debatable whether the problem I'm on about here is actually parallel to his. I think it is (we just need take Parfit's unit of goodness to be "life worth living"), but, if it isn't a parallel, then please just take the present problem in its own terms, for whatever it is worth.)
So, what has gone wrong? The assumptions we started with seemed so natural!
To solve this problem, I think that we should reject the idea that "better than" is an idea of measuring and comparing quantities of stuff. We surely don't have to understand "better than" as "greater than" for some defined unit of goodness. But then we don't have to say that Pig Prince World and Mass Poverty World are better than Happy Medium World.
However, we may still want to know why it seemed natural to us to think, initially, that more units of goodness are better than less units. The answer, roughly, is that in our actual world and in nearly possible worlds, increases in the quantity of goodness-units often enough are moral ('better-than') improvements. (And, generally, we only pay attention when they are such improvements.) The mistake is in taking this rough correlation to be an identity of the quantity and moral better-than notion; the mistake is in thinking that increases in goodness-units necessarily means improvement overall.
Just for fun, here's an alternate picture of 'better-than': 'better-than' is the idea of a kind of distance from some Ideally Perfect World--for short, let's say Heaven. A is better than B if it is closer to Heaven. A is worse than B if it is further from Heaven. A is neither better nor worse than B if A and B are, within the possibility space, equidistant from Heaven. So, we could say: Happy Medium is closer to Heaven than either Pig Prince or Mass Poverty.
I suppose I might be asked how we should measure distance from Heaven. The answer is: I'm not sure. (Nearer-my-God-to-thee units?) But also, I'm not sure it really matters to be able to say.
Metaphors aside, the deeper question really is one of how we make sense of the idea that something can be better or worse in terms of a standard or ideal. (And, incidentally, we shouldn't assume that standards couldn't be multi-faceted: an ideal pencil both holds its point and leaves an appropriately dark mark.) We want to say: surely there is something it is to think that something is better or worse in relation to a standard. What that is, I don't know. But I doubt it is going to turn out to be, at root, some measurement of a quantity of stuff.