Logic of the Greatest Happiness Principle
Peter Geach has a weird criticism of Bentham’s utilitarianism in his book The Virtues. He objects to having “the greatest happiness for the greatest number” as the ultimate moral aim.
His problem is not with the difficulty of measuring happiness, or comparing the happiness of one person with that of another. Rather, he claims, there is a logical problem with the principle.
I admit to not quite understanding what the logical problem is meant to be. Geach cites Fowler’s Modern English Usage as his authority (he praises Fowler as somebody untrained in formal logic but with exceptional logical instincts).
In a section called “illogicalities” Fowler discusses the sentence “Never were finer lines perverted to a meaner use”. We know well, says Fowler, what the author of this sentence is trying to do — to emphasise the meanness of the use. But the use of two implicit superlatives weakens rather than strengthening the second. It would have been more powerful, given the author’s intention, to have written: “Never were fine lines perverted to a meaner use”.
It is easy to understand what Fowler means. The finest lines are a subset of the fine lines, and fine lines are a subset of all the lines (Figure 1). So the meanest use to which the finest lines are put might well be less mean than the meanest use to which fine lines are put — the sample size is likely smaller — and less mean again than the use to which lines in general are put. If you want to say that the use is very mean, you do best to say that it is the meanest to which lines in general have been put.
To suppose that the meanest use for the finest lines should be meaner than the meanest use for merely fine lines, or lines in general, is to commit something like the Conjunction Fallacy.
Now return to the Greatest Happiness Principle. If it means to pick out the possible situation containing the most happiness then we can object in Fowler fashion. The state of affairs containing the greatest happiness for the greatest number is unlikely to be the one containing the greatest happiness, since the situations in which the greatest number are happy is a subset of situations in which anyone is happy. To assume otherwise is to fall into the Conjunction Fallacy (or maybe not — Bentham had independent reasons for supposing that all the situations with the greatest net happiness were all ones in which the happiness was spread across the greatest number).
This is Geach’s critique. But it seems like a feature rather than a bug of the Greatest Happiness Principle. It is, after all, quite plausible to say that a situation in which two people are reasonably happy is morally preferable to one in which one person is enormously happy and the other suffers terribly. The point of including two superlatives in this case is precisely that both happiness and number are important enough to be emphasised.
Go back to the Fowler sentence and imagine that the author wants to emphasise both the fineness of the lines and the meanness of the use. Now the sentence serves its purpose perfectly. Likewise, I think, with the Greatest Happiness Principle.
So I don’t understand Geach’s critique, unless it is simply that calling the principle “The Greatest Happiness Principle” is false advertising. But if it were called “The Greatest Happiness for the Greatest Number Principle” then its name would be longer than itself.
