a theory of moral sentiments

Imagine twin infants in a crib. They're pretty new to this whole life thing, but they're slowly picking it up... sights and sounds that are repeated become familiar, some of them are associated with pleasure or pain. As these associations build up, they perhaps begin to experience anticipation, both positive and negative. When big sister's face appears over the horizon and she is smiling, they may feel a positive anticipation, because usually this means she is about to play with them or tickle them or sing to them. If she looks angry, though, they feel some apprehension, because sometimes she is resentful, and takes out her resentment by pinching their feet in not at all a nice way.

(By the way, this is a fable, not a treatise on child emotional development. I'd be interested to know in what order these various associations and emotions actually emerge, but it's beside the point here.)

One thing that neither of them knows is that they are twins. While to outsiders they are more or less a doubled unit, identical and interchangeable (and even in the family they are usually lumped together in talk as "the babies"), to themselves they are entirely different types of entity. One of them may indeed have noticed that there are four more or less identical feet in the crib-- but for two of the feet, when big sister tickles them, there is a delightful sensation and urge to laugh. For the other two, in appearance so similar, no shred of such sensation results. So clearly the four feet, though they look so similar, belong to two vastly different classes of object. So that, whether big sister tickles or pinches those two feet really makes little difference.

The infant may later observe that in fact it does make a difference whether the other two feet are tickled or pinched. First of all, the other object in the crib either laughs or cries, and if the object's laughter is pleasant and crying unpleasant, then the infant has good reason to prefer that the object be tickled. Second, if the object's feet are pinched, chances are that the infant's feet will be pinched imminently. The fate of the object's feet is a reliable indicator of the mood of the big sister, and for that reason too it makes a difference to the infant.

All this emotional range is quite plausible for the infant, and out of it may come a very strong appearance of sympathy. The infant doesn't like it when its twin's feet are pinched. He is likely even to begin expressing his dislike by crying even before his own feet are pinched. But the infant is worlds away, probably years away, from even beginning to have a real sympathy for his twin. The pinching of his twin's feet affects his world negatively; that is why he cries.

At some point, though, he makes the shocking discovery that that other object, the twin, is analogous to himself. It flies in the face of many observed facts (those feet produce no sensation! How can they possibly be like mine?), but there it is. The world must now be re-ordered to contain many subjects, not just one. He begins to understand that the twin's feet do produce sensation--for the twin. How odd.

Suppose, now that everybody is a little older, big sister has become more refined in her resentment. Instead of hating or loving both babies at once, she deals with her conflicted feelings by hating one of them and loving the other-- switching more or less randomly between each. (If you think this is implausible, consider the black sheep-white sheep phenomenon that arises in most families.) So any time she approaches the twins, she will tickle one's feet, and pinch the other's.

This changes the emotional landscape considerably. Now, for one of the babies, the pinching of the other feet means two things: the other twin will start to cry, which is unpleasant, and the sister will tickle his own feet, which is pleasant. And there is, too, in the back of his head the knowledge that the twin has experienced pain, very like what the infant himself would have experienced had the sister's wrath fallen on him instead. What does the child do? Does he cry because his twin is making such an infernal noise? Does he laugh because his feet are being tickled?

Or does he really, in a flash of inhuman insight, internalize the fact that, for the whole state of the universe, it makes no difference whose feet are pinched, his or his twin's? In the universe, someone's feet are being pinched-- whether the pinching happens to fall on my foot or my twin's matters only to the two of us, and only because we're so locked inside our own bodies. Whether the pulse of pain happens to flow to me or to my neighbor clearly is not the important thing: the important thing is that there is a pulse of pain.

And then the yet more unthinkable thought: is it the same for joy?