The thought police: The unbearable lightness of logical conclusions

When my son Maxwell was a toddler, he did not believe he was ever an infant. This scepticism became manifest when he started identifying himself in photographs. Maxwell was accurate with photographs that were taken after age six months. But he dismissed earlier pictures as photographs of "BABIES".

I tried to persuade Maxwell that he was once a baby by turning the pages of his photograph album in reverse chronological order. Since we were now beginning with the most recent photographs, Maxwell was quite confident: "THAT'S ME!". Eventually his ME!s dwindled to MEs, which were followed by Mes, then mes. We then reached a point when Maxwell stopped making identifications. He just smiled awkwardly, shrugged and made this sound: "Ummm..."

I told a friend about how Maxwell had shrugged off my photographic refutation. She agreed that my argument had true premises. She agreed that the conclusion followed from the premises. But she defended the reasonableness of Maxwell's shoulder shrugging. She pointed out that the slippery slope could have been extended to sonograms of Maxwell. Did I think the ninth-month sonograms were Maxwell? The eighth month? The seventh month? Eventually I just smiled awkwardly, shrugged and made this sound: "Ummm..."

Oh, there are a few people willing to go "all the way". Not all of them are anti-abortionists. Japanese on both sides of the abortion debate concede that they were once fertilised eggs and that it is appropriate to pray at special grave shrines for the souls of aborted foetuses. Perhaps some Japanese are willing to go back further to scattered people composed of yet-to-be-united sperm and eggs. Rewinding further, we reach proto- sperm and proto-eggs. And then the increasingly scattered stuff that went into all THAT. Hence, we "discover" that each person has a kind of diffuse, backward immortality.

Maxwell's reaction to the slippery-slope argument is more sensible than this metaphysics of beginningless human beings. I say this not because there are philosophers who would agree with Maxwell's scepticism about having once been a baby. (The old Bertrand Russell questioned whether he was the same person as the young Bertrand Russell.) What makes Maxwell's shoulder-shrugging more sensible is his instinctual reluctance to follow the argument wherever it leads. Contrary to the advice of Socrates, we should treat the strangeness of our conclusions as a reason to doubt our reasoning. These doubts will lead us to reject sound arguments when their conclusions are strange but true. But we need this simple form of quality- control to rationally re-shape our sense of the absurd - in baby steps.

Roy Sorensen is a professor of philosophy at New York University.