Seth Shostak and Alex Barnett. Cosmic Company: The Search for Life in the Universe. Cambridge University Press, 2003.
Simon Conway Morris. Life's Solution: Inevitable Humans in a Lonely Universe. Cambridge University Press, 2003.
The debate about the possibiliyies of ET continue unabated, and Shostak and Barnett's book is one of the latest in the field. It is primarily an illustrated coffee table introduction which briefly summarizes the various arguments, including a short piece on UFOs which offers no comfort to the believers.
Shostak and Barnett take the general view that ET life is unlikely to closely resemble the terrestrial variety, and that if the tape of life on earth were rerun and rerun, each time the outcome would be different. This thesis is challenged by Conway Morris, in a book which my psychic powers allow me to predict will be quoted on numerous occasions by certain 'scientific ufologists' and their friends. Morris argues that only a very limited number of the vast variety of potential evolutionary pathways are likely to be followed, basing much of his argument on evolutionary convergence, the process by which eyes, for example, have developed on several different occasions; that dolphins resemble fish; and that there are marsupial equivalents of many placental mammals.
The general explanation of this is that it is that creatures which adapt to similar environments will have superficial similarities, but Morris takes the idea of converge to a more general level. More general, and it must be said more technical level, so that it is difficult for the lay reader to follow much of the argument.
Arguing from convergence Morris suggests that 'humans' - that is tool using, intelligent bipeds - are equally inevitable. Here the argument seems to creak; after all where are the marsupial people, or indeed the 'people' descended from the New World monkeys? Ah well, says Morris, given enough time who knows what might happen? There is an aura of faith about all this.
Morris seems to be on even more shaky ground when arguing that the small number of planets on which complex life might develop will also evolve their equivalent of apes and people. Surely life evolves in response to the particular environments in which it develops? Well, here again Morris tends to appeal less to Darwinian natural selection than on generalities and laws of form.
Just why this is so is partially explained by the last chapter in which a religious agenda is revealed, complete with rants against Richard Dawkins and his ilk and against genetic engineering. Of course there are non-sequitors here, a theist could equally argue that God created a universe based on contingency as the best means of producing the maximum diversity of lifeforms and hence 'the experience of being', or alternatively that the universe is designed for the maximum production of rational, moral beings, whether physically resembling human beings or not, or that the development of genetic engineering is part of God's plan for humanity. Indeed you can probably assemble theological arguments for any proposition you wish, which is why they have no place in science or politics.
Morris's argument seems to be the weakest of all, that human beings as rational moral beings are very special but very rare. Presumably he must believe that either God knows that a 200km asteroid is not going to hit the earth until humans have colonized the solar system and beyond, or he is intervening to prevent this, which leads to all sorts of curious moral paradoxes (e.g. why did God not prevent Kaiser Frederick of Germany developing cancer, and thus prevent the two world wars, the holocaust, Russian revolution, Mao's revolution in China, etc, and save at least 100 million lives).
The answer as to why Morris chooses this risky strategy, is that behind the more overt religious agenda, is a narrower covert one. For Morris is not arguing from general theism, but from his own rather politically corrected, greenified brand of traditional high church Anglicanism. And traditional Christians, unlike say Buddhists or Moslems, have real problems with ET life, because of the doctrine of the Incarnation. The Son of God may incarnate a few times, as say a Vulcan, or, at a pinch, a Klingon is just about tolerable, but as say a 27-tentacled silicon-based quasi-mollusc swimming in seas of hydrogen fluoride? That is just too aesthetically unpleasing, and trillions of times is out of the question.
From the viewpoint of scientific naturalism the question as to whether Conway Morris or Stephen J Gould is the more nearly right is an empirical one, which awaits the discovery of ET life forms for an answer. -- Peter Rogerson. Originally published March 2004