scientists that spontaneous generation is a bad theory. A conjuring trick cannot have been performed by real magic – by the magician simply commanding events to happen – but must have been brought about by knowledge that was somehow created beforehand. Similarly, biologists need only have asked: how does the knowledge to construct a mouse get to those rags, and how is it then applied to transform the rags into a mouse?
One attempted explanation of spontaneous generation, which was advocated by the theologian St Augustine of Hippo (354–430), was that all life comes from ‘seeds’, some of which are carried by living organisms and others of which are distributed all over the Earth. Both kinds of seed were created during the original creation of the world. Both could, under the right conditions, develop into new individuals of the appropriate species. Augustine ingeniously suggested that this might explain why Noah’s Ark did not have to carry impossibly large numbers of animals: most species could regenerate after the Flood without Noah’s help. However, under that theory organisms are not being formed purely from non-living raw materials. That distributed kind of seed would be a life form, just as a real seed is: it would contain all the knowledge in its organism’s adaptations. So Augustine’s theory – as he himself stressed – is really just a form of creationism, not spontaneous generation. Some religions regard the universe as an ongoing act of supernatural creation. In such a world, all spontaneous generation would fall under the heading of creationism.
But, if we insist on good explanations, we must rule out creationism, as I have explained. So, in regard to spontaneous generation, that leaves only the possibility that the laws of physics might simply mandate it. For instance, mice might simply form under suitable circumstances, like crystals, rainbows, tornadoes and quasars do.
That seems absurd today, because the actual molecular mechanisms of life are now known. But is there anything wrong with that theory itself, as an explanation? Phenomena such as rainbows have a distinctive appearance that is endlessly repeated without any information having been transmitted from one instance to the next. Crystals even behave in ways that are reminiscent of living things: when placed in a suitable solution, a crystal attracts more molecules of the right kind and arranges them in such a way as to make more of the same crystal. Since crystals and mice both obey the same laws of physics, why is spontaneous generation a good explanation of the former and not of the latter? The answer, ironically, comes from an argument that was originally intended to justify creationism:
The argument from design
The ‘argument from design’ has been used for millennia as one of the classic ‘proofs’ of the existence of God, as follows. Some aspects of the world appear to have been designed, but they were not designed by humans; since ‘design requires a designer’, there must therefore be a God. As I said, that is a bad explanation because it does not address how the knowledge of how to create such designs could possibly have been created. (‘Who designed the designer?’, and so on.) But the argument from design can be used in valid ways too, and indeed its earliest known use, by the ancient Athenian philosopher Socrates, was valid. This issue was: given that the gods have created the world, do they care what happens in it? Socrates’ pupil Aristodemus had argued that they do not. Another pupil, the historian Xenophon, recalled Socrates’ reply:
SOCRATES: Because our eyes are delicate, they have been shuttered with eyelids that open when we have occasion to use them . . . And our foreheads have been fringed with eyebrows to prevent damage from the sweat of the head . . . And the mouth set close to the eyes and nostrils as a portal of ingress for all our supplies, whereas, since matter passing out of the body is unpleasant, the outlets are directed hindwards, as far away from the senses as possible. I ask you, when you see all these things constructed with such show of foresight, can you doubt whether they are products of chance or design?
ARISTODEMUS: Certainly not! Viewed in this light they seem very much like the contrivances of some wise craftsman, full of love for all things living.
SOCRATES: And what of the implanting of the instinct to procreate; and in the mother, the instinct to rear her young; and in the young, the intense desire to live and the fear