Monday, November 21, 2011

Don’t want to believe in evolution?

Is it possible to be a rationalist (a believer in the laws of logic) but not believe in evolution? Just about! But only just!

There are several philosophical show stoppers that bring rational argument to a halt.

Perhaps requiring the least mental gymnastics is the "Omphalos hypothesis", so-named after an 1857 book by English naturalist (and local Worcester man) Philip Gosse. Gosse argued that even if creation occurred from nothing, the creator would necessarily leave traces of previous existence that had never actually occurred. Although Adam was never hooked up to a placenta, he required a navel ("omphalos" in Greek) because it made him a complete human being. Similarly, God must have created trees with rings that they never grew and rocks with a fossil record of life that never actually existed.

This kind of thinking has drawn adverse responses from Catholic scientist Ken Miller and the "Zoo Rabbi" Natan Slifkin, who both reject it as depicting God as a dishonest charlatan. A secular response, Last Thursdayism, proposes, that by this logic, the world might just as easily have been created last Thursday, but with the appearance of age such as false memories and fictitious history books. There is even a parody religion, The Church of Last Thursday.

The first real philosophical show stopper is metaphysical solipsism: the belief that you, the reader, is all there is and that this blog and this author, this world and the evolution of life in it, are all just figments of your imagination. However, it is scarcely possible to hold this belief in your mind for even a minute and, as English philosopher Bertrand Russell once pointed out, solipsism
“is rejected in fact even by those who mean to accept it. I once received a letter from an eminent logician… saying that she was a solipsist, and was surprised that there were no others. Coming from a logician and a solipsist, her surprise surprised me.”
One modern variant on solipsism is the brain-in-a-vat idea, taken seriously by, among others, Berkeley philosopher Barry Stroud. In this scenario, your brain has been removed from your body, placed in a vat of life-sustaining liquid and your neurons hooked up to a supercomputer that provides you with a virtual reality indistinguishable from any “real” reality. So, the argument goes, if you are in a vat, all your conclusions about evolution in the real world are false. And, as you have no way of knowing whether you are in a vat or not, this leaves you free to doubt the reality of evolution.

But why suppose you ever had a body in the first place, why not suppose you are a disembodied brain created yesterday with false memories of a biological world built by evolution? Some cosmologists are seriously discussing the idea of Boltzmann brains, self-conscious entities that arise from random fluctuations in vacuum energy (named after Austrian physicist Ludwig Boltzmann, who suggested that the whole universe resulted from such a fluctuation). If the universe lasts long enough, such entities are inevitable, say the cosmologists. But why stop at a brain—viewing yourself as a Boltzmann-brain-in-a-vat breaks none of the laws of physics and also gets you off the hook of having to believe in evolution.

A more general case of the brain-in-a-vat idea is the simulation hypothesis. According to this viewpoint, popularized by the Matrix films, we are all living in a simulated reality, run on a computer powerful enough to create a internally consistent simulation, so detailed that it could not be distinguished from “real” reality. Swedish philosopher Nick Bostrom argues that it is more likely than not that we are living in such a simulation. His argument rests on the assumption that any sufficiently advanced civilization capable of creating simulations that contained intelligent individuals would be unlikely to restrict itself to a single simulation, instead, it would run billions of them. Thus, he asks, why suppose that we are the one civilization that develops the simulations rather than one of the billions run in simulation? Richard Dawkins points out that this merely pushes the need for evolution back stage as the only plausible source of the intelligences running the simulation.

Mathematical physicist Frank Tipler has controversially attempted to interweave cosmology, simulation and religion. He posits that as the universe comes to an end in a singularity, the computational capacity of the universe will outrun time, so that an intelligent civilization could run an infinite simulation within a finite time. Tipler borrows a term from Pierre Teilhard de Chardin to describe this final state of infinite information the Omega point. Recently, Tipler has come to identify his Omega point with God and to equate the associated infinite simulation with the resurrection of the dead. But why not assume we are already dead in Tipler’s sense, i.e. already living in his Omega point simulation and thus free to dispense with any direct evolutionary explanation for our own origins?

How is an evolutionary biologist to respond to all this? The obvious response is to adapt a line from George Orwell and say that you have to be a real philosopher to believe all that, no scientist could be so foolish! In fact, insofar as none of these scenarios is verifiable, they fall outside the realm of science and bring no additional explanatory power. So, you don't really have any excuses for dismissing evolution! Wise up and smell the cladogenesis!