Abstract

[opening paragraph]: Today, the planet has plenty of conscious beings on it; three billion years ago, it had none. What happened in the interim was a lot of evolution, with features emerging gradually, in one order or another. Figuring out what order and why is very likely a good way to reduce perplexity, because one thing we have learned from the voyage of the Beagle and its magnificent wake is that puzzling features of contemporary phenomena often are fossil traces of earlier adaptations. As the great biologist D'Arcy Thompson once said, ‘Everything is the way it is because it got that way'. And even when we can't remotely confirm our Just So Stories about how things got the way they are, the exercise can be salutary, since it forces us to ask (and try to answer) questions that might otherwise never occur to us. We do have to get the left and right sides of our equation to match in dimensionality -- I am grateful to Humphrey (2000) for this useful proposal about how to think about the issues -- and adding wrinkles on the right needs to be motivated by, and in the end justified by, more than the sheer need for a few more dimensions. As Just So Stories go, Humphrey's account of the emergence of sensation is a valuable one, traversing ground that must be traversed one way or another, and providing along the way some reasonable grounds for supposing things happened roughly the way he supposes.