This is the third in my series of linked blog entries on my experience of being converted (or not) to intelligent design. Here I present the key arguments from the book What's Darwin Got to do with it? by Robert Newman, John Wiester and Janet and Jonathan Moneymaker, and how I respond to them.
- You can't necessarily argue from small scale to large - you can't take the example of (say) all the different shapes and sizes of dogs and draw the conclusion that you can evolve something from a single cell to a complex mammal. Seems fair - certainly in physics you can't apply the same rules to different scales. Micro-evolution accepted without question. Macro-evolution requires more evidence.
- Peppered moths aren't enough either - the famous increase of dark peppered moths in the industrial revolution demonstrates selectivity, but not evolution of drastically different species. Can't argue with this. (Similarly finch beaks.)
- Similarities between species doesn't necessarily imply common descent rather than design - the fact, for instance, that many mammals have very similar skeletal structures etc. is true but not useful. The fact that all cars are pretty similar in layout doesn't imply common descent rather than design.
- You can't use the bad design argument - This is one I've been guilty of. You point out that if biological entities are designed, they aren't perfectly designed. Look at our back-to-front optic nerves. Look at the panda's thumb. Y-e-e-s - but this is a theological argument, not a scientific one. ID doesn't say that an infallible God designed everything, just that there is evidence of design. (And let's face it, some biological 'design' is very good at what it does.)
- Transitional fossils are few and far between - MY FIRST CRY FOR HELP. Is this true? I know it used to be, and also there could be other reasons for this than they don't exist (e.g. transitions tended to coincide with geological circumstances that don't suit laying down of fossils). This was kindly answered by Henry Gee in my first posting: Yes. See this paper for a good, recent example. There is a problem, though, with 'transitional' fossils, as follows. In a sense they do not exist except in hindsight. As I have said elsewhere, evolution has no memory and no foresight, and only exists in the moment. Although we can pick up trends in the fossil recod after the fact, this doesn't mean that evolution runs on some kind of pre-ordained rails. I think creationists of all stripes think that that's how evolution works. Many evolutionary biologists certainly seem to think like that, or did until recently. This is not to deny that evolution happens, only to state trhat we should be more rigorous in defining what evolution is. Nevertheless, when I debunked the notion of progressive evolution in my book Deep Time there were howls of protest from evolutionary biologists complaining that I was giving ammo to the creationists. The existence of creationism has, to that extent, eroded free thought among evolutionary biologists, and this is something to be deplored.
- Everything since the Cambrian explosion has been variations on those 'basic designs' - SECOND CRY FOR HELP. Is this true? The book alleges that 'no animal phylum has appeared since [the Cambrian era].' Is this just a function of the way phyla are defined? This also was answered by Henry: [Yes], this is pretty much true.
- If SETI received a message that appeared to be designed, we would attribute it to intelligence, even though we have no evidence whatsoever of the existence of alien life. Why do we treat the possibility of intelligent design so differently? - Their best argument, I think - not for the correctness of ID, but for not dismissing it out of hand.
- What about irreducible complexity? - For me this turns out to be an argument against ID. The Victorian favourites the eye and the wing have both been shot to pieces; as far as I'm aware, the same has been done for 'rotary motors' propelling bacterial flagella. If irreducable complexity indicates design, you'd expect to see it all over, and you don't.
The other missing argument is the remarkably large overlap in the information content of DNA between different species. It really doesn't take too many changes to provide a change of species. [Added: and also there's the fundamental error made over and over again by those who query evolution, which is failing to recognise that evolution never sees a change of species from one generation to the next. Every individual is the same species as its parents, but paradoxically it is still possible to change over time. Divide a rainbow into billions of colours. It goes all the way through the colours yet each of your colour 'pixels' is indistinguishable from the previous one.]
Overall, then, I feel we need to take ID seriously, unlike creationism, because there is reasonable inferential evidence that is worth considering. And I will stop using the 'bad design' argument - that's not a scientific argument. (In my original post Stephen Curry queried this, but as I pointed out, 'bad design' is a theological argument. If we take ID at face value the designer does not have to be infallible.) But going on what this book can tell me I'm not persuaded that there is any reason why we couldn't see the changes an evolutionary model implies producing the variety of animals and plants we see today.
P.S. On my original post Bob O'Hara kindly listed these answers to my points above:
- I can't find anything for this, but anyway I agree to some extent: it would only be an argument if there was a perfect creator. I would disagree because some of the imperfections (e.g. the 10-15 foot detour in the giraffe1's nervous system) are better explained through common descent with modification.