We have many many evidence that random mutation is enough for describing the biological evolution on Earth. If the mutation is controlled by someone than it is done according to random distributions as far as we currently know. He should provide evidence if he thinks otherwise but he is not doing it and not qualified for it, thats only what I see.
>He should provide evidence if he thinks otherwise
That's what he does in the book. But Nagel isn't claiming to make any original contribution to biology or evolutionary theory. His main aim, as far as I can see, is to point out that the standard arguments for mutations being random are less strong than is usually thought. I don't think he claims to know whether or not mutations are in fact random, or what controls them if they are not.
We have many many evidence that random mutation is enough for describing the biological evolution on Earth. If the mutation is controlled by someone than it is done according to random distributions as far as we currently know. He should provide evidence if he thinks otherwise but he is not doing it and not qualified for it, thats only what I see.