In short form, Hawkes' argument comes down to the idea that Gould's hypothesis of punctuated equilibrium, opens the door to external forces effecting the evolutionary processes. Hawkes then gives the mass extinctions caused by an asteroid (K-T event, Alvarez hypothesis) as such a potential external force and argues that evolutionary theory has been in trouble making the necessary modifications to a dogma of gradualism.
``...paleontology testifies that evolutionary stasis is the norm, and that change takes place in abrupt bursts, as though suddenly spurred forward by some external stimulus...''
This possibility then argues against Darwin's position that competition and incremental natural selection was the sole arbiter of evolution.
Hawkes argues, once the door of external causation is open, it allows Gould to go beyond Darwin and effect a paradigm shift. Hawkes then intimates but doesn't quite say, that once that causal door is open, there is a much bigger problem waiting, which he accuses Gould of dodging, and that is the re-entrance of metaphysics into the room.
I already know from past e-mail exchanges on Bad and reading his book that Hawkes wants to go after a purely mechanistic, material, and reductionist world view---essentially to re-open the doors of the natural world to a credible examination by philosophy---based roughly on the idea that being or the non-material can not arise solely from the material.
That is probably a poor rendition, but it sketches it out. I'll have to read Gould to find out more and refresh my memory of some of these arguments.
There are a lot completely material and empirical routes out of these dilemmas that neither Hawkes or (possibly Gould) has explored.
Chuck Grime