If you like the science on this weblog, I highly recommend Laelaps, Brian Switek’s contribution to the ScienceBlogs network. Where I am more micro and anthro oriented he is more macro and spans the whole tree of life. I’m really glad he’s on ScienceBlogs; Laelaps adds to the diversity in an interesting way.
In any case, I wanted to point to this long post, Troodon sapiens?: Thoughts on the “Dinosauroid”, it mulls over many concepts and evolutionary processes. Brian highlights the alternative views of the paleontologists Stephen Jay Gould and Simon Conway Morris. While Gould emphasized historical contingency and overall stochasticity of evolutionary process, Morris tends to lean toward the power of selection generating convergent adaptations. Some have suggested that Morris’ views are influenced by his Christianity. Brian does note that this tendency toward teleology has correspondences with the talking points of the Intelligent Design movement, but I think it is important to observe that Richard Dawkins has come down on the side of Morris and against Stephen Jay Gould on this question. So the alignments here can be rather confusing to an outsider (some critics of adaptationism argue that the Oxford school of evolutionary biology, of which Dawkins is a representative, owes a great deal to William Paley’s arguments from design, simply substituting the theistic god for the blind engineer of selection).
On a philosophical note, I do think these arguments about contingency and inevitability have to framed within the context of time and space. Assuming enough evolutionary time and a large enough effective population size it is imaginable that contingency and constraint can eventually be circumvented as selection slowly explores every nook and cranny of the adaptive landscape. But of course that is assuming particular parameters; over shorter time periods stochastic forces can be critical in explaining the madness. What is a large effective population? And what is a long time period? There are assumptions often unspecified in these debates between those who argue for contingency and those who argue for inevitability, and I think quite often that results in talking past one another.