A rudimentary light-sensitive cell or a very simple eye is better than nothing. Image-forming eyes have evolved independently at least forty times among vertebrates, and nine distinct eye structures can be identified, including pinhole, lens, curved reflector, and compound eyes. Moreover, says Dawkins, many systems in nature are far from perfect in their design. The human eye is "wired backward"; the nerves come out of the retina on the side toward the lens, obstructing the passage of light and requiring a hole in the retina for the nerves to leave the eye, creating a blind spot. No sensible designer would have made it that way, but evolutionary change always has to start from what is available and improve it, even if the end result is not the most efficient design.[i].
Dawkins points to the widespread suffering, pain and fear in nature, and the senseless tragedies that occur in human life.
In a universe of blind physical forces and genetic replication, some people are going to get hurt, and other people are going to get lucky, and you won't find any rhyme or reason in it, nor any justice. The universe that we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil, and no good, nothing but blind, pitiless indifference. . . . DNA neither cares nor knows. DNA just is. And we dance to its music.[ii].
Dawkins accepts epistemological reductionism: "The hierarchical reductionist believes that carburetors are explained in terms of smaller units . . . which are explained in terms of smaller units . . . which are ultimately explained in terms of the smallest of fundamental particles. . . . My task is to explain elephants, and the world of complex things, in terms of the simple things that physicists either understand, or are working on."[iii] He holds the view that science is the only acceptable form of explanation; if science does not discover purpose, there is no purpose in the universe.
