The theory of evolution, first proposed by Charles Darwin 150 years ago, is arguably the most important and powerful idea in the history of biology. Amongst all the sciences, it is difficult to imagine any idea more revolutionary in its promises, more satisfying in its rewards. Evolution unites the massive quantity of observed facts of the natural world into a whole. It takes modern life, the structure of the cell, the fossil record, etc. and from them tells a story.
Like so many powerful ideas, evolution has been misused, applied where it does belong. The results are not pretty. In particular I'm thinking of Social Darwinism. Essentially, this notion took Darwinian evolution and used it to rationalize prejudices of all varieties. Evolution says nothing about race or gender superiority/inferiority. It is also not hard to imagine evolutionary thought being taken further still, expanded to campaigns of mass euthanasia and sterilization. The history of eugenics in first half of the twentieth century shows clearly the harm that happens when perfectly legitimate ideas (like the natural survival of the fit and culling of the weak) and uses them to rationalize all manner of wickedness. It is the key observation of that doomed campaign of compulsory sterilization that the categories for the procedure were not based in any evidence, nor on any rationally supportable criteria. The poor and the non-white were the victims of this atrocity, instead of those who possessed actual genetic defect.
So what then are the bounds of Darwinism? What line divides legitimate and wicked applications of evolution? Simple. The natural world is Darwinian in structure. Evolution falls under the sphere of biology. This fact we must not lose sight of. Within biological considerations it's power is immense. Outside of the life sciences, it is often a tool poorly suited to the tasks before it. Our political theory ought not to be based upon an idea of evolutionary fitness. Instead we must follow that evolved compass of ours, morality.
To construct a society by Darwinian terms is non Darwinian.
Homo sapiens are communal creatures. The evolved faculties of compassion and morality and our insatiable desire for solidarity serve to unite us to stand together. We must not think of evolution in terms of organism. Rather we ought to think in terms of genes. A parent dying for a child makes sense because the genes will live. Further, it is basic biology that no species can survive or prosper with a too small gene pool. Thus we must (and have evolved to) consider more than our immediate offspring when making moral calculations.
Philosophy, my core discipline, does well to be productive. To return useful and applicable ideas is the greatest triumph the lovers of wisdom can achieve. So allow me to be plain.
We do not need an absolute code, divorced from human hands and minds, to rule us. By this I mean both religious doctrines and misapplications of scientific theories. We are evolved beings. This point is certain. And we will do well to trust those faculties evolution has yielded to us. Further, we should take advantage of the rich heritage available to us. Thinkers of all varieties have pondered over deep, difficult questions for thousands of years. If we trust our own moral sense, if we are honest about who and what we are (mammals capable of both greatness and depravity), and if we stand with each other, upon the shoulders of those who have come before us, then I suspect there is little we cannot achieve. The potential of the human species to better itself and its world is, practically speaking, without limit. We have only to make the choice to move in that direction.
This was the hope of those optimistic and visionary thinkers, like Clarke and Asimov, and it is most assuredly no fool's hope. It is the hope of all those who believe that more than darkness, something wonderful lies in the heart of man.