In the Times Richard Friedman, M.D. questions the widely debated evolutionary origins and/or advantages of depression. While happiness may not have been selected for survival advantage over the eons (emotional hypersensitivity, paranoia, and compulsivity have their uses in certain environments), he reminds us of the naturalistic fallacy, that is, we shalt not derive an ought from an is. We do not hesitate to decry genocide, bacterial infection, or "nature red in tooth and claw" even though such phenomena are eminently natural.
Theoretically there is nothing, not even cheesecake or Youtube, outside of nature (there is only one reality after all), but practically human beings have always distinguished between realms of culture (that which we believe we have some power to modify) and nature (about which, like the weather, we can only ultimately talk and not do anything). And one doesn't have to be a tree-hugger to acknowledge some sublimity of nature as the realm from which we came and which remains ultimately beyond us. Insofar as nature has accomodated the evolution of human beings over a million years (and of life in general over several billion years), it constitutes a kind of metaphysical cradle that we do well to rock only gently. It is a comfort to know that countless galaxies are beyond the capacity of humanity to despoil. Confronted with nature's nearly infinite array of figurative knobs and levers, we eagerly push this or switch that, but it still remains quite possible that human civilization will drive life on earth into an ecological ditch over the next millenium. The birth of consciousness may turn out to have been a tragedy for the biosphere--or not.
And yet one does commit the naturalistic fallacy every day, every moment, as life itself is the fundamental is from which we derive the ought. Nietzsche's ideal of the "eternal recurrence," the willingness to live one's life over again, in every inevitable detail and infinitely many times, is the absolute expression of the naturalistic fallacy. Some fallacy. If the ought has no connection to the is, where else could it come from?