Could it yet be possible that there are moral truths even if we cannot establish them by reason alone? The existence of transcendent, objective moral truths that we might somehow discover seems unlikely, though many or most believe in their existence (Joyce, 2010 has suggested that most moral philosophers — though not most of all philosophers — are probably believers, or they would have been unlikely to pursue moral philosophy). A more practical moral realism might mean that at least some principles exist which provide a path to a life which any one would choose if informed and freely able to choose (or they would at least be better off if they made such a choice). Such a morality might provide a key less to external nature than to the internal nature of a person (or perhaps all persons) — to psychology. It seems at least possible that some prohibitions — e.g., that it is wrong to murder innocents — could fit this description given how widely shared are both the prohibitions and the belief of the effect on the individual of violating them; or, conversely, that some positive principles really exist, given the broad and cross-cultural desirability of certain character virtues such as courage. But prohibitions and principles it would be irrational not to follow are still short of moral obligations one is commanded to follow (though some feel otherwise). It also seems unlikely that there are moral truths of any kind that apply to all behaviors considered morally relevant given what we can see of the complex way psychological nature unfolds through biology and environment and the range of opinion on and apparent effects of various behaviors. Nietzsche for one thought authenticity and the exercise of the will more important than compassion. More conventionally, the split between conservative and liberal attitudes found in so many societies suggests at least a bifurcated set of moral principles and possible root psychology.
(Revised December 31, 2009)