Man's moral status, his moral experience and its alleged a priori conditions, have provided foundations for a variety of moral arguments for theism, generally purporting to be sufficient in themselves and independent of teleological considerations. In other words, the being of God has been inferred directly from human morality, and from morality alone. One form of moral argument is a posteriori and causal. A. R. Wallace, Lord Balfour, and others, have submitted that, inasmuch as natural selection cannot account for the origin of our higher moral sentiments, resort to a supernatural cause is necessary. Natural selection can only explain the emergence and persistence of such moral conduct and principles as possess survival-value for individuals or societies, between which the struggle for existence obtains; and survival-value does not pertain to the higher morality. But it would seem that naturalism can itself supply an explanation, rendering appeal to a divine cause unnecessary. Just as a bodily organ, developed in response to environment so as to fulfil a certain function, often proves, when acquired, to be capable of performing other functions also, and becomes a starting-point for developements in new directions, so may a mental functioning, once sufficiently developed to possess utility in the struggle for existence, be able of itself, or without further evocation from the environment, to develope to higher levels which, from Nature's point of view, are superfluous. The human mind, once having attained in the course of evolution to ideation, social intercourse, and language, is in a position to develope spontaneously, no longer controlled by mechanical selection (which is but rejection) but by its own interests and intrinsic potencies. From intelligence and emotional sensibility that are biologically useful it may proceed to disinterested science, to pure mathematics having no relation to the needs of life, to art, morality, and religion, no one of which products, rather than another, requires the intervention of a Deus ex machina to cause its emergence.
(F. R. Tennant, Philosophical Theology, vol. 2, The World, the Soul, and God [Cambridge: Cambridge University Press, 1930], 93-4)
