Morals are not the conclusions of reason, but a product of the group selection of cultural evolution. This favoured groups which practised certain moral traditions concerning private property, family and other social relations which were preserved often in opposition to the self-interested desires of individuals and without foreknowledge of their remote evolutionary effects. The adaptive success of groups that preserved these moral habits, their rules of conduct and the extended social cooperation they engendered made possible the growth of the human population to its present level.
Rationalists regard as valid only that which can be rationally justified according to three main criteria. Rationalism denies the acceptability of beliefs founded on anything but experience or reasoning. Positivism accepts as true only scientific knowledge describing the coexistence or succession of observable phenomenon. Utilitarianism takes the pleasure and pain of everyone effected by an action to be the sole criterion for that action's rightness. As moral traditions do not satisfy the conditions for truth set by rationalism, positivism and utilitarianism, they are rejected as irrational. This 'enlightenment' led to the socialist-progressive rejection of conventional morality and the construction of new projects for social justice and emancipation aimed at realising certain material ends. These projects are not only predicated on the logical error that morals are the product of our reason, but their fulfillment is unlikely to sustain the current level of the human population.
