Liberty, which has been vital to the West, derives from social commitment to search for truth and justice. Limiting reason to scientistic basis cripples that search, leading to pathologies such as promethean Marxism (social engineering), utilitarianism (undefined material progress), and Nietzschean will to power. Whereas the concept of logos, man’s foundational ability to reason deriving from supernatural rationality, connects reason with faith. The Greek concept, along with Jewish liberation of reason from myth and nature worship and Christian doctrines of God’s rational nature, natural law discernible to men, and human freedom to choose goodness and truth (plus universal brotherhood), form the basis of reason’s integration in the West. But from Bacon forward, faith was severed from reason and cast as superstition, while Locke asserted the human mind is shaped only by senses — there are no innate ideas. Scientism, core to radical empiricism, led to 19^th-century ‘faiths of destruction’: the aforementioned Marxism, utilitarianism, and will to power (which exhibits skepticism’s flaw, the claim to be strictly empirical, but whose first principle is itself groundless). The consequent ‘dictatorship of relativism’ – the collapse of confidence in reason to determine non-empirical truths – is a persistent threat. Islamic voluntarism – truth solely from revelation – and specifically terrorism cannot be contested by a liberalism enervated by flight from reason. Newman was the first to counter scientism; Benedict XVI is the author’s modern hero; logos is to be recovered.