 Fideism. Deism or natural religion of various sorts tends to rely on the claim that reason or human experience supports the hypothesis that there is a supreme being who created or authored the world. In one of the most important philosophical texts on natural religion to appear during the Enlightenment, David Hume’s Dialogues Concerning Natural Religion (published posthumously in 1779), this supposition is criticized relentlessly, incisively and in detail. Naturally, the critical, questioning attitude characteristic of the Enlightenment in general is directed against the arguments on which natural religion is based. In Part Nine of the Dialogues, Samuel Clarke’s “argument a priori” (as defended by the character Demea) is dispatched fairly quickly, but with a battery of arguments. But Hume is mainly concerned in the Dialogues with the other major pillar of natural religion in the Enlightenment, the “empirical” argument, the teleological argument or the argument from design. Cleanthes, the character who advances the design argument in the dialogue, proceeds from the rule for empirical reasoning that like effects prove like causes. He reasons that, given the resemblance between nature, which displays in many respects a “curious adaptation of means to ends”, and a man-made machine, we must infer the cause of nature to be an intelligence like ours, though greater in proportion as nature surpasses in perfection the products of human intelligence. Philo, the skeptical voice in the Dialogues, presses Cleanthes’ argument on many fronts. He points out that the argument is only as strong as the similarity between nature or parts of nature and man-made machines, and further, that a close scrutiny reveals that analogy to be weak. Moreover, according to the principle of the argument, the stronger the evidence for an author (or authors) of nature, the more like us that author (or authors) should be taken to be. Consequently, according to Philo, the argument does not support the conclusion that God exists, taking God to be unitary, infinite, perfect, et cetera. Also, although the existence of evil and disorder in nature may serve actually to strengthen the case for the argument, given the disorder in human creations as well, the notion that God authors evil and disorder is disturbing. If one denies that there is disorder and evil in nature, however implausibly, the effect is to emphasize again the dissimilarity between nature and human products and thus weaken the central basis of the argument. With these and other considerations, Philo puts the proponent of the empirical argument in a difficult dialectical position. But Cleanthes is not moved. He holds the inference from the phenomenon of the curious adaptation of means to ends in nature to the existence of an intelligent and beneficent author to be so natural as to be impervious to the philosophical cavils raised by Philo. And, in the ambiguous conclusion of the work, Philo seems to agree. Though Hume himself seems to have been an atheist, one natural way to take the upshot of his Dialogues is that religious belief is so “natural” to us that rational criticism cannot unseat it. The ambiguous upshot of the work can be taken to be the impotence of rational criticism in the face of religious belief, rather than the illegitimacy of religious belief in the face of rational criticism. This tends toward fideism, the view according to which religious faith maintains its truth over against philosophical reasoning, which opposes but cannot defeat it. Fideism is most often associated with thinkers whose beliefs run contrary to the trends of the Enlightenment (Blaise Pascal, Johann-Georg Hamann, Søren Kierkegaard), but the skeptical strain in the Enlightenment, from Pierre Bayle through David Hume, expresses itself not only in atheism, but also in fideism.