In classical antiquity
Miracles were denied even in classical antiquity. Thus, Cicero asserted that “nothing happens without a cause, and nothing happens unless it can happen. When that which can happen does in fact happen, it cannot be considered a miracle. Hence, there are no miracles.” Cicero qualified this statement, however, by saying that miracle stories may be necessary for the piety of ignorant folk. The 2nd-century pagan philosopher Celsus is less dogmatic in his attacks on Christianity: the Christian miracles are insufficiently attested and most improbable, but, even if they were genuine, they could hardly offset the miracles of the pagan world—e.g., the healings of Asclepius. This was the standard pattern of many religious polemics: miracles as such were not necessarily denied; only those claimed by the adversary were denied. When these could not be denied, they were ascribed to diabolic agency or to the fraudulent practices of priests or occasionally to a misinterpretation of essentially natural phenomena.
In the 18th and early 19th centuries
Rationalist criticism, although not completely absent in the Middle Ages, became a major factor in the 18th and 19th centuries. David Hume, a British empiricist and a skeptic, in the chapter “On Miracles” in his Enquiry Concerning Human Understanding argued that, given the general experience of the uniformity of nature, miracles were highly improbable and that the evidence in their favour was far from convincing. It should be emphasized that Hume, whose criticism led him to a denial of causality, did not dismiss miracles because they were inconsistent with causal law—as many other thinkers did, notably the Deists (those, especially British, who advocated a natural religion). Instead Hume insisted on the probability factor and thus on the importance of assessing historical evidence. Because all Christians agreed that biblical religion and the scheme of salvation set forth in it could be maintained only by stressing prophecy and miracle, there developed a vast body of literature, especially among Protestants, proving the authenticity of the Christian faith on the basis of the miracles recorded in the Bible. For many 18th-century thinkers, however, the vastness and complexity of the order of nature were even more impressive than any alleged exceptions to it. Thus, belief in miracles, although remaining an essential element of faith to good Christians, appeared as sheer superstition to the eyes of the torchbearers of Rationalist enlightenment.
Criticism of the concept of miracle was articulated in more than one way. There was philosophical and scientific criticism to the effect that miracles were impossible and that even epistemologically (i.e., within the limits of knowledge) the occurrence of a miracle could never be established; at most, these critics maintained, there were merely as yet unexplained natural phenomena. (This view comes close to the religious assertion that faith precedes the experience of a miracle and that the factuality of a miracle can never precede faith.) There was historical and philological criticism, arguing that the actual occurrence of miracles is unsubstantiated and analyzing the growth and evolution of the legends and texts reporting miracles. There was psychological criticism, arguing that some people want to believe in miracles and so produce imaginative creations answering their psychological needs. There was also a type of religious criticism implying that the truly spiritual has no need of miraculous supports. One suggested solution to the problem was the assertion that the term miracle does not describe an objective event but rather a subjective mode of experience. This view of Friedrich Schleiermacher, an early-19th-century Protestant theologian and philosopher, identified miracle with a religious understanding of any aspect of the world.
In the late 19th and 20th centuries
Later 19th- and 20th-century liberal Protestant thinkers, such as Rudolf Bultmann, a German New Testament scholar, discarded the traditional notion of miracle together with other elements of what they termed the mythological apparatus of the Bible. Many of these liberal theologians sought evidence for Christianity in the moral and religious transformation it brought to people’s lives or interpreted the doctrine of salvation in Existential terms. The early decades of the 20th century, however, also witnessed a return to a more orthodox theological climate—as, for example, in the thought of Karl Barth, a Swiss Protestant theologian—and a new readiness to accept miracles as meaningful signs of God’s salvific activity. This change of climate coincided with certain developments in science that appeared to question a too rigid and mechanical concept of causal determinism.
Orthodox Jews, Christians, and Muslims still believe in the literal occurrence of the miracles recorded in their scriptures and traditions; Roman Catholics, furthermore, believe in the continued occurrence of miracles, defining them as a direct divine effect upon nature. The liberal attitude—whatever the variations in detail and in sophistication of the explanation—is essentially similar to that propounded by Schleiermacher.