A miracle is "a transgression of a law of nature by a particular volition of the Deity, or by the interposition of some invisible agent" (Hume, 123n). Theologians of the Abrahamic religions consider only God-willed contravention of the laws of nature to be true miracles. However, they admit others can do and have done things which contravene the laws of nature; such acts are attributed to diabolical powers and are called "false miracles." Many outside of the Bible-based religions believe in the ability to transgress laws of nature through acts of will in consort with paranormal or occult powers. They generally refer to these transgressions not as miracles, but as magick.
All religions report numerous and equally credible miracles. Hume compares deciding among religions on the basis of their miracles to the task of a judge who must evaluate contradictory, but equally reliable, testimonies. Each religion establishes itself as solidly as the next, thereby overthrowing and destroying its rivals. Furthermore, the more ancient and barbarous a people is, the greater the tendency for miracles and prodigies of all kinds to flourish.
...it forms a strong presumption against all supernatural and miraculous relations that they are observed chiefly to abound among ignorant and barbarous nations; or if a civilized people has ever given admission to any of them, that people will be found to have received them from ignorant and barbarous ancestors, who transmitted them with that inviolable sanction and authority which always attend received opinions (Hume, 126).
While there are still many people today who believe in miracles, no modern historian fills his or her books with accounts of miraculous events. It is improbable that the report of even a single miracle would find its way into such texts today. Indeed, only those who cater to the superstitious and credulous, such as the Weekly World News and a good portion of the rest of the mass media, would even think of reporting an alleged miracle without taking a very skeptical attitude toward it. No scholarly journal today would consider an author rational if he or she were to sprinkle reports of miracles throughout a treatise. The modern scholar dismisses all such reports as either confabulations, delusions, lies or cases of collective hallucination.
Hume was aware that no matter how scientific or rational a civilization became, belief in miracles would never be eradicated. Human nature is such that we love the marvelous and the wondrous. Human nature is also such that we love even more to be the bearer of a story of the marvelous and the wondrous. The more wondrous our story, the more merit both we and it attain. Vanity, delusion and zealotry have led to more than one pious fraud supporting a holy and meritorious cause with gross embellishments and outright lies about witnessing miraculous events (Hume, 136). Hume's prediction is borne out every time there is a natural disaster that kills thousands and renders hundreds of thousands homeless. There is always some survivor who calls his survival a miracle, while ignoring the fate of the thousands of equally worthy fellows buried in the rubble all around him. The media, perhaps trying to find a small ray of hope amidst the despair of massive earthquakes or floods, love to print such 'miracle stories.'
Hume's greatest argument against belief in miracles, however, was modeled after an argument made by John Tillotson, Archbishop of Canterbury. Tillotson and others, such as William Chillingworth before him and his contemporary Bishop Edward Stillingfleet, had argued for what they called a "commonsense" defense of Christianity, i.e., Anglicanism. Tillotson's argument against the Catholic doctrine of transubstantiation or "the real presence" was simple and direct. The idea contradicts common sense, he said. The doctrine claims that the bread and wine used in the communion ceremony is changed in substance so that what is bread and wine to all the senses is in fact the body and blood of Jesus. If it looks like bread, smells like bread, tastes like bread, then it is bread. To believe otherwise is to give up the basis for all knowledge based on sense experience. Anything could be other than it appears to the senses. This argument has nothing to do with the skeptical argument about the uncertainty of sense knowledge. This is an argument not about certainty but about reasonable belief. If the Catholics are right about transubstantiation, then a book might really be a bishop, for example, or a pear might actually be Westminster Cathedral. The accidents (i.e., properties or attributes) of a thing would be no clue as to its substance. Everything we perceive could be completely unrelated to what it appears to be. Such a world would be unreasonable and unworthy of God. If the senses can't be trusted in this one case, they can't be trusted in any. To believe in transubstantiation is to abandon the basis of all knowledge: sense experience.
Hume begins his essay on miracles by praising Tillotson's argument as being "as concise and elegant and strong as any argument can possibly be supposed against a doctrine so little worthy of a serious refutation." He then goes on to say that he fancies that he has (118)
discovered an argument of a like nature which, if just, will, with the wise and learned, be an everlasting check to all kinds of superstitious delusion, and consequently will be useful as long as the world endures; for so long, I presume, will the accounts of miracles and prodigies be found in all history, sacred and profane.
His argument is a paradigm of simplicity and elegance (122):
A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined.
Or put even more succinctly (122):
There must...be a uniform experience against every miraculous event, otherwise the event would not merit that appellation.
The logical implication of this argument is that (123)
no testimony is sufficient to establish a miracle unless the testimony be of such a kind that its falsehood would be more miraculous than the fact which it endeavors to establish.
What Hume has done is to take the commonsense Anglican argument against the Catholic doctrine of transubstantiation and applied it to miracles, the basis of all religious sects. The laws of nature have not been established by occasional or frequent experiences of a similar kind, but of uniform experience. It is "more than probable," says Hume, that all men must die, that lead can't remain suspended in air by itself and that fire consumes wood and is extinguished by water. If someone were to report to Hume that a man could suspend lead in the air by an act of will, Hume would ask himself if "the falsehood of his testimony would be more miraculous than the event which he relates." If so, then he would believe the testimony. However, he does not believe there ever was a miraculous event established "on so full an evidence."
Consider the fact that the uniformity of experience of people around the world has been that once a human limb has been amputated, it does not grow back.1 What would you think if a friend of yours, a scientist of the highest integrity with a Ph.D. in physics from Harvard, were to tell you that she was off in Spain last summer and met a man who used to have no legs but now walks on two fine, healthy limbs. She tells you that a holy man rubbed oil on his stumps and his legs grew back. He lives in a small village and all the villagers attest to this "miracle." Your friend is convinced a miracle occurred. What would you believe? To believe in this miracle would be to reject the principle of the uniformity of experience, upon which laws of nature are based. It would be to reject a fundamental assumption of all science, that the laws of nature are inviolate. The miracle cannot be believed without abandoning a basic principle of empirical knowledge: that like things under like circumstances produce like results.
Of course there is another constant, another product of uniform experience which should not be forgotten: the tendency of people at all times in all ages to desire wondrous events, to be deluded about them, to fabricate them, embellish them, and come to believe in the absolute truth of the creations of their own passions and heated imaginations. Does this mean that miracles cannot occur? Of course not. It means, however, that when a miracle is reported the probability will always be greater that the person doing the reporting is mistaken, deluded, or a fraud than that the miracle really occurred. To believe in a miracle, as Hume said, is not an act of reason but of faith.
It is interesting to note that when the Roman Catholic Church collects data on potential saints, whose canonization requires proof of three miracles, the authorities ignore negative evidence. Millions may pray to a potential saint and all but one seems not to have had his wish granted. The Church counts the one who seems to have had her wish granted and ignores the millions who came up empty and died without intercession. Likewise, when the media report on natural disasters, they are fond of the story of the survivor who thanks God and basks in the glory of the miracle that saved him, but they never print a story blaming God for the thousands or hundreds of thousands who were killed in the earthquake or the tsunami. It doesn't occur to the survivor or the media that if it was just circumstance that led to the deaths of thousands, it was also merely circumstance that led to anyone surviving.