David Hume's argument on miracles

From Internet Encyclopedia of Philosophy.  On miracles.

In Section X of his Enquiry Concerning Human Understanding, Hume tells us that it is not reasonable to subscribe to any “system of religion” unless that system is validated by the occurrence of miracles; he then argues that we cannot be justified in believing that a miracle has occurred, at least when our belief is based on testimony—as when, for example, it is based on the reports of miracles that are given in scripture. (Hume did not explicitly address the question of whether actually witnessing an apparent miracle would give us good reason to think that a miracle had actually occurred, though it is possible that the principles he invokes in regard to testimony for the miraculous can be applied to the case of a witnessed miracle.) His stated aim is to show that belief in miracle reports is not rational, but that “our most holy religion is founded on Faith, not on reason” (Enquiries, p. 130). Hume surely intends some irony here, however, since he concludes by saying that anyone who embraces a belief in miracles based on faith is conscious of “a continued miracle in his own person, which subverts all the principles of his understanding” (Enquiries, p. 131); this seems very far from an endorsement of a faith-based belief in miracles.

There is some dispute as to the nature of Hume’s argument against miracles, and the Enquiry seems to contain more than one such argument. The most compelling of these is the one I will call the Balance of Probabilities Argument. (For a brief discussion of some of the other arguments, see the entry “David Hume: Writings on Religion.”) Hume tells us that we ought to proportion our certainty regarding any matter of fact to the strength of the evidence. We have already examined some of the considerations that go into assessing the strength of testimony; there is no denying that testimony may be very strong indeed when, for example, it may be given by numerous highly reliable and independent witnesses.

Nevertheless, Hume tells us that no testimony can be adequate to establish the occurrence of a miracle. The problem that arises is not so much with the reliability of the witnesses as with the nature of what is being reported. A miracle is, according to Hume, a violation of natural law. We suppose that a law of nature obtains only when we have an extensive, and exceptionless, experience of a certain kind of phenomenon. For example, we suppose that it is a matter of natural law that a human being cannot walk on the surface of water while it is in its liquid state; this supposition is based on the weight of an enormous body of experience gained from our familiarity with what happens in seas, lakes, kitchen sinks, and bathtubs. Given that experience, we always have the best possible evidence that in any particular case, an object with a sufficiently great average density, having been placed onto the surface of a body of water, will sink. According to Hume, the evidence in favor of a miracle, even when that is provided by the strongest possible testimony, will always be outweighed by the evidence for the law of nature which is supposed to have been violated.

Considerable controversy surrounds the notion of a violation of natural law. However, it would appear that all Hume needs in order to make his argument is that a miracle be an exception to the course of nature as we have previously observed it; that is, where we have had a substantial experience of a certain sort of phenomenon—call it A—and have an exceptionless experience of all As being B, we have very strong reason to believe that any given A will be a B. Thus given that we have a very great amount of experience regarding dense objects being placed onto water, and given that in every one of these cases that object has sunk, we have the strongest possible evidence that any object that is placed onto water is one that will sink. Accordingly we have the best possible reasons for thinking that any report of someone walking on water is false—and this no matter how reliable the witness.

While objections are frequently made against Hume’s conception of natural law, in fact no particularly sophisticated account of natural law seems to be necessary here, and Hume’s examples are quite commonsensical: All human beings must die, lead cannot remain suspended in the air, fire consumes wood and is extinguished by water (Enquiries p. 114). This may be a naive conception of natural law; nevertheless it is true that, all things being equal, we can assign a minimal probability to the occurrence of a counterinstance to any of these generalizations.

At times Hume sounds as though he thinks the probability of such an event is zero, given its unprecedented nature, and some commentators have objected that the fact that we have never known such an event to occur does not imply that it cannot occur. Past regularities do not establish that it is impossible that a natural law should ever be suspended (Purtill 1978). However, regardless of Hume’s original intent, this is a more extravagant claim than his argument requires. He is free to admit that some small probability may be attached to the prospect that a dense object might remain on the surface of a lake; it is sufficient for his purposes that it will always be more likely that any witness who reports such an event is attempting to deceive us, or is himself deceived. After all, there is no precedent for any human being walking on water, setting this one controversial case aside, but there is ample precedent for the falsehood of testimony even under the best of circumstances.

Accordingly Hume says (Enquiries p. 115ff) that “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.” We must always decide in favor of the lesser miracle. We must ask ourselves, which would be more of a miracle: That Jesus walked on water, or that the scriptural reports of this event are false? While we may occasionally encounter testimony that is so strong that its falsehood would be very surprising indeed, we never come across any report, the falsehood of which would be downright miraculous. Accordingly, the reasonable conclusion will always be that the testimony is false.

Thus to return to Paul’s report of Jesus’ resurrection in 1 Corinthians: It may be highly unlikely that the original witnesses were wrong, for one reason or another, about whether they saw Jesus; it may be highly unlikely that the testimony of these witnesses may have been distorted before reaching Paul; it may be highly unlikely that Paul incorrectly reported what he heard about the event, and it may be highly unlikely that Paul’s original letter to the Christian community in Corinth has not been accurately preserved in our modern translations of the New Testament. Suppose the apologist can argue that a failure in the transmission of testimony at any of these points might be entirely without precedent in human experience. But the physical resurrection of a human being is also without precedent, so that the very best the apologist can hope for is that both alternatives—that the report is incorrect, or that Jesus returned to life—are equally unlikely, which seems only to call for a suspension of judgment. Apologetic appeals frequently focus on the strength of testimony such as Paul’s, and often appear to make a good case for its reliability. Nevertheless such an appeal will only persuade those who are already inclined to believe in the miracle—perhaps because they are already sympathetic to a supernaturalistic worldview—and who therefore tend to downplay the unlikelihood of a dead man returning to life.

Having said all this, it may strike us as odd that Hume seems not to want to rule out the possibility, in principle, that very strong testimony might establish the occurrence of an unprecedented event. He tells us (Enquiries p. 127) that if the sun had gone dark for eight days beginning on January 1, 1600, and that testimony to this fact continued to be received from all over the world and without any variation, we should believe it—and then look for the cause. Thus even if we were convinced that such an event really did take place—and the evidence in this case would be considerably stronger than the evidence for any of the miracles of the Bible—we should suppose that the event in question really had a natural cause after all. In this case the event would not be a violation of natural law, and thus according to Hume’s definition would not be a miracle.

Despite this possibility, Hume wants to say that the quality of miracle reports is never high enough to clear this hurdle, at least when they are given in the interest of establishing a religion, as they typically are. People in such circumstances are likely to be operating under any number of passional influences, such as enthusiasm, wishful thinking, or a sense of mission driven by good intentions; these influences may be expected to undermine their critical faculties. Given the importance to religion of a sense of mystery and wonder, that very quality which would otherwise tend to make a report incredible—that it is the report of something entirely novel—becomes one that recommends it to us. Thus in a religious context we may believe the report not so much in spite of its absurdity as because of it.