Chapter 1 of the Mackie book covers Hume's account of miracles, which we discussed in our Hume epistemology episode. One of our blog commenters here mentioned offhand that he thought that argument had been long discredited, which was a surprise to me.
You can review the argument at Wikipedia here. Basically it boils down to "extraordinary claims require extraordinary evidence." We have plenty of experience of people lying, but (and this is an appeal to your own experience) no experience of the laws of nature being evidently contravened for special happenstances. Though miracles may in fact occur, we're never epistemically justified in believing them. Though Hume nominally leaves room for revelation being a route to bypass normal epistemic procedures, Mackie for one just thinks Hume was doing lip service to this principle to minimize his political trouble.
Mackie thinks that arguing for miracles is especially tricky because you have to both argue that there are laws of nature, and that these can be contravened divinely. It's not enough that there might be some experienced regularities, but that we're ignorant of the mechanism behind these and so could run into apparent exceptions to the rules we've established. It's that, yes, these are laws working deterministically within a closed system, yet God can set them aside at will. From p. 26:
Where there is some plausible testimony about the occurrence of what would appear to be a miracle, those who accept this as a miracle have the double burden of showing both that the event took place and that it violated the laws of nature. But it will be very hard to sustain this double burden. For whatever tends to show that it would have been a violation of natural law tends for that very reason to make it most unlikely that it actually happened. Correspondingly, those who deny the occurrence of a miracle have two alternative lines of defence. One is to say that the event may have occurred, but in accordance with the laws of nature. Perhaps there were unknown circumstances that made it possible; or perhaps what were thought to be the relevant laws of nature are not strictly laws; there may be as yet unknown kinds of natural causation through which this event might have come about. The other is to say that this event would indeed have violated natural law, but that for this very reason there is a very strong presumption against its having happened, which it is most unlikely that any testimony will be able to outweigh. Usually one of these defences will be stronger than the other. For many supposedly miraculous cures, the former will be quite a likely sort of explanation, but for such feats as the bringing back to life of those who are really dead the latter will be more likely. But the fork, the disjunction of these two sorts of
explanation, is as a whole a very powerful reply to any claim that a miracle has been performed.
For one point of view in contrast to Hume's, I was just looking at a description of Scottish philosopher George Campbell (1719-1796) in the Stanford Encyclopedia of Philosophy:
Campbell's opening move against this argument is to reject Hume's premiss that we believe testimony solely on the basis of experience. For, according to Campbell, there is in all of us a natural tendency to believe other people. This is not a learned response based on repeated experience but an innate disposition. In practice this principle of credulity is gradually finessed in the light of experience. Once testimony is placed before us it becomes the default position, something that is true unless or until proved false, not false unless or until proved true. The credence we give to testimony is much like the credence we give to memory. It is the default position as regards beliefs about the past, even though in the light of experience we might withhold belief from some of its deliverances.
Because our tendency to accept testimony is innate, it is harder to overturn than Hume believes it to be. Campbell considers the case of a ferry that has safely made a crossing two thousand times. I, who have seen these safe crossings, meet a stranger who tells me solemnly that he has just seen the boat sink taking with it all on board. The likelihood of my believing this testimony is greater than would be implied by Hume's formula for determining the balance of probabilities.
I personally don't find Campbell's response at all convincing: as Mackie points out, our judgments of likelihood are based on a body of background knowledge, so the antecedent improbability of a miracle is much greater than that of a ferry sinking (which was presumably not unheard of for ferries, even if one had never personally witnessed this happening). If readers have additional online sources they wish to point out against Hume's point, feel free to post some links and/or arguments as comments to this post.
-Mark Linsenmayer
What is the question here? If there is a god of the kind asserted in for instance the bible, then ‘the whim or purposes of god’ becomes part of the freak circumstances Hume insists must obtain. Hume is saying ‘because I’m sure there’s no God, there is a perfect naturalist explanation for any reported miracle and thus they are not evidence’. Ok, but let’s not think that a practical approach to rejecting the importunings of your pious friends is a knock-down argument against the possibility of miracles.
This doesn’t sound like you’re getting the epistemic argument here. He’s not saying God doesn’t exist or that miracles couldn’t occur, but only what is required given our condition as finite, mortal humans for us to have a justified belief about something. This is in the context of natural theology, where you think religious beliefs can be supported by ordinary empirical evidence. If you want to retreat to faith as something not requiring such evidence, then that’s fine; it’s just not natural theology any more. Mackie brings this up because miracles are, he thinks, an often cited reason why people believe in the first place (I can say personally that as a kid, this was pretty persuasive to me: Jesus showed he was awesome by doing all this crazy shit in front of lots of people.), and he’s trying to counter this as an argument for the existence of God. The counter doesn’t just assume that God doesn’t exist; it just says that reports of miracles aren’t going to be reliable enough to count as positive evidence.
It’s true, my knowledge of philosophy is mostly pieced together from the back of cereal boxes (like grampa simpsons American history). Hence your appeal for citations, I guess. I’m pretty sure the Vatican standard for miracles would read something like Hume’s, yet they find lots of miracles (and to be honest I adopt Hume’s line on most of them, because I don’t believe in saints).
What counts for Hume as ordinary evidence? I guess he’s living in a time of science and lots of mysteries are unravelling, and lots of received wisdom is being junked. It would be natural enough to throw reports of miracles out with phlogiston theory. On the evidence of Hume’s life and time, presuming against miracles like this seems low risk. But that is all he is doing. It’s the classic commit it to the flames, isn’t it? Even in his time, he has to believe Kepler’s claims that he observed a star in a certain place at a certain time. These days we all learn so much that most of our ‘knowledge’ rests on authority instead of experience. (Miracles are aberrant events plus interpretation as to authorship of them).
As you probably know, there is some math that deals with deriving and supporting hypotheses from experience: probability and confidence statistics. I think Hume is asserting that 50% confidence evaluations of the world are all we can have. It’s nice, but it’s a manifesto not an argument. (I’m composing this on an iPhone and it has made it difficult to edit. Apols for bad structure. Ok, probably embarrassed self and other theists enough for one discussion.)
Mackie does allow that talk of miracles is acceptable in the context that if you’ve already bought into a model of science in which miracles are possible, then you can argue about what constitutes a miracle or not (which is I guess what the Vatican does).
I don’t think you’re right re. Hume being committed to 50/50 confidence values re. things we don’t know. The entire point is that we do develop expectations directly in proportion to well-grounded evidence we already have. So we’d actually have some rough percentages for judging the likelihood of an alleged new event, and miracles would antecedently have a very very low likelihood (which the advocate for miracles also accepts: that’s what makes them miraculous).
Would this rule out cutting-edge science? Well, if someone claims to have looked in a telescope once and seen something totally unexpected, that would uproot the whole system of science as currently widely accepted, should we believe his testimony? No, not without double checking it. Others should be able to look at the same thing and witness that phenomena, and Hume says the same thing about miracles. If you actually have multiple witnesses (as opposed to, say, multiple sources that all ultimately rely on the same parent source or alleged witness), that greatly decreases the likelihood of someone lying.
I think it is legitimate to ask whether Hume’s argument is too sweeping: if, e.g. a whole group of people witness something miraculous, would Hume then be committed to say it MUST have been a group delusion or trick? That would still be the default position (or else David Copperfield would have to be called a miracle worker), but presumably, if a real miracle occurs, you’d have verifiable evidence: e.g. if someone allegedly returns from the dead, then you’ll have the documentation and witnesses that the person was dead, and then you can do whatever tests on the re-animated fellow to confirm that it’s the same person, etc. It would just take a lot of doing to prove it, and moreover, as Mackie pointed out, how would you know it was a bona fide one off miracle and not something about the regular laws of nature that we just didn’t know about before? Scientists assume the latter and try to look for a pattern to make sense of the new data, which is arguably begging the question against it just being miraculous, with no explanation.
Robert Fogelin’s 2003 book “A Defense of Hume on Miracles” should be of interest. I have it but even though it looks like a very quick read of only 60+ pages I didn’t get around to reading it yet. So I can’t testify to its quality, but I have no doubts about the competence of Fogelin.
From what I’ve gathered Fogelin thinks Hume’s argument is often misrepresented and has been dumbed down a little by its critics, and that it is, in its original form, a more profound and compelling argument than many have come to think.
But like I said, I didn’t read the book yet, so my words on this should be taken with a grain or two of salt. I’m just trying to spark an interest. 🙂
Since the main discussion has moved on, I would like to make a face- and conscience-saving follow up, very quietly adding some links and some clarification. First some links:
http://www.infidels.org/library/modern/victor_reppert/miracles.html
This article is basically making the point, fairly intelligently, that Christians expect the world to bear some evidence of miracles, and accept testimony of miracles which David Hume thinks he knows better about. The different credence functions are the confidence discounting which I was trying to allude to. Hume has great confidence in the representationality of his life experience, and is happy to discount other people’s accounts heftily on the basis of it. (Pascal’s wager is an interesting variation – you evaluate the probability and even if you conclude Christianity is true only one chance in a hundred, you should adopt it precautionarily.).
This essay is also good in that it affirms that Christians do expect real testable evidence of a freak occurrence when a miracle happens, and that some things are disconfirming (e.g. the flood has not shown up as a world-wide catastrophe, which is a black eye for the historians of 4000+ years ago, and people who believed them literally).
Here is a summary of the vatican process for identifying miracles: http://www.yalibnan.com/2011/01/15/how-does-the-vatican-decide-whats-a-miracle/. There has to be evidence of two very improbable events, and each has to have occurred under the auspices of some canonisation candidate (which is how you make Mackie’s discrimination – if high energy Xrays from a supernova light years away knock out the cancer-generating stem cell and you recover, its a freak occurrence. If that freak occurrence coincides with a relevant speech act, and if the coincidences start to mount up, then maybe the speech acts are telling you something).
Here is a review of Fogelin.
http://www.humesociety.org/hs/issues/v31n1/otte/otte-v31n1.pdf
It is positive about Fogelin, but the review hints that to defend Hume on miracles he is interpreting him rather differently from conventional scholars. A bit above my pay grade, but I took heart that there is a scholarly work called ‘Hume’s Abject Failure’ on his miracles essays. (Although I seem to be a ‘gross misreader’ (because I think Hume has a ‘no true scotsman’ approach to claims of miracles) which is disappointing. Back to the books I guess.)
Finally, I think the idea that we believe things only (or even primarily) on the background of our experience is not quite right. We actually depend vitally on others to understand, to confirm and refute a lot of hypotheses that we entertain early in life. Our understanding of the world will ideally be coherent with our daily experience (we experience terrible anxiety if they are at odds) but we, of necessity, hold and act on a lot of beliefs that extend implications far beyond our experience.