The appeal to "prior commitments" or "presuppositions" re. theism

Wednesday, August 25, 2010
Here's a bit from a paper forthcoming in Faith and Philosophy. I put it up because it concerns a certain move that's often made re evidence of miracles - that whether it's sensible to accept testimony of the miraculous depends on ones "presuppositions" or "prior commitments". This phrase just cropped up in a slightly bad-tempered interchange I am currently having with Glenn Peoples here.

The Ted and Sarah case

Suppose I have two close friends, Ted and Sarah, whom I know to be generally sane and trustworthy individuals. Suppose that Ted and Sarah now tell me that someone called Bert paid them an unexpected visit in their home last night, and stayed a couple of hours drinking tea with them. They recount various details, such as topics of conversation, what Bert was wearing, and so on. Other things being equal, it is fairly reasonable for me to believe, solely on the basis of their testimony, that such a visit occurred.

But now suppose Ted and Sarah also tell me that shortly before leaving, Bert flew around their sitting room by flapping his arms, died, came back to life again, and finished by temporarily transforming their sofa into a donkey. Ted and Sarah appear to say these things in all sincerity. In fact, they seem genuinely disturbed by what they believe they witnessed. They continue to make these claims about Bert even after several weeks of cross-examination by me.

Am I justified in believing that Ted and Sarah witnessed miracles? Surely not. The fact that Ted and Sarah claim these things happened is not nearly good enough evidence. Their testimony presents me with some evidence that miracles were performed in their living room; but, given the extraordinary nature of their claims, I am not yet justified in believing them.

Notice, incidentally, that even if I am unable to construct a plausible explanation for why these otherwise highly trustworthy individuals would make such extraordinary claims – it’s implausible, for example, that Ted and Sarah are deliberate hoaxers (for this does not fit at all with what I otherwise know about them), or are the unwitting victims of an elaborate hoax (why would someone go to such extraordinary lengths to pull this trick?) – that would still not lend their testimony much additional credibility. Ceteris paribus, when dealing with such extraordinary reports – whether they be about alien abductions or supernatural visitations – the fact that it remains blankly mysterious why such reports would be made if they were not true does not provide us with very much additional reason to suppose that they are true.

Consideration of the Ted and Sarah case suggests something like the following moral:

P1 Where a claim’s justification derives solely from evidence, extraordinary claims (e.g. concerning supernatural miracles) require extraordinary evidence. In the absence of extraordinary evidence there is good reason to be sceptical about those claims.

The phrase “extraordinary claims require extraordinary evidence” is associated particularly with the scientist Carl Sagan . By “extraordinary evidence” Sagan means, of course, extraordinarily good evidence – evidence much stronger than that required to justify rather more mundane claims. The phrase “extraordinary claims” is admittedly somewhat vague. A claim need not involve a supernatural element to qualify as “extraordinary” in the sense intended here (the claims that I built a time machine over the weekend, or was abducted by aliens, involve no supernatural element, but would also count as “extraordinary”). It suffices, for our purposes, to say that whatever “extraordinary” means here, the claim that a supernatural miracle has occurred qualifies.

Some theists (though of course by no means all) have challenged the application of Sagan’s principle to religious miracles, maintaining that which claims qualify as “extraordinary” depends on our presuppositions. Suppose we begin to examine the historical evidence having presupposed that there is no, or is unlikely to be a, God. Then of course Jesus’ miracles will strike us as highly unlikely events requiring exceptionally good evidence before we might reasonably suppose them to have occurred. But what if we approach the Jesus miracles from the point of view of theism? Then that such miraculous events should be a part of history is not, one might argue, particularly surprising. But then we are not justified in raising the evidential bar with respect to such claims. So theists may, after all, be justified in accepting such events occurred solely on the basis of a limited amount of testimony, just as they would be the occurrence of other unusual, but non-supernatural, events. The application of Sagan’s principle that “extraordinary claims require extraordinary evidence” to the Jesus miracles simply presupposes, prior to any examination of the evidence, that theism is not, or is unlikely to be, true. We might call this response to Sagan’s principle the Presuppositions Move.

That there is something awry with the Presuppositions Move, at least as it stands, is strongly suggested by the fact that it appears to license those of us who believe in Big Foot, psychic powers, the activities of fairies, etc. to adopt the same strategy – e.g. we may insist that we can quite reasonable accept, solely on the basis of Mary and John’s testimony, that fairies danced at the bottom of their garden last night, just so long as we presuppose, prior to any examination of the evidence, that fairies exist. Those making the Presuppositions Move with respect to religious miracles may be prepared to accept this consequence, but I suspect the majority of impartial observers will find it a lot to swallow – and indeed will continue to consider those who accept testimony of dancing fairies to be excessively credulous whether those believers happen to hold fairy-istic presuppositions or not.

I suspect at least part of what has gone wrong here is that, when it comes to assessing evidence for the Jesus miracles and other supernatural events, we do so having now acquired a great deal of evidence about the unreliability of testimony supposedly supporting such claims. We know – or at least ought to know by now – that such testimony is very often very unreliable (sightings of ghosts, fairies, and of course, even religious experiences and miracles, are constantly being debunked, exposed as fraudulent, etc.). But then, armed with this further knowledge about the general unreliability of this kind of testimony, even if we do happen to approach such testimony with theistic or fairy-istic presuppositions, surely we should still raise the evidential bar much higher for eye-witness reports of religious miracles or fairies than we do for more mundane claims.

{{ENDOTE It may be said that there is a relevant disanalogy between the application of the Presuppositions Move with respect to religious miracles and to fairies. We have now acquired good empirical evidence that there’s no such thing as fairies. Starting off an assessment of the empirical evidence with the presupposition that fairies exist is one thing. Retaining that presupposition in the teeth of empirical evidence to the contrary is quite another. The Presuppositions Move surely requires that we have come across no body of empirical evidence throwing into serious doubt the existence of what we have been presupposing exists. This blocks the application of the Presuppositions Move in defence of accepting testimony regarding fairies. However, while there’s good empirical evidence that there’s no such thing as fairies, there’s no such evidence against the existence of God. Thus the Move can still be made with respect to testimony of religious miracles.

An obvious difficulty with the above suggestion is the evidential problem of evil (for an assessment, see my “The Evil God Hypothesis” in Religious Studies 46 (2010), 353-373). Prima facie there is good empirical evidence that there is no God. In which case, the above suggestion looks to be no less an obstacle to the use of the Presuppositions Move with respect to religious miracles. So, prior to employing the Move, those theists insisting on the above disanalogy will need to come up with an adequate solution to the evidential problem of evil (a solution not dependent on the truth of religious miracle claims) – not an easy task.


So, my suggestion is that P1 is, prima facie, a fairly plausible principle – a principle that is applicable to the testimony concerning the miracles of Jesus. Note that P1 at least allows for the possibility that we might reasonably suppose a miracle has happened. Of course, I do not claim to have provided anything like proof of P1. But it does appear fairly accurately to reflect one of the ways in which we assess evidence. We do, rightly, set the evidential bar much higher for extraordinary claims than we do for more mundane claims.