This month one of the theist/atheist dialogs on the web is considering the topic of proof. Looking at peoples' responses to various proofs, the most striking effect of "proof" in the real world is often peoples' response to it: denial. There is no such thing as logic or proof "compelling" people to believe anything at all; people on any side of any conceivable disagreement can vouch for that.
Arguments that Infinitely Regress
In the case of "proof" when relating to the things of God, one common maneuver is "extraordinary claims require extraordinary proof", which is simply a detour onto what is necessarily an infinitely regressing argument. If a claim is labeled "extraordinary" then the proof must be extraordinary; but then that extraordinary proof itself becomes a claim which in turn requires extraordinary proof of its own, and the cycle continues. Notice that both ways out of this infinitely regressing argument are effectively blocked: if the next claim in the chain is "extraordinary" then the argument continues with need for further extraordinary support of the new claim; if the next claim in the chain is ordinary then, no matter how plausible, well-supported, and obvious it is, it can be swept away with simply not being "extraordinary" enough. The "extraordinary proof" method is therefore impossible to satisfy, leading either to a further extraordinary claim (in which case further regress) or to an ordinary claim (in which case the disputer simply asserts victory and dissatisfaction no matter how strong the plain old ordinary evidence). The "extraordinary proof" request is therefore inherently impossible to satisfy. It amounts to saying "I will not accept any argument for something extraordinary." Is it really logical that nothing extraordinary should ever happen, or should only be accepted on the basis of an infinite chain of extraordinary support?
Many of us do not actually see the claim of God's existence as anything extraordinary, given how obvious it is that there is a first cause and how likely it is, given the results, that the first cause is purposeful and intelligent. It is likely enough that everything you see about you in the natural world every day is proof of God's existence.
But, other than that, how exactly would someone prove that God exists? For that, God's intervention would count -- maybe some miracles. Not just "lucky" things, but the blind being healed, the lame walking, the deaf hearing. There are lots of miracles in the historical record, some with plenty of witnesses around. But those are extraordinary ...
But what if we wanted to know not just that God existed, but wanted to know God's mind? Even Einstein famously longed to know the mind of God. What if we wanted to hear him talk and see how he would approach life among us? For that, God could manifest himself among us, even incarnate among us if he chose to. Obviously Christianity claims that, in Jesus, God has done just that. To back up that extraordinary claim of who Jesus is, there is much extraordinary proof, more miracles than for any other religious figure in the history of the world including Moses and Elijah, and a proof unrivalled by any religious leader before or since: his own resurrection from the dead. But, then again, that's extraordinary ...
Of course, if God were to do something to catch our attention it would have to be extraordinary. It's no use complaining that we asked for something extraordinary but now that it's happened we won't believe it because it's extraordinary.
The Slippery Slope Is Actually A Big Bluff
The most common argument I have heard against believing that Jesus actually did the things his followers -- and enemies (see the Talmud) -- said that he did is that it is a "slippery slope". Oh what other things we would have to believe based on that level of proof! The worldview would disintegrate into incoherence and superstition! Actually, it would not. I would like to challenge someone to bring forward a claim that I would have to accept on the same grounds as accepting Jesus' miracles and resurrection:
- multiple eyewitnesses with their identities known and recorded;
- multiple same-century documents discussing the events in letters and biography (or "hagiography" if you prefer);
- along with the identities of witnesses, extended descriptions of the events in question with details of events;
- corroborating information from hostile sources (comparable to the Talmuld's references to Jesus as a sorcerer);
- persistent belief in the reality of the event amongst a significant number of witnesses;
- next-generation documents stating that the witnesses of certain events and the beneficiaries of miracles had survived to their own day and related the same accounts;
- and the extraordinary events having changed their lives so much that they devoted their entire lives to it, to the point of death.
The point? There is no slippery slope. It is very easy to believe the early Christian accounts of extraordinary things based on their incomparably high level of plain historical support for these extraordinary things. Such a belief does not lead irrevocably down some slippery slope to superstition. That argument is a bluff. Unless someone can meet the criteria above, I'd say that I'd called the bluff.
The Proof Is In
Jesus' empty tomb is God's proof to us that our own tombs will be empty on the last day. But what proof is ever undeniable? It is one thing to say that the mere fact that "it is possible to deny it" provides a ledge to stand on; it is another thing to say that that is a good position that results from good logic.