10 June 2006

Leaps of faith

There’s been some discussion on the Dilbert Blog about whether sceptics and believers require the same leap of faith. For example, here's a comment from Omar:
It does require faith to believe in both the existence AND non existence of God. And by faith here, I mean a leap from the place were the evidence ends, to the place where you draw the conclusion.

I think that there IS an important difference here. Basically, claiming that God does not exist is inductive, whereas it may be argued that claiming that God does exist involves a leap of faith. Let’s have some explanation of a couple of terms before we go on.

Deductive means that the conclusion of an argument is necessitated by the premises, as in the typical syllogism:

  • All men are mortal;
  • Socrates is a man;
  • therefore
  • Socrates is mortal.

Induction is an argument in which the premises of support the conclusion but do not ensure it, such as:

  • All observed crows are black;
  • therefore
  • All crows are black.

Generally, a careful sceptic will make an inductive argument about the existence of God, something like this:

  • No evidence of the existence of God has been observed;
  • therefore
  • God does not exist.

Note that this is not a deductive proof of the non-existence of God. It does not exclude the possibility of some future proof, but it does take current evidence and base a generalisation on it. The typical response of a modern Christian believer is that belief in God does not require proof, but faith, and no amount of ‘missing’ evidence can disprove anything, let alone God. These two positions can coexist with little more trouble than the usual tension between believer and non-believer: on the basis of the lack of evidence the sceptic sees no reasonable grounds to believe, while the believer claims that ‘reasonable grounds’ are not the point.

Less sophisticated believers and sceptics will make more ‘aggressive’ statements which have absolutely no validity, such as saying that no proof of God constitutes a disproof, or that since there is no disproof, that constitutes some kind of proof. It would be wrong, however, to think that either of these positions require a ‘leap of faith’, since that would be synonymous with ‘faulty logic’ here. A ‘leap of faith’ happens elsewhere.

Going back to the more sophisticated positions, it may be true, as Omar suggests, that faith begins where evidence ends. An inductive argument about all crows being black may require faith in the sense that it assumes that all the non-observed crows will be similar to the observed crows. But one should be careful talking about ‘faith’ here, since the word has far wider religious connotations, and conflating faith based on evidence and faith based on belief would seriously muddy the waters of discussion.

The inductive argument cannot be said to require a ‘leap’ either, although we can still distinguish between strong and weak induction, an example of the latter being as follows:

  • I always hang pictures on nails;
  • therefore
  • All pictures hang from nails.

That may well involve a ‘leap’, but it is still based on evidence, and is as such inductive rather than faith-based.

The believer, on the other hand, makes a leap of faith because they believe regardless of the evidence. They may well describe their faith as precisely ignoring the lack of evidence, such as saying that God wants you to believe freely with an open heart, rather than requiring some qualified evidence-based belief.

Both positions may arguably be valid, but they do not require the same ‘faith’ or the same ‘leap’.

It might be, however, that a believer may base their belief on a different kind of evidence (the evidence of the heart, for want of a better way of expressing it). And if that is the case, then they might also claim that their belief does not require a leap of faith, because to them it is self-evident. Asking a sceptic to take their word for it and therefore to believe, would be asking the sceptic to make a leap of faith, which no sceptic would be prepared to do. In fact, rather than saying that both sceptics and believers have to make a leap of faith, I’d be tempted to argue that neither do.