Evidence Yes, But Evidence For What?

shoesDuring my catch-up reading I came across an observation made some time ago by Deacon Duncan at Evangelical Realism that got me thinking.

This is the old superstition vs. science dilemma, the fellow who says shoes are made by elves in a hollow tree, and then cites the existence of shoes as evidence that elves are real.

Phrased like that it is easy to see the error in the reasoning. Yes, shoes could be evidence of elves, but there are other, less fantastic, possibilities and we should consider these first. When the example is elves, most people will be willing to look critically at the claim and see through it. Those with a sense of irony and a knowledge of rhyming slang may even describe it as “Cobblers“!

Nevertheless, this kind of fallacy appears surprisingly regularly. For example, consider the patterns sometimes found in fields, known as crop circles. Often these can only be fully appreciated from the air and seem to describe the shape of some kind of complex craft. While some crop circles are created by people making no unusual claims about them, others are claimed as evidence of alien visitors. In my view it’s far more likely to be evidence of mischievous earthlings.

When a patient improves after having taken some previously untested treatment or medicine, is that evidence that the treatment is working or that their immune system is doing its job? In cases like these it can be hard to tell, so thorough clinical trials are needed, involving more than one patient, placebo controls, etc.

Similarly, the creationist website, allaboutcrreation.org makes this popular claim:

Where is the proof of God? If we’re willing to open our eyes, we’ll see the fingerprints of God all around us and all throughout us. Our very existence proves the existence of a Creator God.

270px-CropCircleWI’m sure most of us have seen religious people point to a beautiful flower and say, “There! That’s evidence that God exists!”. Again, this could be evidence of a great many things, including the symbiotic relationship between flowering plants and insects which are attracted by bright colours and floral scents. The fact that we as humans think that the flower is beautiful may be evidence that we are adapted to appreciate a fertile ecosystem and the fruits that it can bring.

Even the Bible has some of this kind of gargantuan jump, in reverse from what they are trying to establish – the existence of a god, to a piece of alleged evidence, as in Romans 1:20:

For since the creation of the world God’s invisible qualities–his eternal power and divine nature–have been clearly seen, being understood from what has been made, so that men are without excuse.

I think that verse could be rephrased to be clearer about the leap of logic it’s making. Anyone care to make a suggestion?

In all cases it seems we are in danger of leaping to a conclusion that is not necessarily the cause of the evidence we’re seeing. The solution is perhaps to imagine several possible causes and try to understand why we should prefer one over the others.