Inverse Probability and the Argument from Design
When we look at the universe with the laws of governance that give some structure it’s possible to wonder if this structure is the result of design undertaken by some power of some sort that could be described as a type of god.
We have a premise – P – that the universe shows a sort of design. And we have a conclusion – C – that asserts the existence of a creator.
What this means is that unless C is true, P is unlikely, and in the case of P, C seems likely.
But what we really need to do in order to discover if P is a strong inductive reason for C, is to work out the probability that C, given P, is greater than its negation.
The high probability of P given C, does not mean there’s a high probability of C, given P.
We’re talking about inverse probabilities and if the Argument from Design is to function, the probability of C given P must be higher than its negation.
Before we go on, let’s look at a simple example. Say for instance we are trying to work out which day of the year it is. Let’s say we think it might be the 164th day of the year. What are the chances this is correct? The chances are much higher it is any one of the other possible 365 days of the year.
Taking this example to the Argument from Design we can see there are many different ways the universe could have been – some might have had a law of gravity that repelled for instance. The possibilities of different applications and reversals of laws known and unknown are endless. These disordered universal possibilities allow us to say the level of order we see is a special property but all those other possibilities suggest there are relatively few universes in which there is likely to be a creator. Not all possible universes are special and creators must be more special still.
This suggest a priori, that C is far less likely than it is likely. The Argument From Design fails and its subscribers can be said to be confusing probabilities with inverse probabilities.
Acknowledgment: Graham Priest.
"Experiments are the only means of knowledge at our disposal. The rest is poetry, imagination." Max Planck