The Watchmaker: my fav argument

[Angrboda]

It would be more accurate to say that in science we go for the simplest (without any elements not required) explanation that accounts for all the observations. Saying God did it is functionally equivalent to saying 'magic did it' and doesn't actually explain anything.

I don't know how true that is of science. Yes, ideally you want a particular model to be as economic as possible. But you never choose between models based on simplicity. (At least that hasn't been the case in the cognitive sciences; our theories seem to get more complex over time.)

Theories are tools for scientists, so perhaps in that sense they might opt for the lightest hammer. But simplicity isn't a replacement for experimentation. And I'd be interested to see an example where simplicity actually did what you say it does.

Edit: And if I may add: Given that you have no access to reality, except by your theories, you have no contrast by which to measure simplicity. In other words, you are unjustifiably deciding that a given level of simplicity is correct. But the more complex theory could be the simplest, and the one you've chosen an oversimplification. Simplicity is an unjustified preference, that reflects the limits of our brains, rather than the nature of reality.

I think you may be talking past each other. As I pointed out earlier, simplicity is only preferred if the simpler explanation accounts for all the facts. I think this is more of a heuristic than an infallible guide. However, I will point out that a more complex explanation has more parts, by definition, and more parts means more terms added to the probability equation that have to be correct for the explanations particulars to be true. That doesn't necessarily mean that adding those terms lowers the overall probability below that of the alternative, but in the general case it does. This goes double if the terms employ the principle of sufficient reason. As a result, most times the simpler explanation will be more probable simply because of its lack of complexity. That doesn't mean it is necessarily the case that the simpler explanation is correct, but if a man proportions his belief according to the evidence, it is generally not rational to prefer the complex explanation.