Quick question: Does anyone know of a formal from-first-principles justification for Occam's Razor (assigning prior probabilities in inverse proportion to the length of the model in universal description language)? Because I can't find one, and frankly, if you can't prove something, it's probably not true. I'd rather not base my entire thought process on things that probably aren't true.

I suspect you will never find one. To get the scientific process off the ground you have to start with the linked assumptions "the universe is lawful" and "simpler explanations are preferable to more complex ones". Those are more like mathematical axioms than positions based on evidence.

The reason being, you can explain absolutely any observation with an unboundedly large set of theories if you are allowed to assume that the laws of the universe change or that complex explanations are kosher. The only way to squeeze the search space down to a manageable size is to check the simplest theories first.

Fortunately it turns out we live in a universe where this is a very fruitful strategy.

ETA: I'm relatively new here: Whoever downvoted this could you perhaps explain your thinking?