ok, so scientifically speaking “proof” is a mathematical concept only, physics doesn’t prove shit, chemistry doesn’t prove shit, no other science proves shit.

But economics, like every other science out there makes models, these models when applied to certain circumstances make predictions, we test these models by testing the predictions they make.

The more accurate the prediction the better and more relevant the model, the issue that economics has is that many people instead of looking at the actual science, take the fictional work and claim it reality, mainly because they believe some propaganda commissioned by really wealthy people, to keep their wealth. the Laffer curve is one such example because it allows rich people to invest into lower taxes and increased privatization.

The Laffer curve isn’t bad because Regan used it, it’s bad because it has a track record of not having any predictive capability.

Also, there exist mechanisms by what we punish tax evasion, taking the likelihood of tax evasion into account for the purpose of setting tax rates is self-defeating, in the assumption that any persons want the maximum amount of money for themselves would always try to evade taxes, no mater what the tax rate is.