Conditional probabilities are reasonably effective because they are the mathematical underpinning of probabilities. They are not unreasonable effective. It's

Conditional probabilities are reasonably effective because they are the mathematical underpinning of probabilities. They are not unreasonable effective. It's just that sampling from probability distributions is computationally expensive, which has lead to the development of frequentist statistics (as opposed to Bayesian statistics). Frequentist statistics is unreasonably effective, since it makes so many assumptions that its hard to do a frequentist statistical analysis without violating some of the assumptions the methods have with regards to the data distributions, etc.