>>12928728If you don't believe in probability, then you just have to recognize that probability models long-run proportions of an event. For example, a coin flip will ultimately end up evenly split, so the probability is 0.5
For the sciences (and even social sciences), which deal with the general case, probability provides a very quick and easy form of measurement. Obviously, it's not necessary if you can determine a causal relationship, but that's just conditioning (and thus part of probability).