The short answer is yes and no. Pythagoras’ belief system often overpowered his science, yet his empirical observations stood the test of time. This makes him a rational pragmatist—someone who accepts empirical truths but also accommodates personal beliefs, sometimes at the cost of reason. Unfortunately for his reputation, many of his personal beliefs were wrong.
The longer answer is that Pythagoras is a fascinating case study in both sound and flawed thinking as well as an interesting use case of pragmatism as defined in chapter 22 of 30 Philosophers. For my new look at pragmatism, there are three types: empirical, rational, and irrational. An empirical pragmatist is someone like me. Someone who is trying to live their life believing in no irrational ideas. In general, I believe in common things until proven wrong, but I also pay close attention to questioning everything, and like any skeptic, I keep an open mind to evaluating ideas.
Unlike empirical pragmatists, rational pragmatists like Pythagoras mix sound reasoning with personal beliefs. Some of those beliefs, like the divine nature of numbers, didn’t stand up to scrutiny. Most people are rational pragmatists. They believe in common knowledge but also hold onto the family’s religious beliefs. Most of my friends, and most people I know, are rational pragmatists, which mostly aligns with common knowledge, but they embrace things in support of their spirituality and specific religion. Beyond that, they are generally cautious about adopting ideas that lack evidence.
In contrast to both, the irrational pragmatist rejects even common truths, dismissing evidence outright. They frequently say things like “there is no such thing as truth.”