[Serious] Generally speaking, is philosophy a worthwhile subject of study?

[vulcanlogician]

Well, I can point to Kant who said that Euclidean geometry is synthetic a priori knowledge. Then non-Euclidean geometry came along.

Or Aristotle who claimed that any type of 'motion' (which , in his context meant any change) required a force or a cause. Then Newtonian physics came along where uniform motion is natural and needs no cause.

Or I can point to Aquinas, who spent an inordinate amount of time trying to figure out how angels can move based on Aristotelian physics.

Good criticisms of Kant, Aristotle and Aquinas. But weren't we trying to criticize philosophy in general?

I'm not even sure I agree that philosophy is a good source of theories any longer. it was until the rise of science, I agree, but for the last 200 years or so, I have seen no philosophers add to the list of testable theories. Kant's proposal of an 'island universe' (which we know of as our galaxy) was perhaps the last good contribution from a philosopher. Certainly there has been nothing offered since the rise of modern science that has actually impacted science at all.

In philosophy, we have theories like logical positivism that express the things you are saying. If you want to defend logical positivism, you can do so within philosophy. I'm not saying that's what you ought to do; maybe that's not your cup of tea, polymath-- and that's fine. But if you thought a good defense for logical positivism or radical empiricism could be made, and you felt like making one, philosophers are the ones who are interested in what you have to say. If you're correct in your assumptions and logic, we're the ones who care that you're correct.

Logical positivism and radical empiricism are supported by strong arguments. IMO, they survive the kitchen sink test. Great theories. Very solid positions. Most contemporary philosophers acknowledge this. Even detractors are careful to say how strong and reliable empirical observation is. If someone is an ardent Aristotelian, that's not philosophy's problem. That's their problem. Philosophy is just as determined as you are to refute Aristotelianism, perhaps even more so.

You can't just say philosophy is always wrong, citing "those damned Aristotelians," without also acknowledging how many philosophers agree with your assessment of Aristotle. "Aristotle is wrong" is quite a good way to begin a philosophy paper nowadays.