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

[The Grand Nudger]

Classical examples of causality arise because macroscopic things are made of a LOT of quantum level things. The *averages* of the probabilities have a deterministic, even Newtonian, structure. The fact that Avagadro's number is big is why we can even talk about causality at the macroscopic level.

I don't see philosophers grappling with this basic set of facts. Instead, they seem to think that causality is an a priori truth that *must* hold for science to be done. But that is clearly wrong.

Instead of causality upholding the laws of physics, we now see that the laws of physics *allow* for causality in some circumstances.

The answer to why philosophy historically did that is nestled in the question.  Up until the point that it was discovered that the underlying physics may be fundamentally acausal, another idea was better evidenced.  Not so much anymore, which is why it's easy to find find contemporary philosophers discussing things that philosophers from a century or more ago did not.

And so what else is required above consistency? You cannot determine the truth of falsity of a consistent statement by simply sitting and thinking about it. At some point, you *need* to do some sort of observation. That is why some empiricism is required. It is an additional filter to weed out falsehoods. And it does this incredibly well, as witnessed by the advances of science once it became prominent.

Valid inferences and sound premises.  Empiricism has been helping with sound premises since before there was a thing called science. The only things you can know by consistency are issues of definition. A married bachelor is incoherent, so is an incompetent omnipotence.

Yes, this is required to 'live the good life'.

And, if philosophy limited itself to such *opinions* that can vary from person to person because of differences in personality, it would maximize its value.

Again, the main value of philosophy is in *asking questions* and *challenging assumptions*, not in finding truth or knowledge. When it comes up with grand over-reaching theories, it tends to fall on its face.

The entire concept of knowledge and truth are both philosophy.  We call a conclusion derived from sound premises in a valid inference "true".  That's all that means. That's all an objective statement is, in any context, even ethical and aesthetic contexts. We think that the true positions we hold are "knowledge". Thus, moral knowledge, or knowledge of beauty, or the rich tapestry of symbolism. All that jazz. You've been thoroughly steeped in a philosopy about ethics, too, and believe it's true, that it's knowledge - that's what's informing your objections and the specific language of those objections. Realist philosophies are uninterested in opinions, though, and the ethical theory you're expounding here is as out of date as classical mechanics.

The trouble with your position here, is that you have neither a sound premise nor any voiced rationale for declaring all x opinion - and these two mistakes are propping up an unspoken value system which you purport to report as a fact. It's a snake eating it's own tail kind of mistake. This, no matter how many examples you're presented with that speak to each concern directly.