I understand that it was Cavendish, not Lavoisier, who first identified water as a compound (through experiments around 1781), though Lavoisier's chemical revolution helped fix the conceptual framework. — Banno
Yes, I stand corrected.
It occurred to me on looking again that there are two readings of what you wrote - the de re and the de dicto. The sentence ‘Water is H₂O’ was not something people could assert or know before Cavendish; the term "water" did not yet rigidly refer to H₂O. So if you were saying that the word "water" could not be used to refer to H₂O before Cavendish announced his work, I agree. — Banno
Yes! Bingo!
de dicto is what I mean --
However, if the assertion is that prior to Cavendish's announcement, the chemical structure of water was not H₂O, it is I think in error. — Banno
There's a sense in which we can entertain the idea that matter itself changed, but I think it's an erroneous inference -- even if it were true there'd be no way for us to make that inference because we don't live in that time. We live in now. And what seems most consistent is that nature hasn't changed all that very much from then to now, in the sense that there are fewer hoops to jump through mentally to make an inference.
Note, though, that none of this is scientific. It'd be impossible to determine, scientifically, if the meaning of "water" in Aristotle's time
excluded H2O as a possibility, which is where I think the sympathetic readings of Aristotle get headway: broadly accepting an Aristotelian framework while changing the details to match what we know now in a scientific spirit.
For myself I'd say that Aristotle is not a scientist in the modern sense -- this isn't to speak against his work as a scholar, only to note that first guesses will often be inadequate, even if they hold a certain spell to them. What's atractive in Aristotle is how it all seems to fit together into a harmonious whole -- but this is a siren's song more than a mark of wisdom, if you ask me.
It's entrancing, but doesn't really look like the world I see now. And I'm not sure how the methods of metaphysics in Aristotle are somehow better than latter methods of metaphysics -- it seems to me that this is very much in the realm of philosophy and philosophy alone, where the science is a grab-bag for examples of reflection, but not philosophy itself.
This to go back to my point with
@Richard B -- that philosophy is not using science to give itself credibility, and it has no need to do so.
There's all sorts of complexities here. The foremost is that Kripke's "Water=H₂O" is intended only for extensional contexts. While Aristotle presumably believed fish live water, he doubtless did not believe that they live in H₂O.
We should head back to the topic at hand, which is "what is real". The idea seems to be that there is an essence, a "what makes a thing what it is", and that this is of use in deciding what is real and what isn't. Along with this goes the view that there really is a difference between what is real and what is not real, such that for any x, the question "is x real" has a firm "yes" or no"no" answer.
I think that view is mistaken, for reasons I gave earlier. And I think that view is quite common amongst philosophers - at least those who are alive. — Banno
We're in agreement here, for the most part and for what's worthwhile in the thread as points of contention.
there's a grab-bag of entities which don't have as firm an answer as we'd like -- dreams, halucinations, mistaken worldviews, historical counter-factuals, hypothetical examples...
We could certainly stipulate answers, though I tend to think "X is real" sounds like "X exists", and I'm still fairly well persuaded by Kant on that -- that there is no difference between the imagined unicorn and the real unicorn in terms of its predicates. The old "existence is not a predicate" thing, which isn't strictly true but it gets at something important about making inferences about existence -- in a lot of ways we treat reality like it's given. If whatever we conceptually designate as "the given" matches our conceptions of "the given" then we are inclined to say such and such exists.
Or to go along with Quine -- to be is to be the value of a variable. So it's not a predicate, but a quantifier over predicates. (EDIT: Or individuals? "Over" loosely meant)
Both seem to handle inferences about existence better than positing an essence, to my mind. Which part of water are we to call its essential part, after all? As you note, in Aristotle, the essential part was
not that it is H2O. So why the switch? What makes this description a better example of essence, or is it at all?
But here are those amongst us who, bathing in the light of Plato and Aristotle, seek to reinvigorate metaphysics by bringing back the "what makes a thing what it is" version of essence. And that's pretty much were the argument here stands. — Banno
Funnily enough I kind of welcome the resurgence, as long as we take the historical approach. They really do have valuable things to offer a thinking mind, and points of comparison between ancient and modern science are deeply illuminating on the practice of producing knowledge.
It's their difference that I value, above all. I don't care of its true!
:D
I'll leave this now, although I might come back to it and talk about water again.
Cheers.
Cheers!