What you describe here is as compatible with realism as antirealism.If something exists then it is possible to know that it exists, and if it is doing something then it is possible to know that it is doing that thing, and if it is not doing something then it is possible to know that it is not doing that thing, and if it doesn't exist then it is possible to know that it doesn't exist – with the same reasoning applied to the past, the future, and counterfactuals. — Michael
Generic Realism:
a, b, and c and so on exist, and the fact that they exist and have properties such as F-ness, G-ness, and H-ness is (apart from mundane empirical dependencies of the sort sometimes encountered in everyday life) independent of anyone’s beliefs, linguistic practices, conceptual schemes, and so on. — SEP Realism
...realism holds that ...stuff... is independent of what we say about it; anti-realism, that it isn't. — Banno
So a theist might attempt to adopt a modified Tarski, such that "p" is true IFF p is willed by god. It might be more honourable if @Leontiskos came out with this openly.Being a theist he could say that the cat is on the mat is true because God is there to judge it to be so. I guess we can say that truth is a property of judgements, if a judgement would qualify as a a kind of proposition, although that question would open up some other issues I suppose. — Janus
There is a relevance argument against BIV. You take Realism ⊨ ◇BIV, which i thinks is overreach. I say Realism → (BIV v ~BIV), and for independent reasons ~BIV. — Banno
This general characterization of metaphysical realism is enough to provide a target for the Brains in a Vat argument. For there is a good argument to the effect that if metaphysical realism is true, then global skepticism is also true, that is, it is possible that all of our referential beliefs about the world are false. As Thomas Nagel puts it, “realism makes skepticism intelligible,” (1986, 73) because once we open the gap between truth and epistemology, we must countenance the possibility that all of our beliefs, no matter how well justified, nevertheless fail to accurately depict the world as it really is. [See Fallibilism.] Donald Davidson also emphasizes this aspect of metaphysical realism: “metaphysical realism is skepticism in one of its traditional garbs. It asks: why couldn’t all my beliefs hang together and yet be comprehensively false about the actual world?” (1986, 309)
◇Kp does entail p. — Banno
Another, again separate, point is that if p ⊭ (q ∧ ¬Kq) then p ⊨ (p→(q→Kq)). If p doesn't entail that there is something we don't know, then it entails that we know everything. — Banno
What you describe here is as compatible with realism as antirealism. — Banno
But then maybe we need to distinguish between two types of realism; one that denies phenomenalism/idealism and one that denies the (restricted) knowability principle. Labels notwithstanding, Devitt's "realism" might be consistent with Dummett's "anti-realism". — Michael
...realism holds that ...stuff... is independent of what we say about it; anti-realism, that it isn't. — Banno
Yep. You repeat stuff I've already addressed. Only a certain interpretation of realism implies that BIV is possible. That interpretation is not the only one. This is set out in the first half of the paragraph you cite.Assuming the law of excluded middle, BIV ∨ ¬BIV is a truism, and is true even if ¬◇BIV. Realism entails more than this, as explained in the IEP article: — Michael
One proposal is to construe metaphysical realism as the position that there are no a priori epistemically derived constraints on reality (Gaifman, 1993). By stating the thesis negatively, the realist sidesteps the thorny problems concerning correspondence or a “ready made” world, and shifts the burden of proof on the challenger to refute the thesis. One virtue of this construal is that it defines metaphysical realism at a sufficient level of generality to apply to all philosophers who currently espouse metaphysical realism. For Putnam’s metaphysical realist will also agree that truth and reality cannot be subject to “epistemically derived constraints.” This general characterization...
Not at all. ~p→~◇Kp ↔︎ ◇Kp → p. If something is not true then it is not possible to know it is true; hence if it is possible to know something then it is true.No it doesn't, just as ◇p does not entail p. Despite me literally telling you not to, you appear to have confused ¬p ∧ ◇Kp with ◇(¬p ∧ Kp). — Michael
Again, I'm suggesting that the choice between applying realist and antirealist logics is context-dependent. So I do not agree that "every meaningful declarative sentence is either true or false" and hence I do not agree that counterfactuals must be either true or false. (Edit: however, I am happy to take "if Hitler hadn't killed himself then he would have been assassinated" as false. He might have been hit by some random artillery fire.)Semantic realism... — Michael
No. Realism is applicable when "a, b, and c and so on exist, and the fact that they exist and have properties such as F-ness, G-ness, and H-ness is independent of anyone’s beliefs, linguistic practices, conceptual schemes, and so on", and to this list we can add knowledge. In cases where truth is dependent on anyone’s beliefs, linguistic practices, conceptual schemes, or knowledge, then antirealism might be applicable.If you are suggesting that anti-realism is arguing the latter... — Michael
Or to phrase this differently, it is possible, logically speaking, that your are indeed a vat brain - Putnam's argument fails to show otherwise. — Banno
If something is not true then it is not possible to know it is true; hence if it is possible to know something then it is true. — Banno
Again, I'm suggesting that the choice between applying realist and antirealist logics is context-dependent. So I do not agree that "every meaningful declarative sentence is either true or false" and hence I do not agree that counterfactuals must be either true or false. — Banno
No. Realism is applicable when "a, b, and c and so on exist, and the fact that they exist and have properties such as F-ness, G-ness, and H-ness is independent of anyone’s beliefs, linguistic practices, conceptual schemes, and so on", and to this list we can add knowledge. In cases where truth is dependent on anyone’s beliefs, linguistic practices, conceptual schemes, or knowledge, then antirealism might be applicable. — Banno
Are you saying this is invalid? I don't think so.This is not how modal possibility works. — Michael
~p→~◇Kp ↔︎ ◇Kp → p. — Banno
◇Kp means ◇(p ∧ JBp), where JBp means that p is justifiably believed. ◇(p ∧ JBp) does not entail p and so ◇Kp does not entail p. — Michael
No. Context.So you're an anti-realist about counterfactuals? — Michael
This somewhat begs the question, since of course the antirealist wants the commonplace, that there are things we don't know, to be true. The issue here is how to formulate antirealism so that it is constant with there being things we don't know.The antirealist allows for p ∧ ¬Kp, regardless of what Fitch might think. — Michael
Are you saying this is invalid? — Banno
The issue here is how to formulate antirealism so that it is constant with there being things we don't know. — Banno
The intuitionistic anti-realist takes solace in the fact that she is not committed to the blatantly absurd claim that all truths are known.
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Notice that T-knowability is free of the paradoxes that we have discussed. It is free of Fitch’s paradox and the related undecidedness paradox.
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Dummett’s knowability principle or DKP, like Tennant’s, is not threatened by the knowability paradoxes, and for the same reason.
you think realism inconsistent in all cases? — Banno
Well, yes, that's kinda the point.¬p ⊬ □¬(p ∧ JBp) — Michael
Yep. With the consequences set out in the SEP article:That's been done. — Michael
The debates surrounding the proper characterization of semantic anti-realism go far beyond the scope of this entry. As for the knowability proof itself, there continues to be no consensus on whether and where it goes wrong.
Some do. Good for them. The question of whether they are right remains open.The antirealist claims that there are unknown truths but that all unknown truths of the appropriate kind1 are knowable. With respect to ontology, there are unverified truths but there are no verification-transcendent truth conditions. — Michael
That, Michael, remains an open question. You misrepresent my position. Again, I am suggesting that different logics might have application in different contexts; that we can adopt a realist approach in some circumstances and an antirealist approach in other circumstances; that it is not all-or-nothing.it neither claims nor entails that all truths are known — Michael
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