Classical Theism, Philosophy, and Religion Forum / Retorsion argument, first principles and non-classical logic

**Posted by Ouros** 4/04/2018 7:58 am

The basis of metaphysics, first principles, can only be defended with retorsion argument, or it seems so.

Now, given the advance of non-classical logic, where the law of excluded-middle or the law of non-contradiction can, at least that's what their proponents claims, be rejected on a certain domain.

*Does it mean that retorsion argument doesn't work? In any case, what does it imply for general metaphysics?
If retorsion argument can't be used, then it seems we can't neither use first principles without begging the question.
*Or maybe I'm wrong, and that would just means that metaphysics principles are faillible; but then, again, we couldn't uses them without appealing to intuition, which is close to begging the question.

**Posted by seigneur** 4/04/2018 8:40 am

Ouros wrote:
Now, given the advance of non-classical logic, where the law of excluded-middle or the law of non-contradiction can, at least that's what their proponents claims, be rejected on a certain domain.

Do you have an example?

**Posted by Ouros** 4/04/2018 8:44 am

Well, that's not my speciality, so that's why I asked, but I know that intuitionistic logic doesn't use the law of excluded-middle, and the dialetheistic view accept that there's true contradictions. Graham Priest is one who accept dialetheism for example.

**Posted by SapereAude** 4/04/2018 1:17 pm

Ouros wrote:
The basis of metaphysics, first principles, can only be defended with retorsion argument, or it seems so.

Too bad for metaphysics then.

**Posted by Ouros** 4/04/2018 2:04 pm

SapereAude wrote:
Ouros wrote:
The basis of metaphysics, first principles, can only be defended with retorsion argument, or it seems so.
Too bad for metaphysics then.

Well, I know what Kant and his successors had to say about that, but I don't think transcendantal idealism work, for three reasons:
1. Antinomies are solvable: If we apply first principle outside experience, ther's no contradiction.
2. Transcendental idealism presuppose, in fact, metaphysical principles as the PSR.
3. I think that we can probably, given 1. and 2., make a retorsion argument against the mere idea that first principles are only epistemically necessary.

**Posted by FrenchySkepticalCatholic** 4/04/2018 2:43 pm

SapereAude wrote:
Ouros wrote:
The basis of metaphysics, first principles, can only be defended with retorsion argument, or it seems so.
Too bad for metaphysics then.

Too bad for Kant, rather. Best use of his books, once read, is as a doorstop.

**Posted by DanielCC** 4/04/2018 3:14 pm

Kant although incredibly influential in terms of ethics is of comparatively little interest in theory of knowledge and even less in ontology.

With the best will in the world a lot of folks around here don’t seem familiar with contemporary philosophy. This applies also to deriving metaphysics straight from Aristotlean logic.

Although non-classical logic forms have some relevance to ontology and natural theology e.g. in giving one more amp against set theoretical problems and the Divine Liar paradox, it won’t gave the sort of foundation shaking effect some people seem to think. After all a lot of these logic systems were devised to get round annoying sceptical problems like the Liars Pararox.

**Posted by Ouros** 4/04/2018 3:30 pm

Well, I'm still a novice in philosophy. This is something I learn on my free-time, so I'm not afraid to say that I still need to learn a lot of things.

I know that non-classical logic was primary founded for semantic problems, but I don't think you really answered my question.
If I can rephrase it in more concise manner:
1) For doing metaphysics, your need to build from First Principles wich are certain.
2) For knowing what is a first principle, you need either intuition or retorsion.
3) Not intuition, because it's question begging for a skeptic.
4) Not retorsion, because even the most well-founded First-Principle, the Law of Non-Contradiction, is not certain in dialetheism.
5) Therefore, we can't do metaphysics.

What "premises" would you refute? And how?
I've vaguely read "The Aporetic Method and the Defense of Immodest Metaphysics" by Stephen Boutler, for example, but it seems to me that, ultimately, his method rests on intuition, because you'll need to fix something, and the skeptic could equally fix the opposite and adapt in consequence to keep what he already believe. No one could decide which one is right.

**Posted by DanielCC** 4/04/2018 3:42 pm

1,2 3, and 4. The point of intuition is in philosophy is that they give us a start off point e.g. a presumption in their favour, the sceptic might deny them or claim that their own intuitions differ must they have to do more than that to overthrow intuitive support.

I would disagree that ‘certainty’, if that should mean indubitablity, is obtainable in any sphere beyond a relatively narrow range of a priori truths. But certainty is not needed for knowledge only justification (so i don’t think it’s something the metaphysican should seek - if he or she wants to learn about epistemic foundationalism or coherentishm they should turn to phenomenology).

Epistemically the sceptic will be able to make various moves which force them to take increasingly outlandish and implausible postions. They will find though that the more of these moves they make the more they become committed to their own complex metaphysical position (think logical positivism which for all its anti-metaphysical rhetoric was a form of radical subjective idealism, complex with eliminatist approach to matter).

If some propositions can be both true and false presumably there is some criterion for this. Propositions like ‘I exist’, ‘X PSR holds’, ‘God exists’ or ‘Universals are Abstract Objects’ do not seem like the sort thing that could fall under this - what would it mean for instance to say the PSR is both true and false.

Last edited by DanielCC (4/04/2018 3:47 pm)

**Posted by Ouros** 4/04/2018 4:10 pm

But to say that they have to overthrow intuitive support assumes that intuition, or rather prima-facie "perception" is a good truth-tracking method in the first place. How would you even justify that?
Also, is it possible that the skeptic truly believe what he say, without deceiving himself? If so, how can that be the case, and how can we say which one, beetween him and you, is correct?

What would you propose as indubitable knowledge? If you say tautologies, it ultimately depends of the validity of the PNC, but its scope is, for you, a matter of subjectivity in the end, if I read you well:

DanielCC wrote:
If some propositions can be both true and false presumably there is some criterion for this. Propositions like ‘I exist’, ‘X PSR holds’, ‘God exists’ or ‘Universals are Abstract Objects’ do not seem like the sort thing that could fall under this - what would it mean for instance to say the PSR is both true and false.

That's a lot of questions. Sorry if it takes your time.