Is formal logic really relevant for doing philosophy?

Yes. If you are bad at formal logic, the easiest kind, how do you think you can handle much more complex logic of metaphysics for example

>>9247657
It completely depends on what you're doing.
Most comtinentals don't use it (although pretty much all of them follow rehtoric rules in order to build solid arguments).

Studying formal logic helps you break down arguments and identify fallacies and debate better even if you're more interested in continental style philosophy. I think it is required at most schools for a philosophy major.

>>9247664
What metaphysics works rely on the knowledge of formal logic?
Genuine question, I've read some ontology but none of it relies on the rigid form of logical conclusions.

>>9247701
A lot of comtemporary analytics break down arguments into formal logic but it isn't inherently required, in fact it often tends to make arguments needlessly complicated. It's often the analytic variant of obscurantism.

Also, formal logic often doesn't even line up with "logical thinking". In fact most formal logic 101 that I had to take was just stupid exercises that had most students go "wtf, this is supposed to be logical"?

>>9248053
You are unironically a brainlet.

>>9247701
>What metaphysics works rely on the knowledge of formal logic?

modal metaphysics is a pretty clear example, for instance:

https://global.oup.com/academic/product/modal-logic-as-metaphysics-9780199552078?cc=us&lang=en&

>>9248067

Not that guy, but from logic one oh fucking one:

P -> Q

How the fuck is it logical that if P is false and Q is true, the implication is true? How the fuck does that make any god damn sense whatsoever.

>>9248067
KEEP M A T H OUT OF PHILOSOPHY

>>9248131
It's vacuously true. It is confusing at first but it makes sense when you consider that the truth of P is independent of the truth of Q.

This is where the English to describe the logic breaks down slightly. If P then Q isn't the best way to describe it, but the logical representation of the statement P->Q = notP or Q makes more sense.

Also an analogy like "if the moon is made of cheese, then I'm Jesus Christ" helps.

The statement is obviously false, so we cannot use that statement to figure out Q. Therefore Q is true by default because we cannot prove it's false given P.

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99KB, 798x798px

>>9248131
>failing to understand the relationship between necessary and sufficient
>philosophy major

>>9248131
Q doesn't matter if P is false. Think about it in terms of a promise, have I broken a promise when I promise Q if you do P, if you don't do P?

>>9248131
Because you're thinking in terms of causality, not in terms of material implication. What the truth table for material implication (i.e. "->") tells us is that if the whole proposition - P->Q - is true, then whenever Q is true, the whole proposition is true. And, in the case the whole proposition is false, then necessarily the antecedent is true and the consequent false.

The confusion in your head stems from the fact that you're thinking of material implications of, for example, a switch and a lightbulb. You're struggling with the fact that the lightbulb might be turned on independently of the switch (think of a lightbulb hardwired to be always on).

>>9248131
It also helps if you start thinking about mathematics (formal logic developed in the context of Cantorian set theory). One of the first proofs you'll end up learning is the one about the uniqueness of the empty set, and it employs this sort of false antecedent and true consequent reasoning. You can show it (that there is only one empty set) to be vacuously true.

>>9248131

you are trying too hard to translate the material conditional into the english "if...then..."

the material conditional is just a truth function, and it's more useful to have a truth function that is always true when the antecedent is false. (if you make the conditional false when the antecedent is false, it becomes equivalent to conjunction, and if you let it be true sometimes and false other times when the antecedent is false, then it feels arbitrary).

this doesn't show that formal logic doesn't line up with "logical thinking," what it shows is that first-order logic cannot perfectly translate all english expressions, which was obvious to everyone from the beginning and is why there are other, more expressive branches of formal logic