Which error is this?

[Goosebump]

The logical error is:
I'm not smart, but I am going to pretend I am.

Not sure why you would post this. It is my understanding that LadyforCamus is trying to get feedback on a question pertaining to a logical statement. I didn't reply cause I wasn't sure I could help. I found it more instructive to read and digest what other's chose to supply.

However your post doesn't seem connected to what is being asked or offered as answer. Rather it seems like a quip to seek attention. On that I am familiar with so thought I'd respond to you. I don't think your reply offers anything informative or funny. Others might find the humor. I found it childish.

[Fake Messiah]

I wasn’t exactly sure which sub forum to put this in. 

Which formal structural error is this? Is it still considered Affirming the Consequent if they’re using negations of p and q in the second premise?

I would say circular reasoning.

[The Valkyrie]

I wasn’t exactly sure which sub forum to put this in. 

Which formal structural error is this? Is it still considered Affirming the Consequent if they’re using negations of p and q in the second premise?

No idea.

When I get confused I fall back on my Catholic teachings and blame the Jews.

[Paleophyte]

Which formal structural error is this? Is it still considered Affirming the Consequent if they’re using negations of p and q in the second premise?

It's an unfounded premise.

1) If Thor does not exist then thunder does not exist. <--- Why assume that this is true?
2) Thunder exists.
3) Thor must exist.

That's entirely sound and a decent example of denying the consequent. If Thor is the only possible cause of thunder then the existence of thunder logically requires the existence of Thor.

But it depends entirely on the validity of P1. The instant that you introduce the possibility that thunder can exist without Thor then denying the consequent fails and the argument collapses.

1) If Thor does not exist then thunder might be caused by something else.
2) Thunder exists.
3) Thunder has an indeterminate cause and we can't say a bloody thing about Thor's involvement.

It's a lovely example of an argument that's logically sound but entirely unfounded. Which looks to have been the point of the person posting the obviously ridiculous Thor exists argument.

It's argument by assertion. Thor is the only possible source of thunder. God is the only possible source of morality. And that's arse backwards since they have to prove that god exists first before assigning him attributes.

[GrandizerII]

The argument is logically valid but not sound.

As this takes on the modus tollens form, there is nothing wrong with the structure. The problem is with the plausibility of P1, but that's a question of soundness, not validity.

Logically valid arguments are arguments in which the conclusion logically follows from the premises, regardless of whether the premises are true. The truth of the premises (if they are true, that is) guarantees the truth of the conclusion. I don't see how the conclusion fails to follow from the premises in this case. Once again, this is modus tollens in action (though you may need to rewrite the argument to see it more clearly).


Note to admins: This is Grandizer under a new account. Unable to access the previous one anymore due to lost email address. Please let me know if I'm violating the rules or not by posting under this account instead.

[Paleophyte]

Here's a well-founded version of the same argument so you can see that the logic actually works:

1) If water does not exist then fish cannot exist. (Well founded P1 because fish obviously require water to survive)
2) Fish exist.
3) Therefor water must exist.

[Angrboda]

The logic is valid -- the contrapositive of a true statement is also a true statement -- but the syllogism is unsound because not all the premises are true.

e.g.

1) If God does not exist, moral knowledge does not exist;
2) The contrapositive is also true, therefore, if moral knowledge exists, then God exists;
3) Moral knowledge exists:
C) Therefore God exists.

That's valid, but because #1 isn't true, the conclusion isn't valid.

[LadyForCamus]

Which formal structural error is this? Is it still considered Affirming the Consequent if they’re using negations of p and q in the second premise?

It's an unfounded premise.

1) If Thor does not exist then thunder does not exist. <--- Why assume that this is true?
2) Thunder exists.
3) Thor must exist.

That's entirely sound and a decent example of denying the consequent. If Thor is the only possible cause of thunder then the existence of thunder logically requires the existence of Thor.

But it depends entirely on the validity of P1. The instant that you introduce the possibility that thunder can exist without Thor then denying the consequent fails and the argument collapses.

1) If Thor does not exist then thunder might be caused by something else.
2) Thunder exists.
3) Thunder has an indeterminate cause and we can't say a bloody thing about Thor's involvement.

It's a lovely example of an argument that's logically sound but entirely unfounded. Which looks to have been the point of the person posting the obviously ridiculous Thor exists argument.

It's argument by assertion. Thor is the only possible source of thunder. God is the only possible source of morality. And that's arse backwards since they have to prove that god exists first before assigning him attributes.

I thought a formal argument was sound if and only if the structure is valid and all the premises are true? If we assume for the sake of the argument that P1 and P2 are true, then like you said, that doesn’t necessarily lead to a true conclusion. Doesn’t that mean, by definition, the argument is invalid? Not trying to be a pest here, just trying to learn.

[LadyForCamus]

The argument is logically valid but not sound.

As this takes on the modus tollens form, there is nothing wrong with the structure. The problem is with the plausibility of P1, but that's a question of soundness, not validity.

Logically valid arguments are arguments in which the conclusion logically follows from the premises, regardless of whether the premises are true. The truth of the premises (if they are true, that is) guarantees the truth of the conclusion. I don't see how the conclusion fails to follow from the premises in this case. Once again, this is modus tollens in action (though you may need to rewrite the argument to see it more clearly).


Note to admins: This is Grandizer under a new account. Unable to access the previous one anymore due to lost email address. Please let me know if I'm violating the rules or not by posting under this account instead.

Yes, I see it now! Thank you, Grand, and glad to have you back with us!

[LadyForCamus]

Thank you my lovelies! ❤️