A fallacy JUST IS an error in logic that makes an argument INVALID.
p ⇒ q
P
∴ q
is VALID, regardless of values of p and.
p ⇒ q
q
∴ p
is INVALID, regardless of values of p and q.
2 This glass contains water
3 ∴ this glass contains H₂O
1 Water is HCl
2 This glass contains water
3 ∴ this glass contains HCl
are both VALID. They are, in fact, the SAME ARGUMENT FORM, namely
1 A is B
2 C contains A
3 So C contains B
A logical fallacy just is a logical error that makes an argument INVALID.
Changing the terms LITERALLY CANNOT HAVE ANY EFFECT on an argument’s validity.