Question on validity of arguements

mzoodle

If the conclusion does not HAVE to be true, then the argument is invalid?

TheAnxious0L

Not necessarily.... could you explain a little bite more what you mean by that though?

Validity and truth are not the same, but before I dive into that, please clarify what you mean

kcb77-1

Hey, I'd like to take a swing at this one. Beshir, Let me know what you think.

Essentially, all premises could be false and yet an argument could be valid if and only if the conclusion follows logically, i.e.,

Superman never flies in the comics.
If someone never flies in the comics, then they are an accountant.
Therefore, Superman is an accountant.

Although the premises are false, the argument itself is valid since it can be inferred from the premises that Superman is indeed a farmer. Conversely, a conclusion which states that if one is an accountant then he/she is Superman is invalid since that statement does not follow from the stated premises. If a conclusion is stated which cannot be supported from the given premise(s), then that argument is logically invalid and some assumption(s) underlies it. Additionally, if an argument proffers a conclusion which is indeed in and of itself a statement which is known to true but does not follow from the premise(s) offered in support of it, then, taken together, the argument is invalid.

To reiterate and expand a little: you asked,
"If the conclusion does not HAVE to be true, then the argument is invalid?"
The short answer is yes if you're asking whether the conclusion MUST be true on the basis of the premise(s). Again, if the conclusion does not HAVE to be true on the basis of the premise(s) given in support of it, e.g., if the conclusion is not entailed/cannot be inferred from the premise(s), then the argument is invalid.

Cant Get Right

@"kcb77-1" said:
Essentially, all premises could be false and yet an argument could be valid if and only if the conclusion follows logically, i.e.,

Superman never flies in the comics.
If someone never flies in the comics, then they are an accountant.
Therefore, Superman is an accountant.

Although the premises are false, the argument itself is valid

Correct. Validity has nothing to do with truth--only logical structure. A valid argument is logically perfect and the conclusion cannot not follow. An invalid argument is anything else: Any argument at all shy of logical perfection is entirely invalid.

As far as truth goes, validity does not imply a truth value. That is soundness. A sound argument is a valid argument with all true premises. An unsound argument is any argument that is either invalid or contains an untrue premise. We don't deal with soundness on the LSAT; we presuppose the truth of any premise we're given.

kcb77-1

Correction: "Although the premises are false, the argument itself is valid since it can be inferred from the premises that Superman is indeed AN ACCOUNTANT"....

And thanks for adding the bit about soundness Cant Get Right*