Best way of understanding validity?

TheAnxious0L

I'm really struggling with concepts of validity.... I've done the drills, but it's not making sense to me.

Looking for suggestions on how to best understand and apply validity to LR. Any suggestions on learning tips&tricks would be so helpful

Alex

@"Idil.Beshir" said:
I'm really struggling with concepts of validity.... I've done the drills, but it's not making sense to me.

Looking for suggestions on how to best understand and apply validity to LR. Any suggestions on learning tips&tricks would be so helpful

Hey happy to help!

I'm guessing you've seen the CC lesson on validity: https://7sage.com/lesson/validity/
Perhaps re read this lessons?

Could you articulate a little more what concepts of validity aren't exactly making sense?

A little summary that might help:

Truth is a property of sentences. Sentences are true or false. Sentences are not valid or invalid. Validity is a property of arguments. Arguments are valid or invalid.
As for validity, the definition basically comes down to that IF all the premises of the argument are true, when that’s the case, then the conclusion must also be true. This is generally what we refer to a "Valid" argument.

If all Cats are Orange
And Felix is a cat
Then Felix is Orange.

This is an example of a valid argument.

So just help me understand what you may not be understanding, because it might be something minor, and it can be hard concept to fully get.

Unfortunately, there really are not any tips and tricks for the most part with respect to validity and invalidity. I think it is just one of those things that you have to understand at their logical core before you can properly apply them to LR questions.

akistotle

Could you maybe elaborate on what you don't understand? If there are specific questions you did not understand, I would be happy to help

acsimon

On board with the query for elaboration on the confusion as well as Alex's explanation. I would only add that the validity relation between a set of sentences (i.e., premises) and a sentence (i.e., conclusion) is something that holds as a matter of the structures of those sentences and not their contents.

This is important to keep in mind, not only for the grasp of the concept in question, but also because it might be that there are arguments where the truth of the premises guarantee that of the case conclusion, but it is an invalid argument.

For example:

(1) All Tea contains water.

(2) All gasoline contains oxygen.

Therefore,

(3) All gasoline contains at least one of the same element as is contained in water.

Here, since water is H2O (actually, this is a matter of some controversy in Phil science) the truth of the premises guarentees the truth of the conclusion--true physical identities being neccessarily true. Still, the argument is clearly invalid from the point of view of formal logic since you can substitute in other sentences with exactly the same structures and generate an argument where the premises hold but the conclusion does not. What this makes clear is that the structure of the relevant sentences is what matters for the definition of validity, not their specific contents. This is why general truth preserving (valid) rules of inference can be defined at all (for ppl to memorize for the LSAT, in this case)--A.c.S

gioaragon95

*Video link bellow

I think it really comes down to the form and structure. As everyone has said above and given examples of this. Valid arguments have a logical structure, the form of the argument logically follows from the information given.

With practice and repetition of the valid and invalid argument forms. You can better see the flow and structure of an argument and determine quickly whether it is valid or invalid.

However, validity is different than truth. As you will see when going into flawed arguments, there might be some arguments that have a valid form, however, the truth of the arguments premises do not follow. In addition, you will see many invalid arguments which deal with mixing up sufficient and necessary conditions.

It really comes down to how logicians, philosophers, and those that analyze arguments read and understand an argument. It's sort of our structural language.

There are also tons of videos on Youtube about professors who discuss the theory and application of this:

Here is a great video explaining what are arguments and what is validity

Alex

@acsimon said:
On board with the query for elaboration on the confusion as well as Alex's explanation. I would only add that the validity relation between a set of sentences (i.e., premises) and a sentence (i.e., conclusion) is something that holds as a matter of the structures of those sentences and not their contents.

This is important to keep in mind, not only for the grasp of the concept in question, but also because it might be that there are arguments where the truth of the premises guarantee that of the case conclusion, but it is an invalid argument.

For example:

(1) All Tea contains water.

(2) All gasoline contains oxygen.

Therefore,

(3) All gasoline contains at least one of the same element as is contained in water.

Here, since water is H2O (actually, this is a matter of some controversy in Phil science) the truth of the premises guarentees the truth of the conclusion--true physical identities being neccessarily true. Still, the argument is clearly invalid from the point of view of formal logic since you can substitute in other sentences with exactly the same structures and generate an argument where the premises hold but the conclusion does not. What this makes clear is that the structure of the relevant sentences is what matters for the definition of validity, not their specific contents. This is why general truth preserving (valid) rules of inference can be defined at all (for ppl to memorize for the LSAT, in this case)--A.c.S

Well put!