Which one of the following statements most accurately characterizes a difference between the two passages?

christophergogo on May 21, 2020

Around the 30 minute mark, the instructor says that the second argument/example is invalid because it has false premises. I think he meant to say that the argument is unsound, as that argument actually is valid. After all, you can have a valid argument with false premises. For instance, I could construct an argument like:

1. If the animal has four legs, then it is a dog.
2. The animal has four legs.
3. Therefore, it is a dog.

P1 is obviously false, but this is just modus ponens, so it has to be valid. The problem is that it's unsound, not that it's invalid.

Similarly, while P1 is false in the second argument/example in the video, the form is valid. So, the argument is unsound, not invalid.

I think if he did misspeak, then that would explain some of the confusion I'm seeing in these comments. Some are wondering why the truth value of the premises has any relevance to the validity of the argument, and I think they're quite right to point this out. But I may be missing something myself, in which case I would really appreciate an explanation that addresses this. Thanks! :)