Some people use the word "all" and "some" in their argument sometimes. But not all makes their argument good because they use them wrong.
For example:
All birds fly.
Penguin is one type of bird..
Penguin flies.
This seems valid, but it's not. We all know that penguins don't fly and neither do ostriches which contradics the phrase "all birds fly". So this argument is bad and invalid.
Accorind to Epstein, "All means "Every single one, no exceptions." Sometimes all is meant as "Every single one, and there is at least one." Which reading is best may depend on the argument. And some means "At least one." Sometimes some is as "At least one, but not all." Which reading is best may depend on the argument(Epstein, p.160).
Another example:
Professor Tran requires all his students to use #2 pencil for their exams and students can't take the exam without it.
Becky took Professor Tran's class exam.
Becky used a #2 pencil for the exam.
This argument is valid and good because the word "all" is used properly. We all know that Becky should have not been able to take the exam if she didn't have a #2 pencil to write with on the exam.
I liked how you gave plentiful examples of how to use the word "all." There are no exceptions when using the word all. As you mentions, all means every single thing no exceptions. When explaining all, if one person does not refer to the thing you are trying to explain, then we cannot use the world all. You also gave a good example of explaining a invalid argument by trying to use the word all. I think most people get confused because sometimes one thing can seem like another but its not. All in all, you gave two good examples of what a good argument is and what a bad argument is even when it seems valid.
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