Critical Reasoning

Received a PM asking me to respond. I think the confusion might be in what this student said a ways back (upthread):

You said when argument saying SOME then it can't be taken as a general inference.. then why we shud bother that whether SOME people THINK OR HOLD the claim , after all they are SOME PEOPLE (as u emphasized)

I think the student might be misinterpreting / misunderstanding something here.

If I say that SOME people like chocolate ice cream, then it is true that SOME people like chocolate ice cream, but it is not necessarily true that MANY or ALL people like chocolate ice cream. As testluv said, you can't infer UP his chain (that is, you can't infer that if something is true for some people or some of the time, then it is true for all people or all of the time).

But you can infer DOWN the chain. If something is true for some people, then it is true for some people, and it is also true for at least one person. If something is true for many people, then it is also true for some people, and it is also true for one person.


Similarly, testluv said that IF choice E had said "SOME environmentalists hold..." That's okay because the argument does establish that MANY environmentalists hold that to be true. If MANY hold it to be true, then SOME do hold it to be true, and AT LEAST ONE holds it to be true. But choice E wouldn't be okay if it said "ALL environmentalists hold..." because we can't infer that "many" means "all."