Logic

What flaws should one be wary of in an argument? Please explain in layman terms (I have not studied philosophy). Thanks.

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In this context, an argument is a set of claims -- the premises -- presented as a reason to accept another claim -- the conclusion. If you are checking for flaws, it is useful to distinguish two fundamentally different ways an argument can go wrong. The first is that one or more or the premises is false or at least unwarranted. The second is that even if all the premises were true, they wouldn't provide a good reason to believe the conclusion. The argument 'Some philosophers are horses therefore some horses are philosophers' suffers from the first flaw (false premise); the argument 'Some people are not philosophers therefore some philosophers are not people' suffers from the second flaw (premise does not provide a good reason for conclusion).

When you are checking an argument, consider both types of flaw. Are the premises true? Do they provide good reason for the conclusion? In tackling the second question, it is often a good idea to ask yourself whether, if the premises were all true, conclusion would absolutely have to be true as well; and whether if the premises were all true they would make the conclusion more likely to be true. If the argument does not pass either of these tests, it suffers from the second kind of flaw: the premises do not provide a good reason for the conclusion.

One final point in this very incomplete answer to your big question. Remember than an argument may be flawed even if its conclusion happens to be true. For an argument with a true conclusion may have false premises (first flaw); and it may have premises which, even if they are true, provide no reason to believe that the conclusion is true (second flaw).

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