Good and Bad Reasoning (Sound and Unsound Reasoning)

In evaluating an argument, the first step is to identify the conclusion and the premises of the argument. Consider this argument about capital punishment:
Two premises:
            1.) It is always wrong to kill a human being.
            2.) Capital punishment is the killing (taking the life) of a human being.

        and the conclusion

 3.) Therefore, capital punishment is wrong.

The first premise (It is always wrong to kill a human being) is questionable. Most of us do not believe is it always wrong to kill a human being: some wars, like World War II, are justified. Thus, we should not accept the conclusion of this argument unless different and better reasons can be given to support it. The conclusion may be true but it is not demonstrated to be true based upon these premises (at least one of which is false). In summary, the first condition of deveoping or evaluating a good argument requires that we use the best information that we have or can get (background information and beliefs) to decide if we should accept or reject the premises of the proposed argument.

Valid reasoning: the logical relationship between the premises and the conclusion of an argument?
The second criterion of good reasoning or sound reasoning requires that an argument be valid. Validity is concerned with the connection between the premises and the conclusion of an argument. An “argument is valid” means that if we were justified in believing the premises, then we are also justified in believing the conclusion. A valid argument does not tell us that the premises are believable.  We can have a valid argument with false premises and a false conclusion. For example,

    1.      All Murray State graduates are good-looking.
    2.      All good-looking persons are highly intelligent.
    3.      All Murray State graduates are highly intelligent.

    The argument is valid because if “all Murray State graduates were good-looking” and if “all good-looking persons were highly intelligent”, then the claim that “all Murray State graduates are highly intelligent” would also be true. In fact it would be impossible for the conclusion to be false (Your would contradict yourself if your said all Murray State graduates were good-looking” and  “all good-looking persons were highly intelligent” but it is not the case that All Murray State graduates are highly intelligent. The argument is valid even though both the premises and the conclusion are false.  All arguments with the same logical form as the argument above (AAA-1) are valid because if we were justified in believing that the premises were true of arguments have this logical form, then we would be justified in believing that the conclusion is true.
    I have served on the graduation committee at MSU for over 30 years and lined up MSU graduates on graduation day. I can tell you that most MSU graduates are good-looking students. But in my 30 years I have seen at least some less than good-looking graduates. Thus premise 1 is not believable. You can develop an argument to show the premise 2 is unbelievable.