To evaluate the effectiveness of an argument the reader needs to assess whether the authors readons and evidence are

To evaluate the effectiveness of an argument the reader needs to check if the read and evidences of the author are true and if the logic used in the argument is valid.

Explanation:

The effectiveness of an argument will depend first in the premises, if they are true or false, in this stage you should check sources, facts and evidences to see how reliable is it. The second stage is to check the logic applied, many arguments had false reasoning, which make then invalid or what it is called logic fallacies. If an argument is valid but the premises are not true it won't be an effective argument, is the premises are true but the logic applied is not correct it won't be an effective argument too.