In an argumentative essay, your job is make the reader agree with your opinion about a controversial topic. You have to (1) state your opinion, (2) give reasons to support your opinion, and (3) argue against the opposite opinion. Overall, you must convince the audience that your side of the argument is correct. To convince the audience, your essay must be balanced—it must include your viewpoint and the opposing viewpoint, or counterargument.
Even though you are agreeing with only one side of an issue, you must think about what the other side would say about your opinion. After you give the counterargument, you must contradict it by showing that it is wrong. If your essay is balanced, a reader is more likely to agree with you.