From T. Edward Damer’s, Attacking Faulty Reasoning:
An opinion is an unsupported claim; an argument is a supported claim.
The expression of personal opinion is one of the most commom forms of verbal exchange, and since reasons for our opinions are often not requested, we are unaccustomed to defending them and even lulled into thinking that reasons are not required. “Everyone is entitled to his or her own opinion,” it is often said. This is true, but the question here is not whether one has the right to express an opinion; it is a question of which opinions deserve our acceptance. If an opinion is not accompanied by reasons to support it, it is not possible to determine whether it merits our acceptance.
…Since some of our opinions also conflict with the opinions of others, we know that some of us are now holding false opinions; for if there are two opposing or different opinions about some matter, at least one of them is false. But which is it? That question can be answered only by evaluating the quality of the argument presented on behalf of each view.