Final answer:
An opinion must be arguable, based on reasoning rather than bias or emotion, and supported by stronger evidence than a counterclaim to be considered a claim in argumentative writing.
Step-by-step explanation:
To be considered a claim within the context of argumentative writing, an opinion must possess certain characteristics. It must be something that can be argued for or against, indicating it is debatable and therefore forms the basis of an argument. Secondly, it should be based on reasoning, rather than solely on bias or emotion; this evidences a logical foundation for the claim. Lastly, an opinion becomes a claim when it has stronger supporting evidence than a counterclaim, demonstrating its validity through the underpinning facts and inferences.
While it is true that experts' agreement can lend credibility to an opinion, it is not a necessary condition for it to be a claim, as claims can exist in topics where there is no expert consensus. Moreover, the mere fact that an opinion is controversial or 'considered wrong' by some people does not inherently make it a claim; the key is whether it is underpinned by logical, coherent reasoning and evidence.