A disagreement can become less useful when a single opinion is treated as a complete description of the person expressing it. Keeping the discussion focused on a particular claim leaves more room for explanation and revision.
Begin by checking what the other person actually means. Summarise their point in terms they recognise and ask whether you have understood it. This step can expose a difference in definitions before it becomes an argument about motives.
Explain your own reasoning with a concrete example and make its limits clear. Avoid adding unrelated complaints to strengthen your case. If the conversation becomes personal, pause and return to the question you were trying to discuss.
Agreement may remain out of reach. You can still identify a shared concern, a fact to check or a practical next step. Respectful disagreement does not require overlooking harmful conduct; it requires being clear about the claim and the behaviour under discussion.