There’s a word I see far too often in social media exchanges, including from people who otherwise consider themselves thoughtful, educated, and compassionate: “retard.” Let me explain why I find its use so objectionable. When you use “retard” to describe someone you consider foolish, ignorant, or intellectually deficient, you’re drawing on a long history of using intellectual disability as a measure of human worth. The term once had a place in clinical terminology. That history doesn’t make its use as an insult acceptable. In fact, it helps explain why the insult is so damaging. Consider what you’re actually communicating. You’re treating intellectual disability as something shameful, something contemptible, something that makes a person worthy of ridicule. And the people who bear the consequences aren’t necessarily the individuals you’re arguing with. They’re people with intellectual disabilities, their families, and others who have spent decades challenging the stigma attached to those conditions. You can dismantle a bad argument. You can expose dishonesty, ignorance, hypocrisy, or breathtaking stupidity. You can even do it with humor and considerable sharpness. None of that requires borrowing a disability to insult someone. I have no objection to vigorous disagreement. I welcome challenges to my reasoning, evidence, and conclusions. I’ve been wrong before, and I expect I’ll be wrong again. But there’s a difference between intellectual combat and casual cruelty. My rules for engagement with this account are simple: Use the word “retard” as an insult, and you will be muted. Use it again, and you’ll be blocked. Disagree with me all you like. Challenge my evidence. Question my conclusions. Just don’t expect me to accommodate language that demeans people who have nothing to do with our disagreement.