Sophistry
Etymology
From Greek "sophistēs," "expert" or "wise man," from "sophia," "wisdom." The Sophists were paid teachers of rhetoric in classical Athens, and their skill at arguing any side impartially drew the scorn of Plato and Aristotle, who painted them as sellers of trickery. That polemical framing stuck, and the word came to mean plausible reasoning designed to deceive.
noun · /SOF-uh-stree/
Reasoning that is clever and persuasive but deliberately fallacious, meant to win rather than to find the truth.
What it names
The argument built to dazzle — technically slick, rhetorically confident, and quietly rotten at a joint you’re not supposed to inspect.
Example
It was pure sophistry to argue that because the contract didn’t forbid the act, the act was therefore encouraged.
Related idea
Sophistry aims to deceive with bad logic; casuistry applies real principles to specific cases and only becomes an insult when that case-splitting turns into evasion.