Running the Euthyphro Test

The Euthyphro test takes any claim of the form "X is wrong because an authority forbids X" and asks which way the because runs.

Take "insider trading is wrong because the regulator forbids it." Ask the test's one question: would a rule change make the trading right? If yes, wrongness hangs on the rule alone — the arbitrariness horn, and the claim's defender must accept that a different rule flips the verdict. If no — the trading would stay wrong regardless — then a standard beyond the rule is doing the work: harm to other investors, broken fairness. Name that standard, restate the argument on it, and the authority drops out as the source of the wrongness, keeping only the job of enforcing it. The test runs the same on regulators, employers, majorities, and divine commands: an authority either marks wrongness or makes it, and each answer carries the price its horn names.