Moral realism vs anti-realism: are there objective moral facts?

The moral progress argument: we think slavery was wrong, full stop — not just wrong-relative-to-our-values. If moral anti-realism is true, 18th-century slave owners weren't making an error about facts; they were just expressing different attitudes. But this seems clearly wrong. Our condemnation of slavery isn't merely a report of our own feelings; it's a judgment that the slaveholders were mistaken about something objective.

The strongest argument for moral realism is the argument from companions in guilt. If moral anti-realism is true, mathematical and logical truths are also in trouble — both involve non-empirical claims that aren't reducible to natural facts. Most anti-realists don't want to be anti-realists about mathematics. But whatever move they use to preserve mathematical objectivity seems available to the moral realist as well.

The anti-realist's best move — explaining moral progress in terms of improved reasoning and expanded empathy — actually concedes the key point. 'Better reasoning' presupposes standards of reasoning that aren't themselves just expressions of attitude. 'Taking into account all interests equally' presupposes a norm of impartiality that isn't culturally relative. The anti-realist keeps smuggling in objective normative standards through the back door.

The companions-in-guilt move works here too against Street. Mathematical cognition evolved for fitness (numerical reasoning has obvious survival value), yet we don't think this debunks mathematical truth. If cognitive evolution doesn't undermine mathematics, it's unclear why it debunks morality specifically. Street needs an additional argument for why moral cognition is different from mathematical cognition in the relevant way.

Standards of reasoning aren't mysterious: they're constitutive of what reasoning means. Consistency, non-contradiction, evidence-responsiveness are norms internal to the practice of reasoning, not external facts we're tracking. Moral realism requires something stronger: that there are facts about which outcomes matter that are prior to and independent of any reasoning practice. This is what hasn't been established. We can have robust, revisable, improving morality without Platonic moral facts.

Sharon Street's evolutionary debunking argument: natural selection shaped our evaluative attitudes for fitness, not moral truth. If moral facts exist mind-independently, our evaluative faculties have no mechanism for tracking them — the correlation between our moral intuitions and moral facts would be a massive coincidence. The simpler explanation is that moral claims express attitudes and social norms that served evolutionary purposes.

The companions-in-guilt defence fails on disanalogy. Mathematical claims describe structural relationships that are true in all possible worlds given definitions. Moral claims purport to be about a specific kind of non-natural property that certain actions possess. The epistemological access problem is sharper for the latter: how exactly are we detecting 'wrongness' as a property? No plausible mechanism has been offered that isn't just 'intuition,' which is exactly what the debunking argument targets.

The moral progress argument can be explained without realism. We're not saying slaveholders were wrong about a mind-independent fact — we're saying their attitudes failed to take into account the interests of enslaved people, which they systematically discounted due to motivated reasoning and ideology. 'Moral progress' is the expansion of the circle of who counts as a moral patient, driven by better reasoning and more accurate empirical beliefs about those people's capacities. No non-natural facts required.