Argument from Moral Knowledge

Much natural theology concerning ethics has focused on moral ontology: what grounds the existence of objective moral facts, with theists arguing divine commands or a divine nature provide the best foundation. This argument addresses a related but distinct question: even granting that objective moral facts exist, why should we think our cognitive faculties give us reliable access to them?

This distinction matters because a theory could succeed at grounding moral facts while still leaving open whether creatures like us, shaped by whatever processes produced our cognitive architecture, are positioned to know those facts. The epistemological question has become especially pressing in light of evolutionary accounts of the origin of human moral psychology.

In her influential 2006 paper, Sharon Street posed a dilemma for realist theories of value. Evolutionary pressures shaped human moral judgments because certain evaluative tendencies, such as caring for offspring or punishing free-riders, enhanced reproductive fitness, not because they tracked mind-independent moral truth. If moral realism is true, Street argues, it would be a remarkable coincidence if these fitness-tracking pressures also happened to produce reliably truth-tracking moral beliefs.

Street's dilemma forces realists to either deny any evolutionary influence on moral belief, which is empirically implausible, or accept it and explain why we should still trust our moral faculties, which she argues cannot be done without either abandoning full-blooded realism or embracing an unexplained and troubling coincidence.

David Enoch, a non-theistic robust moral realist, has offered an influential reply. He argues that there may be a third factor explaining the correlation between evolutionarily fitness-enhancing beliefs and true moral beliefs: certain general dispositions, such as valuing cooperation and reciprocity, were both fitness-enhancing and, independently, genuinely good, so the overlap is not a coincidence requiring further explanation.

Critics, including many theists, respond that Enoch's move restates rather than resolves the puzzle: it remains unclear why we should expect this overlap to be substantial across the wide range of human moral judgment, rather than to diverge significantly, unless some further factor (such as a designer aligning survival and truth) is doing explanatory work behind the scenes.

Erik Wielenberg has developed perhaps the most systematic non-theistic response, arguing in 'Robust Ethics' that certain normative and evaluative facts are necessarily true and knowable through direct rational insight, requiring no further explanatory ground, theistic or evolutionary, just as we do not typically demand a further explanation for why basic logical axioms are true and knowable.

Theists such as Mark Linville have pushed back, arguing that treating both the existence and knowability of moral facts as brute is a substantially larger and more ad hoc theoretical cost than positing a rational, good creator who intends and equips creatures to recognize moral truth, since the latter offers a unified, non-coincidental explanation of both facts at once.

The theistic response, developed by philosophers such as Robert Adams and C. Stephen Evans, holds that if a good God created humans with the purpose, or at least the design feature, of being able to recognize and respond to moral truth, then reliable moral cognition becomes exactly what we should expect, independent of any convenient evolutionary overlap between fitness and truth.

This theistic account does not deny that evolutionary processes shaped human cognition; it instead proposes that God may have used or guided such processes toward the further end of producing creatures capable of moral knowledge, providing a teleological explanation that naturalism, on Street's telling, cannot easily supply.

A natural objection to the theistic account is that if God designed humans for reliable moral knowledge, the scale of historical atrocity, self-deception, and persistent moral disagreement seems like poor evidence of successful design. Theists respond by distinguishing the possession of a generally reliable moral faculty from its consistent, undistorted exercise, noting that self-interest, cultural conditioning, and willful suppression of conscience can corrupt moral judgment in practice without indicating that the underlying capacity is unreliable by design.

This distinction parallels standard theistic responses to arguments from the reliability of other faculties, such as reason itself, where fallibility and frequent error in practice are compatible with an underlying capacity that is, in general and in favorable conditions, oriented toward truth.

The debate ultimately turns on how satisfying one finds the various responses to Street's dilemma. Enoch's third-factor and Wielenberg's brute-fact strategies are taken seriously by a significant portion of the philosophical community as adequate, non-theistic ways of preserving moral realism's epistemological credentials, which means the theistic argument functions best as a comparative, not knockdown, case.

What the argument shows at its most careful is that theism offers a distinctively unified and non-coincidental explanation of why creatures shaped by natural processes would also be capable of moral knowledge, a virtue that naturalist realists must work harder, through third-factor or brute-fact moves, to secure for their own positions.