Ethical naturalism holds that moral properties are natural properties that can, in principle, be investigated through reason and empirical evidence. Ethical non-naturalism holds that moral properties are real but irreducible to natural or scientific properties.
Both positions are usually forms of moral realism and cognitivism: moral statements express beliefs, can be true or false, and may describe objective moral facts. Their disagreement concerns the nature of those facts.
| Issue | Naturalism | Non-naturalism |
|---|---|---|
| Moral properties | Identical with or reducible to natural properties, such as well-being or the satisfaction of preferences | Distinct, irreducible, non-natural properties, such as goodness or rightness |
| Moral knowledge | Acquired through observation, experience, and rational investigation of natural facts | Often acquired through rational reflection or moral intuition |
| Example | “Good” might mean “maximizes human flourishing” | Goodness cannot be completely defined using natural terms |
| Main strength | Connects ethics to observable features of human life | Preserves the distinctive, normative force of moral judgments |
| Main challenge | Must explain why identifying natural facts does not illegitimately produce moral conclusions | Must explain how humans detect non-natural properties and why such properties exist |
For example, a naturalist might claim that “generosity is good” is true because generosity promotes human flourishing. A non-naturalist may agree that generosity is good but deny that goodness simply means promoting flourishing.
G. E. Moore defended non-naturalism through the open-question argument. If “good” meant “produces pleasure,” it would be meaningless to ask, “Producing pleasure is natural, but is it good?” Because this remains an intelligible, open question, Moore argued that goodness cannot be defined as a natural property.
A common misconception is that non-naturalism means moral facts are supernatural or religious. Non-natural properties are instead understood as unique, irreducible normative properties.
In an IB Philosophy response, define both positions, identify their shared cognitivist basis, and compare how they explain moral properties and knowledge. To evaluate them, apply Moore’s open-question argument and assess whether naturalism commits the naturalistic fallacy or whether non-naturalism creates an epistemological problem.
