---
title: "Naturalistic Fallacy: Moore's Ethics Explained"
description: "The naturalistic fallacy asserts that \"good\" cannot be defined by natural properties like pleasure, making it crucial for ethics in UPSC exams."
url: "https://modeldiplomat.com/learn/glossary/naturalistic-fallacy"
---

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Model Diplomat Research Team · Last reviewed June 22, 2026

TL;DR

- The naturalistic fallacy is the alleged error of defining the moral property "good" in terms of natural or non-moral properties such as pleasure, desirability, or evolutionary fitness.
- How does the naturalistic fallacy differ from the is–ought problem?
- What is the open-question argument and how does it work?
- Is the naturalistic fallacy actually a fallacy?
- Why does the naturalistic fallacy appear in civil-services ethics syllabi?

[Civil Service & Diplomatic Exams](https://modeldiplomat.com/learn/civil-services/glossary)Updated June 22, 2026

The naturalistic fallacy is the alleged error of defining the moral property "good" in terms of natural or non-moral properties such as pleasure, desirability, or evolutionary fitness.

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Example

In his 1903 Principia Ethica, Cambridge philosopher G.E. Moore accused hedonists of committing the naturalistic fallacy by defining "good" as identical to "pleasant," using the open-question argument to expose the error.

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