Naturalistic fallacy — A term coined by G. E. Moore in Principia Ethica (1903) for the error of identifying the good with some natural property, such as pleasure, or with a metaphysical one. For Moore, “good” names a simple, indefinable property that cannot be reduced to any other. His main instrument is the open question argument: for any proposed definition, for example “good is what produces the most pleasure,” it remains a meaningful question to ask “but is that good?”, which would show that the expressions are not synonymous. Moore aimed the criticism at authors such as Herbert Spencer and, in part, at John Stuart Mill, whose utilitarianism would try to define the good by pleasure or desire. The naturalistic fallacy should not be confused with the “is-ought problem” associated with David Hume, who in the Treatise of Human Nature (III.1.1) observes that authors move from propositions with “is” to propositions with “ought” without justifying the transition. The two themes are related but distinct: Hume’s concerns logical inference, Moore’s concerns definition. Frankena (1939) objected that the name is inappropriate, since the error is not strictly a logical fallacy. In everyday usage, “naturalistic fallacy” also designates the appeal to nature, that is, the inference that something is good because it is natural, or that something ought to be because it is; this use differs from Moore’s. See also the notion of fallacy.
See also: G. E. Moore, Hume, Ethics, The Good.
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