Naturalistic Fallacy (Encyclopedia of Science and Religion)
The relation between is/ought, fact/value, objectivity/normativity, and science/ethics all touch on the notion of the naturalistic fallacy. In general terms, this notion is an expression of the philosophical argument that one cannot infer from the one to the other; one cannot infer from is to ought, nor can one make an inference from scientific observations to ethical arguments. Any such attempt means committing the naturalistic fallacy. Historically, David Hume (1711776) and G. E. Moore (1873958) were the primary advocates of the invalidity of a moral argument based on such an inference.
In A Treatise of Human Nature (1740) David Hume argued that morals cannot be derived from reason. Rather, feelings should be considered the proper basis of morals. Reason can not account for the passions and affections that arise in questions of morals, but only the questions of objectivity (i.e. truth and falsehood). What is cannot serve as a basis of what ought to be. One cannot derive the moral ought from the objective is.
The term naturalistic fallacy goes back to G. E. Moore, who in Principia Ethica (1903) argued that the notion of the good could not be based by reference to nonmoral entities. The good is a simple, indefinable concept, not composed by other nonmoral parts. This is precisely the problem of the naturalistic fallacy, which points to nature or to some other nonmoral entity and argues that this serves as the basis of moral normativity. Thereby the difference between these parts is ignored, as is the invalidity of inferring from one to the other. By committing the naturalistic fallacy, one would substitute "good" with a nonmoral property.
The ideas of Hume and Moore have had important consequences for the debate on the relation between science and ethics. If Hume and Moore are right, it is not possible to derive normative precepts from scientific observations. Objective findings have no bearing on the question of what one ought to do. The theory of evolution has no implication for ethics. The scientific understanding of human nature is not relevant to the normative understanding of human nature. Is and ought are two separate entities that are to be kept separate if one wants to establish a proper philosophical normative statement.
In a contemporary setting it is debatable whether the inference from is to ought is a fallacy. In various theories of environmental ethics, for example, it is stressed that one cannot isolate ought from is. Holmes Rolston argues that nature holds objective values, and it is necessary for ethical reflection not to ignore this fact. However, the human being's character as a valuer also implies the necessary reflection on these values. In this sense, there is a necessary inference from is to ought. J. Baird Callicott takes a similar stance, even if he does not stress the necessity of the reflective powers of the human being. Morality arises from the membership of human beings in the biotic community. Apart from these theories of environmental ethics, the necessary inference from is to ought is also found in most ethical theories based upon notions of evolution and the relation between the concept of nature and ethics. Therefore, the question of the justifiability of the critique of the naturalistic fallacy stands open.
See also NATURE
Callicott, J. Baird. In Defense of the Land Ethic: Essays in Environmental Philosophy. Albany: State University of New York Press, 1989.
Frankena, William K. "The Naturalistic Fallacy." Mind 48 (1939): 46477.
Hume, David. A Treatise of Human Nature (1740). Oxford: Oxford University Press, 1983.
Moore, G. E. Principia Ethica (1903). Cambridge, UK: Cambridge University Press. 1965.
Rolston, Holmes III. Environmental Ethics: Duties to and Values in the Natural World. Philadelphia: Temple University Press, 1988.
Rolston, Holmes III. Genes, Genesis and God: Values and Their Origins in Natural and Human History. Cambridge, UK: Cambridge University Press, 1999.
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