Naturalistic Fallacy

Appeal to Nature. One aspect of the Naturalistic Fallacy is the (false) idea that whatever is natural cannot be wrong. Hence, if we can find an example of a certain behavior "in nature," then that behavior should be acceptable for human beings.

Deriving 'ought' from 'is'. Another aspect of the Naturalistic Fallacy is a move from a "fact," i.e. a declarative or descriptive utterance, to an imperative or prescriptive utterance. The conclusion may be about moral duties or about ideal states of affairs; but the unstated (and false) premiss is that we must always accept things as they are. In some cases, this may very difficult to distinguish from the fallacy of Appeal to Tradition.

However, once we have acquired the habit of refraining from moral judgments outside the human realm, the Naturalistic Fallacy then tries to convince us that we ought to condone, within the context of human affairs, whatever can be described as "natural."  "Nature" may mean, of course, other species, but it may also include humans in a more "natural" state (i.e. non-civilized human societies.) The claim that something is "natural" may even just be an appeal to human nature, civilized or not. For example, in The African Queen Humphrey Bogart tries to justify his drinking of rum by saying, "Have a heart, miss. It's in me nature." (To which Katherine Hepburn replies, "Nature, Mr. Ornat, is what we were put into this world to rise above!")

David Hume is the philosopher most associated with the principle that one cannot validly derive an "ought" statement from an "is" statement, although G. E. Moore made good use of this principle in his Principia Ethica. The principle is sound, of course. From the claim that a ring is made of gold it does not directly follow that the ring is valuable. We must also know that gold is valuable.

On the other hand, "ought" arguments do often turn on a consideration of facts. Whether we should spend more on education may depend on specific facts about student performance. Whether we should spend more on the military depends on specific facts about the current state of the military and upon specific facts about threats to this country. Hence, one way to reason badly is to propose an argument in which the relevant facts are omitted or misrepresented. An argument that appeals to well-established facts is much more likely to be good reasoning than one that does not.

Moreover, the distinction between facts and values is not always clear cut. If I say "This steel beam is strong," I probably mean that it is strong enough to serve some purpose, such as supporting a bridge. I am, in short, judging its value to someone concerned with building a good bridge. The concept of "strength" seems objective enough, but it is actually quite value-laden. Good reasoning recognizes this subtle interplay between fact and value.

The Naturalistic Fallacy mimics good reasoning by claiming to be "factually based," i.e. by appealing to well-established facts, but it is doing so in a context in which a choice of ideals is  actually the issue. It does not so much recognize the interplay between fact and value as try to reduce questions of value to questions of fact.