Existential Fallacy
Frank Scalambrino
[W]hen I think a thing, through whichever and however many predicates I like (even in its thoroughgoing determination), not the least bit gets added to the thing when I posit in addition that this thing is.
Immanuel Kant, Critique of Pure Reason
The existential fallacy occurs when we erroneously suppose some class or group has members. In other words, statements may be true about classes or groups even if no members of the class or group exist. Consider the class of things that are unicorns; we can say that it’s true that unicorns have one horn, but we need not (and should not) think that individual unicorns (members of the class of unicorns) exist.
In terms of syllogistic argumentation, this is a formal fallacy in that it results when the premises are universal in quantification and the conclusion is particular. That is to say, the premises of an argument may be stated in terms of “All” and “None,” and the premises may be true; however, the truth of the premises does not necessitate the truth in regard to “Some” of the contents of the premises since the contents may not exist. For example, the claim “All humans are mortal” is true; therefore, it logically follows that “Some humans are mortal.” However, notice that although it is true to claim, “All unicorns are one-horned creatures,” it would be false to say,
“Some unicorns are one-horned creatures,” insofar as “Some” is understood to mean “there are some” unicorns in existence which are one-horned creatures.
Put differently, some universal properties may be true without being instantiated, that is, without existing. For example, it may be true that “All violators will be prosecuted” even if there are no violators. It may be true that “No quitters will win” even if there are no quitters. When we suppose some members of a class or group exist, we might be guilty of erroneously importing existence.
Put more concisely, universal claims do not have valid “existential import.” Hence, when the truth-value of a claim depends on the existence of members of the class or group under consideration, the question of valid existential import is involved. In this way, the following is not illogical: “All Kings of France must reside in France. Therefore, the King of France lives in France.” However, because the conclusion requires that the “King of France” exists, the argument commits the “existential fallacy.”In the history of logic, the existential fallacy may be traced to dictum de omni, which refers to the principle in Aristotelian logic that whatever is said universally of a subject is said of everything that is contained under such a subject. Yet, in light of this principle, existence claims may become ambiguous. Therefore, following logician George Boole, “first-order predicate calculus” avoids possible ambiguity by making existential import explicit. In this way, universally quantified statements are treated as if they are conditional. That is to say, “All Ps are Qs” is translated into: “For any/every x, if x is a P, then x is a Q.” By replacing the “All” or “None” with “For every,” first-order predicate calculus removes the ambiguity.
Controversy regarding the relation between the logic of claims and existence may be found throughout the history of philosophy. One of the more famous examples is associated with the above Kant quotation, namely, that “existence is not a predicate.” In his section of the Critique of Pure Reason titled, “Of the Impossibility of an Ontological Proof of the Existence of God,” Kant (1996) claimed existence is not a property to be predicated regarding an object (A600/B628). The basic idea is that we cannot ensure “existence” by means of the use of language alone. In other words, the truths of semantic logic do not necessitate the existence of the entities to which the truths refer. This is the case insofar as by “semantic logic” we mean the logic of the meaning of language.
Though not itself a proof against the existence of God, Kant pointed out that the “ontological” strategy (associated with Anselm and Descartes) to argue for the existence of God takes the meaning of terms such as “perfection” and “greatness” to derive a term as a maximum. Yet, though the meaning of the term “perfect” maximally entails not lacking in any way, it does not follow that that to which the maximal term refers must “exist.”In order to avoid this fallacy, one should look for empirical verification of the existence of whatever entity may be in question. Of course, there are cases in which empirical verification may be more or less simple. To verify that your motor vehicle has not been stolen, you may go look. Notice, when you look, you have a clear and distinct concept regulating your investigation. In other words, there are a number of ideas regulating where you look and for what you are looking. In this way, the question of what counts as evidence is, to some extent, tied to our understanding of that for which we are seeking evidence. Thus, in less simple cases when we seek empirical verification of some entity’s existence, we should ensure that we properly understand the concept employed in the verification process.
Reference
Kant, Immanuel. 1996. Critique of Pure Reason, translated by Werner S. Pluhar. Indianapolis, IN: Hackett Publishing.