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The Anonymous Fallacy

Introduction

The purpose of this essay is to argue that the claim, "I will not accept your argument because you do not use your real name," is an informal fallacy - an improper way of reasoning.

Professional logicians recognize two necessary and jointly sufficient conditions for a sound argument; (1) The argument is valid, and (2) the premises are true. Thus, there are two and only two ways to refute an argument; (1) demonstrate that the argument is invalid, or (2) demonstrate that at least one of the premises is false. This can be verified by looking in any introductory logic book.

Validity

Arguments are valid or invalid in virtue of their form. The study of logic is the study of the forms that arguments may take and the ways of determining which forms are those of valid arguments and which forms are those of invalid arguments. The paradigm example of a valid argument is called modus ponens; it has the following form:

1a) If P then Q
1b) P
1c) Therefore, Q

In this case, the letters stand for sentences. For example, let P = "Henry is an elephant," and let Q = "Henry is a mammal." We get:

2a) If Henry is an elephant, then Henry is a mammal.
2b) Henry is an elephant.
2c) Therefore, Henry is a mammal.

It is the defining characteristic of a valid argument that, if the premises are true, then the conclusion must be true. A valid argument may still have false premises, but if the premises are true then for the conclusion to be false would be a contradiction. Let us change Q to mean "Henry is a reptile." We get:

3a) If Henry is an elephant, then Henry is a reptile.
3b) Henry is an elephant.
3c) Therefore, Henry is a reptile.

In this example, 3a is false. Yet, it is still the case that IF 3a were true THEN 3c would also have to be true. It would be a logical contradiction to state that, "If Henry is an elephant, then Henry is a reptile; Henry is an elephant; and Henry is not a reptile." Thus, this argument is still valid. In much popular lay-discussion it is common for people to use "validity" as synonymous with "soundness" as meaning, "a good argument whereby the conclusion is proved true." But this is not the logicians' technical definition of the terms.

Arguments are proved invalid by means of a counter-example. The qualities of a valid counter example are; (1) the argument has the same form as the argument one is raising objections against; (2) in the counter-example it is the case that even if all of the premises were true, the conclusion could still be false. From these it is inferred that in the original argument, even if all of the premises are true it is possible for the conclusion to be false; that is, truth of the premises in original argument does not prove the truth of the conclusion in that argument. In other words, believing all of the premises to be true and the conclusion to be false does not generate a logical contradiction.

Since counter examples focus entirely on the form of the argument, rather than the content of the premises, the identity of the person making the original argument is of no relevance.

Truth

Propositions are true or false; and their truth or falsity are determined by their content. One thing it is important to stress is that only propositions - statements - are capable of being true or false. Thus, Tarsky's definition of truth, illustrated by the statement "'Snow is white' is true if and only if snow is white," is not as trivial as it may seem at first glance. "Snow is white" (contained within quotes in the original illustration) refers to a proposition - the sentence "Snow is white." The phrase "snow is white" which is outside the quotes in the original illustration refers to the actual wet, white, cold stuff that falls from the sky in winter. The sentence "snow is white" is true if and only if the wet, white, cold stuff that falls from the sky in winter is actually white.

The Anonymous Fallacy would have us add to Tarsky's definition of truth a condition that the identity of the person who wrote or spoke the statement is known. Thus, "Snow is white" is true if and only if (1) snow is white, and (2) the identity of the person making the claim "snow is white" is known. Yet, clearly, this is not the case. Take, for example, the proposition, "I use the anonymous name Phil in this article." Here, the reader does not know my identity. And, yet, the proposition is clearly true. Or take, for example, the proposition, "There is a hundred dollars buried at the base of the tree at the end of Pine Street," written on a piece of paper flying through the wind. You find this paper; it does not follow from the fact that the paper is unsigned that the proposition is false. Neither does determining whether the proposition is true or false depend on identifying the author - it can be verified by going to the tree at the end of Pine Street and seeing if there is any money buried there.

There are cases in which the anonymity of an author does provide good reason to question the truth of a premises. These are cases where the argument contains a self-referring premise that can not be verified without knowing the identity of the claimant. It is still the case that the truth of the premise does not depend on our knowing the identity of the author, only verifying its truth or falsity depends on that information. For example, if I were to say, "I saw Jim commit the murders," it would be reasonable to hold my anonymity against me. Others could not disprove my statement unless they knew who I was (so they can start rounding up witnesses to the fact I was nowhere near the location when the murders took place). The proposition, "I sometimes use the anonymous name Phil in my posts" is not that kind of proposition. One can round up witnesses for and against this claim without knowing who I really am.

Conclusion

As another example to illustrate my point, I offer this essay. I have attempted to show that the claim, "I will not accept your argument because you do not use your real name," is an informal fallacy. Whether or not I have succeeded is independent of anybody knowing who I really am.

Last modified: 23 Jan 1998
Author: Phil
Comments: galactus@stack.nl
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