Does an informal logical fallacy require deception?

Question

Bo Bennett's criteria distinguishing a logical fallacy from a pseudo-logical fallacy has three parts. The third part is:

3. It must be deceptive in that it often fools the average adult.

Douglas Walton, after studying arguments from ignorance, claims that a fallacy in general is a tactic of deception: (page 270-1)

...a fallacy is a sequence of argumentation used in a context of dialogue (of which there may be many types) as a tactic of deception to trick a speech partner in an exchange, or as an underlying systematic, and serious type of error reasoning. Note that a fallacy, according to this conception, is not just any error, weak argument, or violation of a rule of dialogue, but a particularly serious and systematic type of error or sophistical tactic of an identifiable kind, used in argumentation to obstruct a goal of dialogue, or interfere with its realization.

This association of fallacy with deception, rather than rationality, puts it more clearly under ethics than logic.

I am looking for sources, not arguments except as they describe what is in the sources. I want to explore the association of fallacy with deception both for and against. Examples like Bennett and Walton would be on the "for" side.

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Bennett, B. "Pseudo-Logical Fallacies" Logically Fallacious https://www.logicallyfallacious.com/tools/lp/Bo/LogicalFallacies/6/Pseudo-Logical-Fallacies

Walton, D. (2010). Arguments from ignorance. Penn State Press.

Answer 1

Let me make a case for the "against" side.

Comment:

0.1 I won't use the Oxford English dictionary because it's behind a paywall.
0.2 I'll put a bibliography at the bottom of the post.
0.3 I've struggled with the formatting. I apologize if it makes the post difficult to follow.

1. Merriam-Webster's (hereafter "the dictionary") 3rd definition for fallacy is:

An often plausible argument using false or invalid inference

There is no mention of deception (in the 3rd definition).

2. Lews Vaugh, in The Power of Critical Thinking offers another defintion of fallacy without using the word deception:

An argument form that is both common and defective, a recurring mistake in reasoning (p. 561)

3. Both of these are consistent with the definition of a valid argument provided in The Logic Book:

An argument is deductively valid if and only if it is not possible for the premises to be true and the conclusion false. An argument is deductively invalid if and only if it is not deductively valid (p. 11)

(3B) Note: the, The Logic Book does not use the word fallacy, but it does use the phrase "invalid argument" and talks about errors of inference. By the dictionary definition quoted above, that is a fallacy.

(3C) Deception is not mentioned (in this particular definition, or in The Logic Book at all, because the authors seem to believe you can make an invalid inference by mistake).

(3D) Remember that the goal of logic is truth preservation - a valid argument will never start with premises that are all true and lead you to a false conclusion (The Logic Book , p. 1). It can protect you against both subterfuge and mistakes. It's designed for both.

4. In closing:

Bennett says on his website that a fallacy "must be deceptive." In this context 'must' suggest 'necessity'.

To say that deception is necessary for a fallacy implies that it is not possible to have a fallacy without deception. The dictionary and Vaughn offer two definitions of fallacy that are consistent with the formal understanding of validity provided in The Logic Book and depict a scenario where a fallacy can occur without deception and I submit them as a counter-example to the claim that fallacy necessarily requires deception.

Refrences:

Lewis Vaugh,The Power of Critical thinking, 5th ed (New York: Oxford University Press, 2016).

Merrie Bergmann, James Moor, and Jack Nelson, The Logic Book, 3rd ed (New York: The McGraw-Hill, 1998).

Answer 2

jobermark observes in a comment:

But there are clearly times when someone has deluded themselves into accepting a fallacy, in which case there is no deception in the moral sense, only error. It is not immoral to spread your incorrect understanding if you think you are being helpful.

Douglas Walton and Marcin Koszowy consider the argument from authority to be

a dangerous one that can go wrong in some instances and be quite deceptive as a rhetorical tool for strategic maneuvering in argumentation. (page 1 in pdf)

However, this deception could come from two different sources:

Hence there is a normal tendency for the recipient of the argument to be overly intimidated by it, and to presume that it would be inappropriate to raise critical questions about it. So the fallacy in such a case resides in the reaction of the recipient to such an argument, but it may also arise from the way the proponent of the argument puts it forward. (page 5) [my emphasis]

It is possible for the deception to not originate from the way the proponent of the argument puts it forward, but from the recipient's own sense of intimidation preventing the authority from being questioned.

This suggests that jobermark is correct that there is no ethical issue involved with this deception.

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Walton, D., & Koszowy, M. (2014). Two kinds of arguments from authority in the ad verecundiam fallacy. Two Kinds of Arguments from Authority in the Ad Verecundiam Fallacy.