Why is something considered a logical fallacy?

[fakename]

Logic investigates and formalizes noetic acts (acts of the intellect, especially judgment and inference), not psychological processes (like emotions, feelings, qualia, moods, will power, etc.) in the modern sense of psychology.

I tend to investigate issues historically like Aristotle; so I start with formal logic since began the study. Symbolic logic and predicate calculus came later and are great avenues of inquiry too.

To some extent I think you’re onto something re your analysis of the difference (such as it may be) between material and formal fallacies. I agree that material fallacies could be formally correct, but contain a proposition or propositions held either explicitly or implicitly that are false. Hence the distinction between fallacies in the form of the argument versus the matter of the argument.

It seems to work. Take post hoc, propter hoc. Take an oversimplified case: I clap my hands and it thunders. So I conclude that my clapping caused it to thunder.

All successive events move from cause to effect.
But thunder followed my clapping.
Therefore my clapping stands to thunder as cause to effect.

The problem is the major premise, not the form.

Or consider ad hominem arguments.

No dirty, rotten, low-down, bankety blanks make true assertions.
Joe asserts smoking is bad for your health.
Joe is a dirty, rotten, low-down, bankety blank.
So Joe’s assertion is false.

One could spell that out into a series of correct syllogisms, but the major is false.

It seems in the case of material fallacies many can be grouped together and named perhaps all containing the same false premise. Some however are just diversionary: straw man, irrelevant conclusion. Others are circular (begging the question) or verbal sleight of hand (many questions, false dilemma). Still if one rooted around enough they could probably find an implicitly held false premise at the bottom of many of them. Either way the fallacy would not be in the form, but in the matter of the argument.

To put it together:

I actually heard a legal expert say the following on a talk show. “All men who murder their wives have had affairs and we know Scott Peterson had an affair, so it’s pretty easy to figure out who’s guilty here.”

Put in logical form the syllogism (committing the fallacy of an undistributed middle) goes:
All men who murder their wives have had affairs.
Scott Peterson had an affair.
So Scott Peterson is guilty of murdering his wife.

It fits perfectly with the following:
All cows are animals.
Lassie is an animal.
So Lassie is a cow.

BUT the argument could also be attacked materially. How well-conducted were the studies that yielded the major premise? Has it really been established that Peterson had an affair?

Although it seems perfectly likely that the material fallacies are all distinct from the formal ones, I wonder about this example: a bad man only says false things, this guy is bad, so he only says false things. In this syllogism we could say that materially, badness has no connection with falsity. So for instance the class of bad things is not subsumed into the class of false things such that if you see a bad thing that guarantees it is also wrong. So if that , it must be true that a bad thing is not necessarily right or wrong or that it is sometimes associated with it. In both cases the syllogism would be amended either as (1) No bad thing is either right or wrong, this guy is bad, therefore no syllogism is possible for formal reasons or (2) Sometimes a bad thing is wrong, this guy is bad, and therefore again there is no syllogism possible in this case because of wrong form. Indeed even if we conceded that there was a necessary connection between the falsity of a statement and a bad thing (in the case that no bad thing is ever wrong), we could still conclude that knowing both this and that a bad man says only false things, would prove that there is a formal contradiction and that even then a syllogism could not be formed.

Perhaps, it is true that formal fallacies are consistent with material errors but that doesn’t make one type of fallacy the other type? This is true because there are other criticisms of my fallacious syllogism which are other than formal. Yet again, it seems that every criticism can be reduced to a formal one in that every criticism can be couched in the terms (as in the Peterson example) only some men who have affairs kill their wives, or No Peterson had an affair, etc. Then again, even if we change the premises even formally we could say that some changes still yield correct syllogisms: No men who have affairs kill their wives, Peterson had an affair, so Peterson did not murder his wife. But again, someone who resorted to a material criticism would have to say either that “All men who have affairs kill” or “No men…” or “there is no connection between the two terms”. Once more I ask, are material fallacies all that different from formal ones?

 

[Fr_of_Jazz]

Although it seems perfectly likely that the material fallacies are all distinct from the formal ones, I wonder about this example: a bad man only says false things, this guy is bad, so he only says false things. In this syllogism we could say that materially, badness has no connection with falsity. So for instance the class of bad things is not subsumed into the class of false things such that if you see a bad thing that guarantees it is also wrong. So if that , it must be true that a bad thing is not necessarily right or wrong or that it is sometimes associated with it. In both cases the syllogism would be amended either as (1) No bad thing is either right or wrong, this guy is bad, therefore no syllogism is possible for formal reasons or (2) Sometimes a bad thing is wrong, this guy is bad, and therefore again there is no syllogism possible in this case because of wrong form. Indeed even if we conceded that there was a necessary connection between the falsity of a statement and a bad thing (in the case that no bad thing is ever wrong), we could still conclude that knowing both this and that a bad man says only false things, would prove that there is a formal contradiction and that even then a syllogism could not be formed.

You answered your own question . . . correctly. The syllogism was formally valid, but, as you said, you challenged it materially. Once the major is emended (to a particular affirmative) no conclusion can be drawn from it formally–two particular premises yield no conclusion.

Perhaps, it is true that formal fallacies are consistent with material errors but that doesn’t make one type of fallacy the other type? This is true because there are other criticisms of my fallacious syllogism which are other than formal. Yet again, it seems that every criticism can be reduced to a formal one in that every criticism can be couched in the terms (as in the Peterson example) only some men who have affairs kill their wives, or No Peterson had an affair, etc. Then again, even if we change the premises even formally we could say that some changes still yield correct syllogisms: No men who have affairs kill their wives, Peterson had an affair, so Peterson did not murder his wife. But again, someone who resorted to a material criticism would have to say either that “All men who have affairs kill” or “No men…” or “there is no connection between the two terms”. Once more I ask, are material fallacies all that different from formal ones?

Wait, did you mean to say “Perhaps, it is true that formal fallacies are consistent with material errors but that doesn’t make one type of fallacy the other type?”? It wouldn’t in that case be a question, but a correct statement.

Or did you mean to say “Perhaps, it is true that formal fallacies are consistent with material errors but doesn’t that make one type of fallacy the other type?”? In this case, no, by definition.

As I said: It seems in the case of material fallacies many can be grouped together and named perhaps all containing the same false premise. Some however are just diversionary: straw man, irrelevant conclusion. Others are circular (begging the question) or verbal sleight of hand (many questions, false dilemma). Still if one rooted around enough they could probably find an implicitly held false premise at the bottom of many of them. Either way the fallacy would not be in the form, but in the matter of the argument.

In any event, it is true that logic deals with propositions as does reasoning in general, but the process of squaring a proposition with reality (before use in a syllogism), as far as logic is concerned, is a material process, not formal. The process is beyond mere formal considerations.