Why is something considered a logical fallacy?

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As someone who reads about logic and such, it occurred to me that no book has ever defined what a fallacy was or described what makes any arbitrary thing fallacious.

This is especially jarring if one considers the argument from authority fallacy.

Obviously, something is not rendered true just because someone else says it is.

Yet, this statement itself is controversial for we believe in an infallible authority then anything it says is by definition true.

So what makes a thing essentially a fallacy?
 
A fallacy occurs when the conclusion does not follow from the premises. Note that a non-fallacious argument can yield a false conclusion if the premise is false. Note also that a fallacious argument can still yield a true conclusion (whether or not the premise is true).

Here are some examples:

A non-fallacious argument with true premises and conclusion:

Socrates was a man (besides Jesus).
All men (besides Jesus) are mortal.
Therefore, Socrates was mortal.

A fallacious argument with true premises and conclusion:

Socrates was a man (besides Jesus).
All men (besides Jesus) are mortal.
Therefore, the Earth is round.

A fallacious argument with false premise and true conclusion:

The Catholic Church is the Whore of Babylon.
Therefore, the Earth is round.

A non-fallacious argument with false premise and true conclusion:

The Catholic Church teaches error.
Therefore, the Catholic Church exists.

A non-fallacious argument with false premise and conclusion:

Socrates was immortal.
Therefore, Socrates was not mortal.

A fallacious argument with false premise and conclusion:

Socrates was immortal.
Therefore, the Earth is flat.

A fallacious argument with true premise and false conclusion:

Socrates was mortal.
Therefore, the Earth is flat.
 
Do you carry your books to school or do you buy your lunch?
 
A fallacy occurs when the conclusion does not follow from the premises. Note that a non-fallacious argument can yield a false conclusion if the premise is false. Note also that a fallacious argument can still yield a true conclusion (whether or not the premise is true).

Here are some examples:

A non-fallacious argument with true premises and conclusion:

Socrates was a man (besides Jesus).
All men (besides Jesus) are mortal.
Therefore, Socrates was mortal.

A fallacious argument with true premises and conclusion:

Socrates was a man (besides Jesus).
All men (besides Jesus) are mortal.
Therefore, the Earth is round.

A fallacious argument with false premise and true conclusion:

The Catholic Church is the Whore of Babylon.
Therefore, the Earth is round.

A non-fallacious argument with false premise and true conclusion:

The Catholic Church teaches error.
Therefore, the Catholic Church exists.

A non-fallacious argument with false premise and conclusion:

Socrates was immortal.
Therefore, Socrates was not mortal.

A fallacious argument with false premise and conclusion:

Socrates was immortal.
Therefore, the Earth is flat.

A fallacious argument with true premise and false conclusion:

Socrates was mortal.
Therefore, the Earth is flat.
In what sense does the conclusion not follow from the premise in these examples? For instance, Socrates being mortal might, in some system of philosophy, imply that the earth is flat. This seems less like a decision for logic and more of a decision for actual philosophy.

Rather, is it that the premises don’t imply the conclusions in the sense that a bad syllogism is wrong for its form and not for its contents? All B is C, Some C is D, so Some B is D?

Do you think that the contents bear some relationship to the form? For instance, the meanings of “Socrates” and “Mortal”, “Earth” and “Flat”, cannot be connected because they imply a badly formed argument; e.g. Socrates is Mortal, No Socrates is Earth, No Mortal is necessarily Flat, So Socrates is not Necessarily Flat and the Earth may be flat or not; for the definitions and consequently the argumentative form, does not allow us to conclude anything about the earth’s flatness? Is this why an argument can be fallacious?
 
In what sense does the conclusion not follow from the premise in these examples? For instance, Socrates being mortal might, in some system of philosophy, imply that the earth is flat. This seems less like a decision for logic and more of a decision for actual philosophy.

Rather, is it that the premises don’t imply the conclusions in the sense that a bad syllogism is wrong for its form and not for its contents? All B is C, Some C is D, so Some B is D?

Do you think that the contents bear some relationship to the form? For instance, the meanings of “Socrates” and “Mortal”, “Earth” and “Flat”, cannot be connected because they imply a badly formed argument; e.g. Socrates is Mortal, No Socrates is Earth, No Mortal is necessarily Flat, So Socrates is not Necessarily Flat and the Earth may be flat or not; for the definitions and consequently the argumentative form, does not allow us to conclude anything about the earth’s flatness? Is this why an argument can be fallacious?
Put it this way: the logical consistency/validity (or inconsistency for that matter) of an argument does not refer to the truth of the premises or the conclusion, but only whether the conclusion follows necessarily (or not) from the premises.

Consider this: All A is B. Can one conclude necessarily “All B is A”? We know that from what we are given in the grammar of the statement that B can be and likely is a broader category than A. So the converse is not necessarily true: it does not follow. From “All cows are animals” we cannot get “All animals are cows.”

Now consider the following simple AAA-1 syllogisms.

All A is B
All C is A
So, all C is B.

All mammals nurse their young.
All cows are mammals.
So, all cows nurse there young.

All mammals are cold-blooded.
All cows are mammals.
So, all cows are cold-blooded.

All the syllogisms are valid, but the last one is false because the major premise false.

On the other hand from the fallacy of an argument we cannot necessarily conclude that the conclusion is false.

A classic example I saw was: what is 16/64? Well, all you have to do is cancel out the 6s and you get 1/4. Well, that gets a yellow flag for an illegal math procedure, but the answer just so happens to be right. Exposing a fallacy, in and of itself, only shows that the given conclusion has not been proven, not that it is false.
 
Put it this way: the logical consistency/validity (or inconsistency for that matter) of an argument does not refer to the truth of the premises or the conclusion, but only whether the conclusion follows necessarily (or not) from the premises.

Consider this: All A is B. Can one conclude necessarily “All B is A”? We know that from what we are given in the grammar of the statement that B can be and likely is a broader category than A. So the converse is not necessarily true: it does not follow. From “All cows are animals” we cannot get “All animals are cows.”

Now consider the following simple AAA-1 syllogisms.

All A is B
All C is A
So, all C is B.

All mammals nurse their young.
All cows are mammals.
So, all cows nurse there young.

All mammals are cold-blooded.
All cows are mammals.
So, all cows are cold-blooded.

All the syllogisms are valid, but the last one is false because the major premise false.

On the other hand from the fallacy of an argument we cannot necessarily conclude that the conclusion is false.

A classic example I saw was: what is 16/64? Well, all you have to do is cancel out the 6s and you get 1/4. Well, that gets a yellow flag for an illegal math procedure, but the answer just so happens to be right. Exposing a fallacy, in and of itself, only shows that the given conclusion has not been proven, not that it is false.
I understood all that, but I just don’t understand how this connects with the material fallacies of logic which all seem, to me, to be criticisms of the content of what is being said.

Again this argument:

God is infallible
Infallible people should be believed
You should believe anything God says (because he said it)

Is also a formally valid argument and some might say a sound argument too. But yet it falls victim to the fallacy of “argument from authority” in that anyone who believes it necessarily believes in the validity of the invalid “argument from authority” style.

Perhaps though, one could square this argument with validity. The argument itself is valid but the conclusion may not be true (and true and false have nothing to do with validity). As such, the possibly false conclusion is cannot be called invalid but it can be untrue as regards a set of other statements known to be true (like the class of statements defining what a material fallacy is).

In the last analysis though, I still don’t know the reason for why material fallacies are still fallacies. If it is the same as why formal fallacies are fallacies then tell me both the fact that they are, and why we should accept such facts in light of their apparent contingency (that an argument from authority is invalid seems like a contingent fact and as such, one requiring evidence). As I said before, the material fallacies seem like criticisms of content and not of form.
 
There are many excellent books on the subject. I would recommend the following:

If you really want to study logic and gain a comprehensive understanding:

A Concise Introduction to Logic by Patrick J. Hurley - the eleventh edition is currently available for purchase, although it is expensive ($142 on Amazon) and expansive (736 pages) - you might peruse a copy at your local library.

I rather doubt this to be the case, as I find it illogical to make a sweeping statement like ‘there are no books on the subject’ on a web forum - which means you could easily google the topic and see how wrong is that statement.

I would recommend the following to ‘dip your toe in the water’

Logic Made Easy: How to Know When Language Deceives You by Deborah Bennett

How We Know What Isn’t So: The Fallibility of Human Reason in Everyday Life by Thomas Gilovich

How to Win Every Argument: The Use and Abuse of Logic by Madsen Pirie

Nonsense: Red Herrings, Straw Men and Sacred Cows: How We Abuse Logic in Our Everyday Language by Robert Gula

Crimes Against Logic: Exposing the Bogus Arguments of Politicians, Priests, Journalists, and Other Serial Offenders by Jamie Whyte
 
There is a difference between validity and truth.
For example a true and valid argument is,
  1. All men are mortal.
  2. Socrates was a man.
  3. Therefore, Socrates was mortal
    Here is an argument that is valid but not true,
  4. All Martians eat snakes.
  5. Bob is a Martian.
  6. Therefore, Bob eats snakes.
    Here is an argument that is true but not valid,
  7. Obama is US president.
  8. North Carolina is part of the United States.
  9. Therefore, the Copernican theory ( that the sun is the center of the solar system) is correct.
    A fallacy deals exclusively with the structure (skeleton) of an argument. Another example of a fallacy( in particular the ad hominum fallacy)
  10. Manson tells lies.
  11. Manson said that 1+1=2.
  12. Therefore, 1+1 does not =2.
    To say that what is a fallacy is a matter of opinion is to say that 1+1=2 is only your opinion. I strongly disagree with that proposition!
 
Here is a little article I wrote for Atheist which I think might be relevant here.

In order to use language/speech correctly you have to adhere to the universal laws of logic unless of course you want to be irrational and sound like a blabbering fool. Take the law of non-contradiction for example. If I make statements like this, – ‘God exists and God does not exists’ – ‘I am a Christian and Not a Christan’ – ‘I can be and not be’, they would all be False Statements! All those statements would be illogical because they would contradict themselves. They wouldn’t make sense so in order to make sense we must adhere to the universal laws of logic. When we adhere to the laws of logic we are rational and when we don’t we are irrational.

If the universal laws of logic exists then absolute truth exists. If absolute truth exists then God exists. The basic reasoning behind this is that you cannot give what you do not have, for example: I do not have a million dollars to give you therefore I cannot give you a million dollars. The universal laws of logic cannot be absolutely true by themselves they require a transcendent absolute truth (God) that can give these laws the essence to be absolutely true.

If God does not exists then the laws of logic are not absolutely true then I have absolutely no reason to obey them therefore I do not have to be rational, nor does anybody else. We know that we ‘ought’ to be rational therefore we appeal to the universal laws of logic proving absolute truth exists therefore proving God exists.

Every-time you think/talk/write you are using Gods absolute universal truths of logic therefore proving Gods existence, even when you are illogical.

Here is a short list of the definitive universal unchanging laws of logic…
gregcaughill.com/philosophy-wiki/learn-logic/34-the-laws-of-logic.html
 
I would also say the laws of logic exist just like mathematics exist. We are simply discovering them. They are hardwired into us as humans beings (mind and spiritual soul). Technically, it’s not even our logic, it’s Gods logic and we are simply borrowing it. 😉
 
How can anything that is not contingent (God) be proved contingently?
 
I would also say the laws of logic exist just like mathematics exist. We are simply discovering them. They are hardwired into us as humans beings (mind and spiritual soul). Technically, it’s not even our logic, it’s Gods logic and we are simply borrowing it. 😉
I meant the laws of logic are hardwired into us so that we are capable of reasoning. Not that mathematics is hardwired in us because mathematics is definitely not it is purely outside of us.

God cannot be proven in the strict empirical sense but through reasoning you can prove/know that God exist. Empiricist deny using reasoning to know the Truth (Which is God) because they believe all Truth is gained through Observation and Experimentation. Which is a lie. Claiming that all Truth is gained through Observation and Experimentation is a philosophical claim therefore refuting their claim that all truth is gained through Science. If all Truth is gained through science then why use philosophy to determine that Truth? 😉

Jesus is God. God is the Truth and all Truth comes from God. Everything in existence is screaming out for creator God by it’s Truth.
 
I understood all that, but I just don’t understand how this connects with the material fallacies of logic which all seem, to me, to be criticisms of the content of what is being said.

Again this argument:

God is infallible
Infallible people should be believed
You should believe anything God says (because he said it)

Is also a formally valid argument and some might say a sound argument too. But yet it falls victim to the fallacy of “argument from authority” in that anyone who believes it necessarily believes in the validity of the invalid “argument from authority” style.
Philosophically, the argument from authority is the weakest argument since assent in philosophy is based on publically available evidence: direct observation/experience, self-evident truths, or reasoned argument from them.

But theology is based on the word of God apprehended and assented to in faith; and so arguments in theology are based on the word of God as the authority. However it is possible to show demonstratively that supposed contradictions in the Faith or to the Faith are not necessary.
Perhaps though, one could square this argument with validity. The argument itself is valid but the conclusion may not be true (and true and false have nothing to do with validity). As such, the possibly false conclusion is cannot be called invalid but it can be untrue as regards a set of other statements known to be true (like the class of statements defining what a material fallacy is).
In the last analysis though, I still don’t know the reason for why material fallacies are still fallacies. If it is the same as why formal fallacies are fallacies then tell me both the fact that they are, and why we should accept such facts in light of their apparent contingency (that an argument from authority is invalid seems like a contingent fact and as such, one requiring evidence). As I said before, the material fallacies seem like criticisms of content and not of form.
Aristotle distinguished formal fallacies, fallacies in language, and material fallacies. Material fallacies are fallacies outside of language in the matter of the argument, i.e., in the reasoning process itself. Examples would be the different permutations of Irrelevant Conclusion, ad hominem arguments, guilt by association, loaded term, etc.

In other words regarding material fallacies, Aristotle would hold you’re not thinking straight if you think that by attacking the person you have refuted their argument.

Some logicians now include a separate category, Inductive Fallacies, like False Generalization, False Cause, Common Cause, Confounding Variables, etc.

Is the definition of Material Fallacy above what you have in mind by the term?
 
This is usually referred to as the Transcendental Argument for the Existence of God =TAG].

Having a background in Aristotelian-Thomistic philosophy I all for philosophical arguments for the existence of God. So I asked myself what would Thomas say about TAG? As I understand the argument–and I am open to correction–I would have to say Thomas would give it a thumbs down. Why?

The short answer is this:
TAG characterizes inductive first principles or universal laws of thought as “logical absolutes,” as if they were infused into our intellect (or placed there innately) by God from platonic forms existing in the infinite mind of God; and then concludes from this characterization (the absolute, “divine,” and independent existence of these logical forms) that the infinite mind of God exists. This seems circular.
In order to use language/speech correctly you have to adhere to the universal laws of logic unless of course you want to be irrational and sound like a blabbering fool. Take the law of non-contradiction for example. If I make statements like this, – ‘God exists and God does not exists’ – ‘I am a Christian and Not a Christan’ – ‘I can be and not be’, they would all be False Statements! All those statements would be illogical because they would contradict themselves. They wouldn’t make sense so in order to make sense we must adhere to the universal laws of logic. When we adhere to the laws of logic we are rational and when we don’t we are irrational.
Good so far.
If the universal laws of logic exists then absolute truth exists. If absolute truth exists then God exists. The basic reasoning behind this is that you cannot give what you do not have, for example: I do not have a million dollars to give you therefore I cannot give you a million dollars. The universal laws of logic cannot be absolutely true by themselves they require a transcendent absolute truth (God) that can give these laws the essence to be absolutely true.
How did we get from “universal laws” to “absolute truth”? It seems you’re endowing an inductive generalization with a divine prerogative without proof, and then using that divine prerogative as evidence that God exists. This is circular.

That is, first principles are seen inductively by the human intellect to be true and inherent in all correct reasoning about being. Going further and calling them “absolutely true” is to sneak in a synonym for God or for infused knowledge by God or a divine platonic form or a divine characteristic. To then go on and say in essence “something divine needs a divine cause; ergo, God exists” is circular.
*If God does not exists then the laws of logic are not absolutely true then I have absolutely no reason to obey them therefore I do not have to be rational, nor does anybody else. We know that we ‘ought’ to be rational therefore we appeal to the universal laws of logic proving absolute truth exists therefore proving God exists.
Every-time you think/talk/write you are using Gods absolute universal truths of logic therefore proving Gods existence, even when you are illogical. *
I would also say the laws of logic exist just like mathematics exist. We are simply discovering them. They are hardwired into us as humans beings (mind and spiritual soul). Technically, it’s not even our logic, it’s Gods logic and we are simply borrowing it.
This would be another philosophical proof, a reductio ad absurdum. But first of all, if God does not exist, nothing exists. So what I think you really mean is “if one does not believe that God exists” or “if one has not yet proven that God exists.” However, even in those conditions first principles are still valid inductive, intuitive truths that are evident to the intellect and whose truth is seen as soon as their meaning is grasped. We ignore and deny them at our peril. That is, rooted in truth as correspondence there is also the pragmatic nature of truth: truth and rationality are what work; falsehood and irrationality don’t and can kill us. Barring the mentally ill, nobody signs up for that. This is where the “ought” resides until God’s existence is proven. Further we don’t need a reason to obey the laws of logic and rationality, because by your definition we already do–we just discover them. . . inductively. I don’t think you have shown the absurdum: a contradiction, self-contradiction, falsehood, or an implausibility or anomaly.
 
For more detail and background, I can’t see how TAG succeeds for the following reasons.

Method
(1) The subject under debate is whether or not God exists.
(2) Since it is an attempt to demonstrate the existence of God, it has to be a philosophical proof, i.e., it seeks to demonstrate the existence of God by the natural light of reason thus excluding assertions derived from divine revelation.
(3) TAG is offered in support of an affirmative conclusion: that the existence of God (not a definition of God) has been proven by TAG.

“Logical Absolutes” and their Source
The examples of “logical absolutes” or “universal laws of logic” given are really just first principles, also at times called by the Philosopher (Aristotle) “primary immediate premises.” These are not innate, not infused, nor are they arrived at by deduction. They are evident (or “self-evident” as some say) because they are seen to be true directly, intuitively from our experience of the world and so do not require proof. But, again, they do require experience of the world . . . of the physical world. They are the result of induction. Nothing is in the intellect that was not first in the senses–this is the path and condition of possibility for human knowledge.

“Indeed, all the proper principles of any science depend on first indemonstrable principles, which are self-evident, and we get our knowledge of these from the senses, as is shown at the end of the Posterior Analytics.”
[St. Thomas Aquinas, *Summa Contra Gentiles III, 41, 11] see also De Veritate VIII, 15; X, 6; X, 13.

First principles are: “the first conceptions of the intellect which are known at once by the light of the agent intellect through species abstracted from sensible objects.” [St. Thomas Aquinas, *De Veritate XI, 1]

Truth
They are also called true; and, given that they are called “absolute truths,” they must be held to be true always even if the universe would cease to exist.

What does it mean to say they are “true”? As Aristotle pointed out “The true and the false are not in things but in the mind.” (Metaphysics VI, 4 1027b26) And as explained in De Veritate “truth is conformity of thing and intellect.” ( I, 2) Truth is a relationship. . . a relationship of conformity of intellect with thing. “True expresses the correspondence of being to the knowing power, for all knowing is produced by an assimilation of the knower to the thing known, so that assimilation is said to be the cause of knowledge.” (De Veritate I, 1)

But, at this stage of our human philosophical proof, if we suppose that the universe ceased to exist, there would be no thing, no intellect, no relationship between the two, and therefore no truth. There would be simply nothing.

Status of the Question
Consequently, philosophically speaking, since we are attempting to prove the existence of God, so far–

• If the universe and/or the human mind did not exist, ditto for “LAs” (first principles really) and the conditions necessary for truth because there would no longer be a knower and/or a thing known.
• First principles are dependent on the material world.
• First principles are dependent on human nature: our concepts are derived from sense experience. We are not angels.
• First principles are dependent on the relational nature of truth.
 
Philosophically, the argument from authority is the weakest argument since assent in philosophy is based on publically available evidence: direct observation/experience, self-evident truths, or reasoned argument from them.

But theology is based on the word of God apprehended and assented to in faith; and so arguments in theology are based on the word of God as the authority. However it is possible to show demonstratively that supposed contradictions in the Faith or to the Faith are not necessary.

Aristotle distinguished formal fallacies, fallacies in language, and material fallacies. Material fallacies are fallacies outside of language in the matter of the argument, i.e., in the reasoning process itself. Examples would be the different permutations of Irrelevant Conclusion, ad hominem arguments, guilt by association, loaded term, etc.

In other words regarding material fallacies, Aristotle would hold you’re not thinking straight if you think that by attacking the person you have refuted their argument.

Some logicians now include a separate category, Inductive Fallacies, like False Generalization, False Cause, Common Cause, Confounding Variables, etc.

Is the definition of Material Fallacy above what you have in mind by the term?
Thanks for the (name removed by moderator)ut.

I share the same ideas regarding material fallacies that you do. But do I have the same logical ideas, that is, philosophy of logic? I think logic is supposed to be a very formalistic and systematic presentation of inferences; a blueprint for thinking. I think that the ideal of logic is symbolic logic and predicate calculus.

But this is why I was wondering how logicians could define something like “clear thinking” except only in the most abstract quasi-mathematical sense; for this definition must ultimately be a material conclusion reached from formal premises.

However, I earlier wanted to explore if my conception of the division between material and formal was really true. To me the formal fallacies were only fallacies since they were improperly connected propositions much like if one were to improperly piece together a puzzle. But the material fallacies were like psychological statements and statements of fact which could not be violated no matter the form in which they were expressed. But are these two really different? The formal fallacies are just as much statements of fact as the material ones are, and are in some sense, psychological phenomenon (insofar as someone reasoning badly would be called weak-minded). While the material fallacies are wrong because they lack purely formal connections with their conclusions (as when I might say, derek is bad so derek is wrong; there’s no middle step that helps you to go from premise to conlcusion).

So are they really that different or what comes to the same, am I getting their differences truthfully? What else might Aristotle say about this?
 
I understood all that, but I just don’t understand how this connects with the material fallacies of logic which all seem, to me, to be criticisms of the content of what is being said.
I think, in a way, formal fallacies are criticisms of the content of an argument when a certain premise is employed that has been used over and over again in the course of logic and has been regularly shown to be a false premise. Moreover, such a premise is usually implicit.

In the example you gave concerning the argument to authority, implicit in every fallacious argument to authority is the premise that either (1) the authority you’re citing is an expert in a relevant field, or (2) expert authorities are infallible. Your opponent will rightfully call you out for making such a fallacious argument when you use an irrelevant authority figure to argue your point, or when you argue in such a manner which gives the appearance that your conclusion must be certain given the authority with which it was argued.

Let’s use some examples again.

P1: Al Gore declares that anthropogenic climate change is real,
C: Anthropogenic climate change is real.

I’ve argued fallaciously here since implicit in my argument is that Al Gore is an expert in climatology, and this is a false premise.

P2: Phil Jones (an actual, famous climatologist) says that anthropogenic climate change is real,
C: Anthropogenic climate change is real.

I’ve again argued fallaciously, but this time the cause of the fallacy is the implicit premise that any given climate scientist is free from error.

P3: The majority of climatologists agree that anthropogenic climate change is real,
C: Anthropogenic climate change is most likely real.

This time I have a non-fallacious appeal to authority. Recognizing that I myself am not academically qualified to judge climatological data, I’m appropriately deferring to the experts as an entire corpus. In this argument, I haven’t assumed that any one person is infallible nor have I used “experts” that aren’t truly experts in the field.
God is infallible
Infallible people should be believed
You should believe anything God says (because he said it)
Is also a formally valid argument and some might say a sound argument too. But yet it falls victim to the fallacy of “argument from authority” in that anyone who believes it necessarily believes in the validity of the invalid “argument from authority” style.
In this case I’d say that God, by definition, is the exception to the taken-for-granted premise that no human is infallible, and so this is not a fallacious appeal to authority.
 
Thanks for the (name removed by moderator)ut.

I share the same ideas regarding material fallacies that you do. But do I have the same logical ideas, that is, philosophy of logic? I think logic is supposed to be a very formalistic and systematic presentation of inferences; a blueprint for thinking. I think that the ideal of logic is symbolic logic and predicate calculus.

But this is why I was wondering how logicians could define something like “clear thinking” except only in the most abstract quasi-mathematical sense; for this definition must ultimately be a material conclusion reached from formal premises.

However, I earlier wanted to explore if my conception of the division between material and formal was really true. To me the formal fallacies were only fallacies since they were improperly connected propositions much like if one were to improperly piece together a puzzle. But the material fallacies were like psychological statements and statements of fact which could not be violated no matter the form in which they were expressed. But are these two really different? The formal fallacies are just as much statements of fact as the material ones are, and are in some sense, psychological phenomenon (insofar as someone reasoning badly would be called weak-minded). While the material fallacies are wrong because they lack purely formal connections with their conclusions (as when I might say, derek is bad so derek is wrong; there’s no middle step that helps you to go from premise to conlcusion).

So are they really that different or what comes to the same, am I getting their differences truthfully? What else might Aristotle say about this?
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?
 
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