There are a long list of variously titled fallacies, most with fancy Latin names and some that are arguably equivalent, which are often used in debates. To name a few:
argumentum ad baculum
argumentum ad nauseam
argumentum ad populum
argumentum ad ignorantiam
argumentum ad misericordiam
argumentum ad hominem
ignoratio elenchi
petitio principia
tu quoque
argumentum ad verecundiam
etc. What virtually all these "fallacies" have in common is that they are not necessarily fallacies at all:
"A standard definition of a fallacy that was accepted until recently is that of 'an argument that seems to be valid but that is not valid.' During the last few decades, however, argumentation theorists have raised several important objections to this definition: 'Seems' involves an undesirable amount of subjectivity; 'validity' is incorrectly presented as an absolute and conclusive criterion; the definition ignores the fact that some well-known fallacies are valid by the terms of present-day logical standards; the definition restricts the scope of the concept of fallacies to patterns of reasoning, leading to the exclusion of a large number of recognized fallacies."
Van Eemeren, F. H., & Grootendorst, R. (2004). A systematic theory of argumentation: The pragma-dialectical approach. Cambridge University Press.
As a simple example, take evolution. I can use the argument from ignorance against any supporter of evolution. If falsifiability is to be a part of the philosophy of science, in that theories must be capable of being shown to be false, then for any theory that hasn't been shown to be false, it is necessarily true that there is potential contradictory evidence that has not yet been found. As such, any theory is an "Argument from ignorance...where 'ignorance' stands for: 'lack of evidence to the contrary'" (from wiki). That "lack of evidence to the contrary" is the basis for the scientific framework: we do not prove theories correct, we merely strengthen the reason to think so. Yet few would argue all research is necessarily just arguments from ignorance.
Nor is an appeal to authority always a fallacy. If I say global warming is false because a professor at Cambridge with 3 PhDs says so, but that professor has never really looked into the evidence, then my argument is clearly a fallacy. Most would argue that even if I point out that some of the foremost climate scientists in the world have argued that there is not sufficient evidence for AGW, I may not be appealing to authority in the same way, but I am appealing to it in a way that the other side can as well (and more so). Finally, if I argue that the consensus is that global warming is real, am I arguing from authority? Well, yes. I am certainly not giving any evidence. But consensus is formed on the basis of research. It may be (and I believe is) formed by other things as well, and the consensus can be (and has been) wrong, but an appeal to academic consensus is an appeal to the work of experts over time on all the evidence we currently have for any argument, theory, theoretical framework, etc., and thus implicitly to evidence.
Which leads naturally to another fallacy. Let's say I appeal to academic consensus on the historical Jesus and that instead of the usual "appeal to authority" reply, I my argument is met with an attempt to "poison the well", a fallacy which is basically argumentum ad homines, or "argument against the people". For example, people might say that historical Jesus scholars are mostly Christian and therefore biased. Ok, but it may be that biologists are all biased against religion, or that climate scientists are tree-hugging hippies. And while it is hard to show that Christian bias would make Christians tend to support a historical Jesus (after all, if Jesus was historical but never rose from the dead, then the fact that he was historical is moot; there's no basis for Christianity), I can easily point to evidence of potentially damaging bias in climate science. But is there sufficient evidence that if this bias exists it has thrown in question the consensus view and/or view as suspect the research behind it? That would require a good argument, and when appeals to consensus are met with claims that the consensus is biased, rarely is evidence offered, still less evidence that the alleged bias damages the evidence upon which the consensus is based.
But perhaps in reply to my argument from authority I might get a fallacy of definition: someone might point out that most historical Jesus researchers not "historians".
I give you the dept. of history at the distinguished University of Columbia. The link breaks down faculty by time period. You'll notice that the first period is "To 400" which means "any history up to the year 400 CE". There are 6 scholars. If we add on another ~1000 years, we get another 8 names. If we look at the 19th & 20th centuries, we get many times this number. On the face of it, it would seem that an ivy league university thinks human history isn't all that important until around the 19th century, and certainly that anything before 400 CE isn't worth much investigation.
The real reason that the list is so small is because most historians of pre-400 CE are not people with degrees in history an the history department works in tandem with departments and scholars like those responsible for most historical Jesus research. It simply is not true to say that because someone has a PhD in NT/Biblical studies, one is not a historian. This is a definitional fallacy.
But there are times when this holds. For example, many people with doctorates in e.g., classics are philologists or linguists, not historians. Likewise, a biblical scholar might actually be a theologian, trained in hermeneutics and other things rather than historical methods.
Yet even then, it is not necessarily true that this disqualifies such an individual. How do scholars become experts in some field? By researching that field and publishing in it. Rand R Wilcox, the author of 2 of the best intro stats textbooks (they're better than many graduate level stats textbooks), has a PhD in psychometrics, not statistics. Yet he is a statistician. All four of his textbooks are in statistics. He's an editorial board member of prestigious journals like Computational Statistics and Data Analysis, a member of both the American Statistical Association and the Institute of Mathematical Statistics, and author of innumerable peer-reviewed studies on statistics.
But not all who have published in a field are experts in it. There is a professor of mathematics at Brown whom I grew up near. He has published a book on dynamical systems (and has lectured on dynamical systems). It was because of this that I sought his advice some years ago (that was a research interest of mine). However, his knowledge of dynamical systems theory was based in his specialty: number theory. So my neighbor was peripherally knowledgeable about limited aspects of dynamical systems, and not an expert.
The line can be fuzzy.
As a last example of when a fallacy isn't a fallacy is simple: Someone can be the meanest, most insulting debater known to humanity, but have a sound argument. It becomes argumentum ad hominem if the arguments are based on the insults, or the arguments are insufficient by themselves. I can prove that the square root of 2 is irrational, an although it would add 100 steps to my proof, I can throw in 100 insults against the person who disagrees and still be correct.
So when is a fallacy a fallacy? For some, fallacies are fallacies and shaking a fist is one; but for such people, typically a fallacy need not invalidate an argument. This doesn't help us much, but it points to the heart of the matter: what is the argument? If it seems to correspond to some fallacy, classical or modern, does it do so in the way the fallacy is understood to invalidate the argument? For example, if I argue that someone who insults me is relying the fallacy argumentum ad hominem, the question is not whether they are insulting me but whether they are relying on insulting me. They might call me an idiot, say I have no clue, and even combine insults with other fallacies like "everyone knows this" or "only someone as uninformed as you" when talking to me, in an email, in a forum post, etc. (and they might be right, yet this is still not evidence for their position). But if, amongst all these insults, they offer a sound argument, then it doesn't matter how many insults they use (at least with respect to whether their argument is based on fallacies; violating forum rules, for example, is of course a separate but no less important matter).
Bottom line:
Before flying back at someone by accusing them of having committed some fallacy, try to determine 2 things:
1) What is it about this fallacy that makes it a fallacy
&
2) Is it this aspect upon which their argument is built, and if so in what way (i.e., if you were to try to reconstruct the same underlying logic but apply to something you agree with, might you yourself find it more convincing in that case)?
argumentum ad baculum
argumentum ad nauseam
argumentum ad populum
argumentum ad ignorantiam
argumentum ad misericordiam
argumentum ad hominem
ignoratio elenchi
petitio principia
tu quoque
argumentum ad verecundiam
etc. What virtually all these "fallacies" have in common is that they are not necessarily fallacies at all:
"A standard definition of a fallacy that was accepted until recently is that of 'an argument that seems to be valid but that is not valid.' During the last few decades, however, argumentation theorists have raised several important objections to this definition: 'Seems' involves an undesirable amount of subjectivity; 'validity' is incorrectly presented as an absolute and conclusive criterion; the definition ignores the fact that some well-known fallacies are valid by the terms of present-day logical standards; the definition restricts the scope of the concept of fallacies to patterns of reasoning, leading to the exclusion of a large number of recognized fallacies."
Van Eemeren, F. H., & Grootendorst, R. (2004). A systematic theory of argumentation: The pragma-dialectical approach. Cambridge University Press.
As a simple example, take evolution. I can use the argument from ignorance against any supporter of evolution. If falsifiability is to be a part of the philosophy of science, in that theories must be capable of being shown to be false, then for any theory that hasn't been shown to be false, it is necessarily true that there is potential contradictory evidence that has not yet been found. As such, any theory is an "Argument from ignorance...where 'ignorance' stands for: 'lack of evidence to the contrary'" (from wiki). That "lack of evidence to the contrary" is the basis for the scientific framework: we do not prove theories correct, we merely strengthen the reason to think so. Yet few would argue all research is necessarily just arguments from ignorance.
Nor is an appeal to authority always a fallacy. If I say global warming is false because a professor at Cambridge with 3 PhDs says so, but that professor has never really looked into the evidence, then my argument is clearly a fallacy. Most would argue that even if I point out that some of the foremost climate scientists in the world have argued that there is not sufficient evidence for AGW, I may not be appealing to authority in the same way, but I am appealing to it in a way that the other side can as well (and more so). Finally, if I argue that the consensus is that global warming is real, am I arguing from authority? Well, yes. I am certainly not giving any evidence. But consensus is formed on the basis of research. It may be (and I believe is) formed by other things as well, and the consensus can be (and has been) wrong, but an appeal to academic consensus is an appeal to the work of experts over time on all the evidence we currently have for any argument, theory, theoretical framework, etc., and thus implicitly to evidence.
Which leads naturally to another fallacy. Let's say I appeal to academic consensus on the historical Jesus and that instead of the usual "appeal to authority" reply, I my argument is met with an attempt to "poison the well", a fallacy which is basically argumentum ad homines, or "argument against the people". For example, people might say that historical Jesus scholars are mostly Christian and therefore biased. Ok, but it may be that biologists are all biased against religion, or that climate scientists are tree-hugging hippies. And while it is hard to show that Christian bias would make Christians tend to support a historical Jesus (after all, if Jesus was historical but never rose from the dead, then the fact that he was historical is moot; there's no basis for Christianity), I can easily point to evidence of potentially damaging bias in climate science. But is there sufficient evidence that if this bias exists it has thrown in question the consensus view and/or view as suspect the research behind it? That would require a good argument, and when appeals to consensus are met with claims that the consensus is biased, rarely is evidence offered, still less evidence that the alleged bias damages the evidence upon which the consensus is based.
But perhaps in reply to my argument from authority I might get a fallacy of definition: someone might point out that most historical Jesus researchers not "historians".
I give you the dept. of history at the distinguished University of Columbia. The link breaks down faculty by time period. You'll notice that the first period is "To 400" which means "any history up to the year 400 CE". There are 6 scholars. If we add on another ~1000 years, we get another 8 names. If we look at the 19th & 20th centuries, we get many times this number. On the face of it, it would seem that an ivy league university thinks human history isn't all that important until around the 19th century, and certainly that anything before 400 CE isn't worth much investigation.
The real reason that the list is so small is because most historians of pre-400 CE are not people with degrees in history an the history department works in tandem with departments and scholars like those responsible for most historical Jesus research. It simply is not true to say that because someone has a PhD in NT/Biblical studies, one is not a historian. This is a definitional fallacy.
But there are times when this holds. For example, many people with doctorates in e.g., classics are philologists or linguists, not historians. Likewise, a biblical scholar might actually be a theologian, trained in hermeneutics and other things rather than historical methods.
Yet even then, it is not necessarily true that this disqualifies such an individual. How do scholars become experts in some field? By researching that field and publishing in it. Rand R Wilcox, the author of 2 of the best intro stats textbooks (they're better than many graduate level stats textbooks), has a PhD in psychometrics, not statistics. Yet he is a statistician. All four of his textbooks are in statistics. He's an editorial board member of prestigious journals like Computational Statistics and Data Analysis, a member of both the American Statistical Association and the Institute of Mathematical Statistics, and author of innumerable peer-reviewed studies on statistics.
But not all who have published in a field are experts in it. There is a professor of mathematics at Brown whom I grew up near. He has published a book on dynamical systems (and has lectured on dynamical systems). It was because of this that I sought his advice some years ago (that was a research interest of mine). However, his knowledge of dynamical systems theory was based in his specialty: number theory. So my neighbor was peripherally knowledgeable about limited aspects of dynamical systems, and not an expert.
The line can be fuzzy.
As a last example of when a fallacy isn't a fallacy is simple: Someone can be the meanest, most insulting debater known to humanity, but have a sound argument. It becomes argumentum ad hominem if the arguments are based on the insults, or the arguments are insufficient by themselves. I can prove that the square root of 2 is irrational, an although it would add 100 steps to my proof, I can throw in 100 insults against the person who disagrees and still be correct.
So when is a fallacy a fallacy? For some, fallacies are fallacies and shaking a fist is one; but for such people, typically a fallacy need not invalidate an argument. This doesn't help us much, but it points to the heart of the matter: what is the argument? If it seems to correspond to some fallacy, classical or modern, does it do so in the way the fallacy is understood to invalidate the argument? For example, if I argue that someone who insults me is relying the fallacy argumentum ad hominem, the question is not whether they are insulting me but whether they are relying on insulting me. They might call me an idiot, say I have no clue, and even combine insults with other fallacies like "everyone knows this" or "only someone as uninformed as you" when talking to me, in an email, in a forum post, etc. (and they might be right, yet this is still not evidence for their position). But if, amongst all these insults, they offer a sound argument, then it doesn't matter how many insults they use (at least with respect to whether their argument is based on fallacies; violating forum rules, for example, is of course a separate but no less important matter).
Bottom line:
Before flying back at someone by accusing them of having committed some fallacy, try to determine 2 things:
1) What is it about this fallacy that makes it a fallacy
&
2) Is it this aspect upon which their argument is built, and if so in what way (i.e., if you were to try to reconstruct the same underlying logic but apply to something you agree with, might you yourself find it more convincing in that case)?
