A fallacy is flawed reasoning. For instance, if one concludes that a math proof is correct, not on the merits of the steps of the proof, but because a famous mathematician is providing it, the reasoning is clearly flawed by an appeal to authority. Famous mathematicians can and do make mistakes, and the nature of mathematical proof rests in the consistency of the logic from step to step.

A cognitive bias is systematic error-making in thinking. Let's say you are doing research, but after your PhD advisor looks at your sources, it becomes clear that you are drawing from one set of papers that supports your thesis, while there's an entire set of papers that refutes your thesis. It might be that your choice to do so is consistent with the fact that you routinely avoid any positions critical of your position. In some way, you are confirming your belief through a non-conscious selection of avoiding evidence avoiding disconfirmation.

Both bias and fallacies are types of errors, but a bias is a pattern of making a similar error, and fallacies are errors that apply to a given argument. In other words, fallacies are individual, logical errors in reason, whereas cognitive biases are consistent, psychological errors in thinking.

EDIT

To address claims in the comments: Biases might cause fallacies, but the important thing about biases is that they are systematic. Everybody makes mistakes errors in reason, but one who does consistently in the same way is biased, and it's important not to conflate the two. Think about lies, and pathological liars. Some people tell lies from time to time, but those who do so with zest, zeal, and compulsion are fundamentally different. And biases aren't what we want to believe, they are what we tend to believe erroneously. I personally have biases, but in a bid to improve my reason very much work hard because I don't want to believe error-riddled reasoning. Many people are comfortable with their biases, but many people work hard to overcome them precisely because they want to be closer to being free of errors.

Answer from J D on Stack Exchange
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Daytonastate
library.daytonastate.edu › reliable › logicalfallacies
Bias, Preconceptions, and Logical Fallacies - Finding Reliable Information - DSC Library at Daytona State College
1 month ago - Implementing strategies such as ... on research outcomes. Logical fallacies are errors in reasoning that can undermine the validity and soundness of arguments or conclusions....
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Doctor Spin
doctorspin.org › home › online creative › storytelling & writing › twin peaks season 3 finale explained (spoiler alert)
58 logical fallacies and cognitive biases - Doctor Spin
Therefore, they will be biased towards stories that fit with the reigning narrative — a sort of amplification of the agenda-setting theory. “We’ve got the best player in the world on our team, so we must also have the best team in the world.” · Just because something is true for the whole, that doesn’t also make it true for the parts. This is the opposite to the fallacy of composition. For instance, just because a religion as a whole are advocating peace and kindness, that doesn’t mean that significant parts of the religion can’t be violent.
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logic - Difference between fallacies and biases - Philosophy Stack Exchange
What is the basic difference between biases, such as confirmation bias, anchoring bias, etc., and fallacies such as argumentum ad antiquitatem, argumentum ad hominem, argumentum ad ignorantiam, etc... More on philosophy.stackexchange.com
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Has the relationship between cognitive biases and logical fallacies been studied?
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Guide to Logical Fallacies and Cognitive Bias

Well I'd definitely believe this chart, but the OP is almost certainly an unmarried hussy who eats their own boogers.

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Good books on biases, logical fallacies and cognitive distortions?
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Why are fallacies misleading?
Fallacies are arguments that contain some type of reasoning error. Regardless of whether they are used intentionally or by error, they weaken an argument by using erroneous beliefs, illogical arguments, or deception. · As a result, they shift the focus of a discussion to unrelated topics or side issues and can thus be misleading. For example, the genetic fallacy shifts the attention to the source or origin of an argument instead of presenting evidence to refute the argument itself.
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What are fallacies of relevance?
Fallacies of relevance are a group of fallacies that occur in arguments when the premises are logically irrelevant to the conclusion. Although at first there seems to be a connection between the premise and the conclusion, in reality fallacies of relevance use unrelated forms of appeal. · For example, the genetic fallacy makes an appeal to the source or origin of the claim in an attempt to assert or refute something.
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What is the difference between the ad hominem fallacy and the genetic fallacy?
The ad hominem fallacy and the genetic fallacy are closely related in that they are both fallacies of relevance. In other words, they both involve arguments that use evidence or examples that are not logically related to the argument at hand. However, there is a difference between the two: · In the ad hominem fallacy, the goal is to discredit the argument by discrediting the person currently making the argument. · In the genetic fallacy, the goal is to discredit the argument by discrediting the history or origin (i.e., genesis) of an argument.
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Wichita State University
wichita.edu › services › mrc › OIR › Pedagogy › Theories › cognitivebias.php
Cognitive Bias
The distinction between a logical fallacy and a cognitive bias is that cognitive biases are rooted in the way the brain actually works whereas logical fallacies are errors in argument. Learners can be trained to avoid logical fallacies, but cognitive biases are trickier.
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TeachThought
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The Difference Between Logical Fallacies And Cognitive Biases | TeachThought
October 25, 2025 - ... In short, logical fallacies and cognitive biases are both failures of reason–errors in thinking that can result in inaccurate perspectives, distorted views, error-filled judgments, and eventually, skewed, irrational beliefs (about one’s ...
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HKU Philosophy
philosophy.hku.hk › think › fallacy
[F] Fallacies and biases
Fallacies are mistakes of reasoning, as opposed to making mistakes that are of a factual nature. Biases are persistant and widespread psychological tendencies that can be detrimental to objectivity and rationality. Being aware of them can help us avoid their influence.
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Hive Mind
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Cognitive Biases and Logic Pitfalls: Behind Reasoning and Decision-Making | Publications & Media | Hive Mind
Logical fallacies and cognitive bias go hand in hand. It takes critical thinking skills and positive self-doubt to avoid these traps that contribute to stereotyping, stigmatization, misrepresentation, and other negative outcomes of the lack ...
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Your Logical Fallacy Is
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Thou shalt not commit logical fallacies
Get a deck of these pretty great high quality cards featuring 24 logical fallacies and 24 cognitive biases, as well as 3 game cards.
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A fallacy is flawed reasoning. For instance, if one concludes that a math proof is correct, not on the merits of the steps of the proof, but because a famous mathematician is providing it, the reasoning is clearly flawed by an appeal to authority. Famous mathematicians can and do make mistakes, and the nature of mathematical proof rests in the consistency of the logic from step to step.

A cognitive bias is systematic error-making in thinking. Let's say you are doing research, but after your PhD advisor looks at your sources, it becomes clear that you are drawing from one set of papers that supports your thesis, while there's an entire set of papers that refutes your thesis. It might be that your choice to do so is consistent with the fact that you routinely avoid any positions critical of your position. In some way, you are confirming your belief through a non-conscious selection of avoiding evidence avoiding disconfirmation.

Both bias and fallacies are types of errors, but a bias is a pattern of making a similar error, and fallacies are errors that apply to a given argument. In other words, fallacies are individual, logical errors in reason, whereas cognitive biases are consistent, psychological errors in thinking.

EDIT

To address claims in the comments: Biases might cause fallacies, but the important thing about biases is that they are systematic. Everybody makes mistakes errors in reason, but one who does consistently in the same way is biased, and it's important not to conflate the two. Think about lies, and pathological liars. Some people tell lies from time to time, but those who do so with zest, zeal, and compulsion are fundamentally different. And biases aren't what we want to believe, they are what we tend to believe erroneously. I personally have biases, but in a bid to improve my reason very much work hard because I don't want to believe error-riddled reasoning. Many people are comfortable with their biases, but many people work hard to overcome them precisely because they want to be closer to being free of errors.

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Scribbr
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What is the difference between cognitive bias and logical fallacy?
April 20, 2023 - Cognitive bias refers to an ongoing predisposition, while logical fallacy refers to mistakes of reasoning that occur in the moment.
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Reddit
reddit.com › r/asksocialscience › has the relationship between cognitive biases and logical fallacies been studied?
r/AskSocialScience on Reddit: Has the relationship between cognitive biases and logical fallacies been studied?
June 1, 2022 -

[Edit for the !remindme folks: I more-or-less managed to answer my own question, with some "help" from Garblin. In the process of finding stand-alone studies on fallacies to demonstrate that yes, they CAN be studied scientifically, I came across the critical thinking literature, which overlaps with research on both cognitive biases and logical fallacies. I haven't quite found what I was originally looking for yet, but I'm pretty confident that it's here if it's anywhere, so I'm going to spend some time exploring the web of which critical thinking articles cite and are cited by others.]

I'm familiar with cognitive biases and logical fallacies independently, but I've found surprisingly little that directly connects the two concepts. It seems reasonable at first glance to expect that informal logical fallacies A/B/C are prevalent in society due to cognitive biases X/Y/Z: writers/speakers who have those biases will make accidentally fallacious arguments (and bad actors will make intentionally fallacious ones), and readers/listeners who have those biases will be persuaded by them, reinforcing the cycle. For example:

  • The halo/horn effect biases make the ad hominem fallacy effective

  • The anchoring bias makes the anecdotal fallacy effective

  • The apophenia bias makes the false cause fallacy effective

  • The groupthink bias makes the bandwagon/appeal to popularity fallacy effective

The vast majority of sources I've found on biases and fallacies tends to treat them separately though. For example, most of my links above are from two projects by the same organization (The School of Thought) that never draw connections between the two categories, despite presumably being created by the same team.

If I explicitly search for both terms together on Google Scholar or regular Google and weed out the majority of articles that focus on the differences between them, there are a few articles in line with the ideas above, although they're not written by experts in the field and don't cite any literature on the connection between biases and fallacies:

Perception and Persuasion in Legal Argumentation: Using Informal Fallacies and Cognitive Biases to Win the War of Words

To use a simple analogy, informal fallacies and cognitive biases are two sides of the same coin-one side that represents faulty verbal or written reasoning, and one side that represents faulty mental reasoning.

(regarding the tile: ewww)

Logical Fallacy vs Cognitive Bias – What Is The Difference Between Them?

As mentioned earlier, the important difference between biases and fallacies is that biases affect how you interpret and process information, and fallacies relate to how you construct your arguments and communicate your ideas.

This means that they are closely related to each other; a cognitive bias is often the inclination to commit a logical fallacy in an argument.

Has there been any peer-reviewed research connecting cognitive biases and informal logical fallacies (e.g. testing whether people who display high levels of a particular bias in one context will be more likely to make or be persuaded by arguments with a conceptually related fallacy in a different context), or have any educational/pop science sources gone into more depth on the relationship between them?

If nothing else, this seems like teaching them hand-in-hand could be a good framework for promoting introspection and self-improvement by using justified concerns about manipulation as a hook: "Hey, did you know those so-and-sos are tricking you into acting against your best interests using these sneaky tactics, which oh by the way are so effective because of these quirks in how our brains work..."

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random citation here to keep the auto-mod from auto-modding this I'm not sure there really can be science done on this one, and it's a fundamental issue with how you're trying to get two fields to interact. Logical fallacies are from the Logic subset of Philosophy. Logic was a precursor to a lot of things like math and science, but it's still a bunch of words, not data. Like all of philosophy, it's a bunch of ways of thinking about things that, at least ideally, are useful to us. Cognitive Biases on the other hand are errors in thinking that psychology has been able to collect data and evidence on and classify into groups. It's rooted in science. You're dealing with similar concepts that are rooted in two entirely different approaches to gaining truth in the universe. Philosophy can be (oversimplified) considered "making as much sense of the universe through sheer force of will and intelligence as possible" while science can be (again oversimplified) considered "using thorough methodology to create and test hypotheses about the universe to gain increasingly accurate approximations of the truth about the universe". Obviously there's going to be overlap in what folks come up with in the two ways, but because Logical Fallacies aren't a scientific idea (regardless of their truth) you can't really research them. We can point to cognitive biases and say "ah hah! here's the scientific fact of why we engage in those fallacies" but the fallacies themselves aren't really themselves study-able. I feel like I'm talking in circles with this and not getting any clearer, so Imma stop here, but happy to try and converse to clarify.
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Rozenbergquarterly
rozenbergquarterly.com › issa-proceedings-2014-cognitive-biases-and-logical-fallacies
ISSA Proceedings 2014 – Cognitive Biases And Logical Fallacies : Rozenberg Quarterly
Cognitive psychology identifies several dozen cognitive biases, which are “replicable pattern(s) in perceptual distortion, inaccurate judgment, illogical interpretation, or what is broadly called irrationality[i]”. (This and other quotations that describe cognitive biases below are taken from the Wikipedia list of cognitive biases; see Footnote 2.) I think argumentation scholars should incorporate these findings of cognitive psychology into their research for several reasons. First, some cognitive biases resonate well with the logical fallacies argumentation theorists know of, and to no surprise: both are, in fact, improper reasoning patterns that occur systematically.
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Aupress
read.aupress.ca › read › critical-thinking-logic-and-argument › section › 41da2ac7-5780-47fa-b3f5-3d88edd368eb
Chapter 13. Introduction to Fallacies and Bias | Critical Thinking, Logic, and Argument | AU Press—Digital Publications
... • A fallacy, in the strict sense, is a form of argument that is invalid or else violates a relevance condition. • Fallacies appear in arguments—that is, they appear in the transition from a set of premises to a conclusion (which can contain a fallacy).
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Portland Community College
pcc.edu › library › toolkit › 12-cognitive-biases-explained-how-to-think-better-and-more-logically-removing-bias
12 Cognitive Biases Explained – How to Think Better and More Logically Removing Bias - PCC Library
Cognitive biases are flaws in logical thinking that clear the path to bad decisions, so learning about these ideas can reduce errors in your thought process, leading to a more successful life. These biases are very closely related to logical fallacies, which may help you win an argument or ...
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Touchstonetruth
touchstonetruth.com › four-mind-traps-logical-fallacies-cognitive-bias-heuristics-stereotypes
4 Mind Traps: Fallacies, Biases, Heuristics, and Stereotypes | TouchstoneTruth.com
May 12, 2023 - Logical fallacies, cognitive biases, heuristics, and stereotypes are grouped together as Mind Traps because they share a commonality in their ability to distort our thinking and lead us away from a clear and accurate understanding of the world.
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Quora
quora.com › What-is-the-difference-between-logical-fallacy-and-bias
What is the difference between logical fallacy and bias? - Quora
Answer (1 of 8): Bias is a predetermined response to a stimulus based on your exposure to an environment; it can be a physical bias, an emotional bias, or a social bias. Ex. I don’t like the color blue; you are disqualifying the color blue without stating a reason or rationale.
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Sketchplanations
sketchplanations.com › cognitive-bias-heuristic-logical-fallacy
Cognitive bias, heuristic, logical fallacy: hidden features of the mind - Sketchplanations
July 19, 2024 - Things like social proof, how if others seem to like something that’s a shortcut for "we’ll probably like it." A logical fallacy is a flaw in our reasoning, leading to a faulty argument.
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Forbes
forbes.com › sites › glebtsipursky › 2023 › 05 › 13 › cognitive-distortions-unconscious-bias-cognitive-bias-logical-fallacies-what-you-need-to-know-to-protect-yourself
Cognitive Distortions, Unconscious Bias, Cognitive Bias, Logical Fallacies: What You Need To Know To Protect Yourself
April 20, 2023 - Now, cognitive biases make us vulnerable to manipulation by logical fallacies. For example, the cognitive bias known as attentional bias, our tendency to pay attention to the most emotionally salient features of our environment, contributes to our frequent failure to notice the vast amount of evidence available from which an underhanded debater cherry-picks their points. One of the side benefits of studying cognitive biases is that doing so helps us avoid being manipulated by advertisers, politicians, and other skilled manipulators.
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Wikipedia
en.wikipedia.org › wiki › List_of_fallacies
List of fallacies - Wikipedia
3 days ago - Argument from fallacy (also known as the fallacy fallacy) – the assumption that, if a particular argument for a "conclusion" is fallacious, then the conclusion by itself is false. Base rate fallacy – making a probability judgement based on conditional probabilities, without taking into account the effect of prior probabilities. Conjunction fallacy – the assumption that an outcome simultaneously satisfying multiple conditions is more probable than an outcome satisfying a single one of them. Non sequitur fallacy – where the conclusion does not logically follow from the premise.
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Quora
quora.com › What-is-the-difference-between-cognitive-biases-and-logical-fallacies
What is the difference between cognitive biases and logical fallacies? - Quora
Answer (1 of 4): Logical fallacies are errors in reasoning which means that a line of argumentation is faulty. This is on account of its premises being defective, or the conclusion not following from the premises.