15 Common Logical Fallacies

1) The Straw Man Fallacy

This fallacy occurs when your opponent over-simplifies or misrepresents your argument (i.e.,
setting up a "straw man") to make it easier to attack or refute. Instead of fully addressing
your actual argument, speakers relying on this fallacy present a superficially similar -- but
ultimately not equal -- version of your real stance, helping them create the illusion of easily
defeating you.

2) The Bandwagon Fallacy

Just because a significant population of people believe a proposition is true, doesn't

automatically make it true. Popularity alone is not enough to validate an argument, though it's
often used as a standalone justification of validity. Arguments in this style don't take into
account whether or not the population validating the argument is actually qualified to do so, or
if contrary evidence exists.

While most of us expect to see bandwagon arguments in advertising (e.g., "three out of four
people think X brand toothpaste cleans teeth best"), this fallacy can easily sneak it's way into
everyday meetings and conversations.

3) The Appeal to Authority Fallacy

While appeals to authority are by no means always fallacious, they can quickly become
dangerous when you rely too heavily on the opinion of a single person -- especially if that
person is attempting to validate something outside of their expertise.

Getting an authority figure to back your proposition can be a powerful addition to

an existing argument, but it can't be the pillar your entire argument rests on. Just because
someone in a position of power believes something to be true, doesn't make it true.

4) The False Dilemma Fallacy

This common fallacy misleads by presenting complex issues in terms of two inherently opposed
sides. Instead of acknowledging that most (if not all) issues can be thought of on a spectrum of
possibilities and stances, the false dilemma fallacy asserts that there are only two mutually
exclusive outcomes.

This fallacy is particularly problematic because it can lend false credence to extreme stances,
ignoring opportunities for compromise or chances to re-frame the issue in a new way.

5) The Hasty Generalization Fallacy

This fallacy occurs when someone draws expansive conclusions based on inadequate or
insufficient evidence. In other words, they jump to conclusions about the validity of a
proposition with some -- but not enough -- evidence to back it up, and overlook potential
counterarguments. 

6) The Slothful Induction Fallacy

Slothful induction is the exact inverse of the hasty generalization fallacy above. This fallacy
occurs when sufficient logical evidence strongly indicates a particular conclusion is true, but
someone fails to acknowledge it, instead attributing the outcome to coincidence or something
unrelated entirely.

7) The Correlation/Causation Fallacy

If two things appear to be correlated, this doesn't necessarily indicate that one of those things
irrefutably caused the other thing. This might seem like an obvious fallacy to spot, but it can be
challenging to catch in practice -- particularly when you really want to find a correlation
between two points of data to prove your point.

8) The Anecdotal Evidence Fallacy

In place of logical evidence, this fallacy substitutes examples from someone's personal
experience. Arguments that rely heavily on anecdotal evidence tend to overlook the fact that
one (possibly isolated) example can't stand alone as definitive proof of a greater premise.

9) The Texas Sharpshooter Fallacy

This fallacy gets its colorful name from an anecdote about a Texan who fires his gun at a barn
wall, and then proceeds to paint a target around the closest cluster of bullet holes. He then
points at the bullet-riddled target as evidence of his expert marksmanship.

Speakers who rely on the Texas sharpshooter fallacy tend to cherry-pick data clusters based on
a predetermined conclusion. Instead of letting a full spectrum of evidence lead them to a logical
conclusion, they find patterns and correlations in support of their goals, and ignore evidence
that contradicts them or suggests the clusters weren't actually statistically significant. 

10) The Middle Ground Fallacy

This fallacy assumes that a compromise between two extreme conflicting points is always true.
Arguments of this style ignore the possibility that one or both of the extremes could be
completely true or false -- rendering any form of compromise between the two invalid as well.

11) The Burden of Proof Fallacy

If a person claims that X is true, it is their responsibility to provide evidence in support of that
assertion. It is invalid to claim that X is true until someone else can prove that X  is not true.
Similarly, it is also invalid to claim that X is true because it's impossible to prove that X is false.

In other words, just because there is no evidence presented against something, that doesn't
automatically make that thing true.

12) The Personal Incredulity Fallacy

If you have difficulty understanding how or why something is true, that doesn't automatically
mean the thing in question is false. A personal or collective lack of understanding isn't enough
to render a claim invalid.

13) The "No True Scotsman" Fallacy

Often used to protect assertions that rely on universal generalizations (like "all Marketers love
pie") this fallacy inaccurately deflects counterexamples to a claim by changing the positioning
or conditions of the original claim to exclude the counterexample.

In other words, instead of acknolwedging that a counterexample to their original claim exists,
the speaker ammends the terms of the claim. In the example below, when Barabara presents a
valid counterexample to John's claim, John changes the terms of his claim to exclude Barbara's
counterexample.

14) The Tu quoque Fallacy
The tu quoque fallacy (Latin for "you also") is an invalid attempt to discredit an opponent by
answering criticism with criticism -- but never actually presenting a counterargument to the
original disputed claim. 

In the example below, Lola makes a claim. Instead of presenting evidence against Lola's claim,
John levels a claim against Lola. This attack doesn't actually help John succeed in proving
Lola wrong, since he doesn't address her original claim in any capacity.

15) The Fallacy Fallacy

Here's something vital to keep in mind when sniffing out fallacies: just because someone's
argument relies on a fallacy doesn't necessarily mean that their claim is inherently untrue.

Making a fallacy-riddled claim doesn't automatically invalidate the premise of the argument -- it

just means the argument doesn't actually validate their premise. In other words, their
argument sucks, but they aren't necessarily wrong.