Logical Fallacies

Logical Fallacies:
Logical fallacies are tricks the human mind can play on itself. These tricks make things seem true or sensible when, if fact, they aren't.
This is a simplified version of a list from here http://www.theskepticsguide.org/resources/logical-fallacies

The italicized areas are my additions. These are not intended to alter the list’s meaning in any way, merely to make the list accessible to a wider audience.

Ad hominem:
An ad hominem argument is any that attempts to counter another’s claims or conclusions by attacking the person, rather than addressing the argument itself. Someone may suggest for example that a statement by Adolf Hitler was untrue just because Hitler was a murderer and racist; however, if Hitler said, "the ocean has a lot of fish in it," this would still be true despite his being a horrible monster.

Ad Ignorantiam:
The argument from ignorance basically states that a specific belief is true because we don’t know that it isn’t true such as ghosts must be real because we don’t have any proof that they aren’t. 

Argument from Authority:
Often this argument is implied by emphasizing the many years of experience, or the formal degrees held by the individual making a specific claim. The converse of this argument is sometimes used, that someone does not possess authority, and therefore their claims must be false. Experience and education certainly help; however, experts aren’t always right, and amateurs aren’t always wrong.

Argument from Final Consequences
Such arguments (also called teleological) are based on a reversal of cause and effect, because they argue that something is caused by the ultimate effect that it has, or purpose that is serves. Christian creationists have argued, for example, that evolution must be wrong because if it were true it would lead to immorality. 

Argument from Personal Incredulity:
This argument can be summarized, "I cannot explain or understand this; therefore, it cannot be true." People who are against homosexual marriage, for example, often make statements like "Why would anyone want to do that?" They can’t understand the lifestyle; therefore, they assume that it’s wrong. 

Bandwagon:
The bandwagon fallacy suggests that a premise must be true or a cause just because many people believe it. This is not always the case. For example, thousands of people used to believe that the sun revolved around the earth. Their belief proved to be false. 

Begging the Question:
"begs the question" is often misused to mean "raises the question," however, the intended meaning is to assume a conclusion in one’s question. A police officer once opened a conversation with me by asking, "How much have you had to drink tonight?" The question assumes the conclusion that I had been drinking, even though I hadn’t been. 

Confusing association with causation:
This is similar to the post-hoc fallacy in that it assumes cause and effect for two variables simply because they occur together. This fallacy is often used to give a statistical correlation a causal interpretation. For example, during the 1990’s both religious attendance and illegal drug use have been on the rise. It would be a fallacy to conclude that therefore, religious attendance causes illegal drug use. 

Confusing currently unexplained with unexplainable:
Because we do not currently have an adequate explanation for a phenomenon does not mean that it is forever unexplainable, or that it therefore defies the laws of nature or requires a paranormal explanation. For example, it seems remarkable that ancient people could have built massive structures like the pyramids without modern machines, but this does not mean they used magic or were helped by extraterrestrials. 

False Analogy:
Analogies are very useful as they allow us to draw lessons from the familiar and apply them to the unfamiliar. Life is like a box of chocolate – you never know what you’re going to get. A false analogy is an argument based upon an assumed similarity between two things, people, or situations when in fact the two things being compared are not similar in the manner invoked. An example culled from talk radio goes like this, "Liberals talk about race all the time, you know who else did that, the Nazis." 

False Continuum:
The idea that because there is no definitive demarcation line between two extremes, that the distinction between the extremes is not real or meaningful. For example, it is wrong to assume that because there is a fuzzy line between cults and religion, all religions must be cults.

False Dichotomy:
Arbitrarily reducing a set of many possibilities to only two. "You are either with me or against me" is a very common example. Couldn’t I support some of things you do and disapprove of others.

False Generalization
This fallacy states that just because one member of a group has a certain quality, the whole group has the same quality. This argument often pops up when a "foreign" person commits a crime. The whole population to which the foreigner belongs often takes the blame for the evil actions of one of its members.

Inconsistency (or the Double Standard):
Applying criteria or rules to one belief, claim, argument, or position but not to others. For example, some consumer advocates argue that we need stronger regulation of prescription drugs to ensure their safety and effectiveness, but at the same time argue that medicinal herbs should be sold with no regulation for either safety or effectiveness.


Non-Sequitur:
In Latin this term translates to "doesn’t follow". This refers to an argument in which the conclusion does not necessarily follow from the premises. In other words, a logical connection is implied where none exists. Such as "God is love. Love is blind. Ray Charles is blind; therefore, Ray Charles is God."

Post-hoc ergo propter hoc:
This fallacy follows the basic format of: A preceded B, therefore A caused B, and therefore assumes cause and effect for two events just because they are temporally related (the Latin translates to "after this, therefore because of this"). For example, "Have you seen my amazing lighting proof shoes? I bought them three months ago and I haven’t been struck by lightning ever since!"

Reductio ad absurdum (False):
In formal logic, the reductio ad absurdum is a legitimate argument. It follows the form that if the premises are assumed to be true it necessarily leads to an absurd (false) conclusion and therefore one or more premises must be false. For example a UFO enthusiast once argued that if I am skeptical about the existence of alien visitors, I must also be skeptical of the existence of the Great Wall of China, since I have not personally seen either. This is a false reductio ad absurdum because he is ignoring evidence other than personal eyewitness evidence, and also logical inference. In short, being skeptical of UFO’s does not require rejecting the existence of the Great Wall.

Slippery Slope:
This logical fallacy is the argument that a position is not consistent or tenable because accepting the position means that the extreme of the position must also be accepted. But moderate positions do not necessarily lead down the slippery slope to the extreme. This argument is often used against those who want to legalize marijuana because it is a "gateway" drug. It is also used by those against gay marriage, "If we let this happen, then people are going to start marrying their dogs!"

Straw Man:
A straw man argument attempts to counter a position by attacking a different position – usually one that is easier to counter. The arguer invents a caricature of his opponent’s position – a "straw man" – that is easily refuted, but not the position that his opponent actually holds. For example, someone who wanted to cut wasteful school spending might be targeted as someone who "just hates children." This is a "straw man" version of the position that schools should be run efficiently.

The Moving Goalpost:
A method of denial that involves arbitrarily moving the criteria for "proof" or acceptance out of range of whatever evidence currently exists. If new evidence comes to light meeting the prior criteria, the goalpost is pushed back further – keeping it out of range of the new evidence. Sometimes impossible criteria are set up at the start – moving the goalpost impossibly out of range – for the purpose of denying an undesirable conclusion.

Tu quoque:
Literally, "you too." This is an attempt to justify wrong action because someone else also does it. Children often employ this fallacy when talking about their siblings, or even their parents. If Bob’s sister Ruth steals a book, it’s still not okay for Bob to steal one too. If Bob’s parent uses a curse word, that does not mean that it’s okay for Bob to do it too.


Work Cited
"Logical Fallacies." The Skeptic's Guide to the Universe. SGU Productions LLC. 6 Feb. 2018. Web. 2018.　　http://www.theskepticsguide.org/resources/logical-fallacies.