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->''"I live by syllogisms: God is love. Love is blind. Music/StevieWonder is blind. Therefore, Stevie Wonder is God. I don't know what I'd believe in if it wasn't for that."''
-->-- '''Creator/StephenColbert''', ''Series/TheColbertReport''

Also called the Politician's Syllogism or [[http://en.wikipedia.org/wiki/Equivocation Equivocation]].

A standard three-step syllogism uses three terms -- the things that are being linked by the line of reasoning. If A, then B. If B, then C. Therefore if A, then C. The fallacy of four terms occurs when, [[ExactlyWhatItSaysOnTheTin exactly like it says]], ''four'' terms are used instead of three. In most cases, a single term (B) is used two (or more) times, in differing contexts with different meanings; and yet the argument treats the two usages as exactly the same, since the same term was used.

It's best explained by this example from ''Film/LandOfTheBlind.''

->A dry crust of bread is better than nothing\\
But nothing is better than a big juicy steak.\\
Therefore, a dry crust of bread is better than a big juicy steak.

This uses two different meanings of the word "nothing." The first line uses "nothing" to mean "a lack of food", while the second line uses "nothing" as "no such thing exists."



* Comedian Creator/RichardJeni talks about when he learned about the syllogism in college in his ''Crazy from the Heat'' stand-up routine. God is love. Love is blind. Therefore, Music/RayCharles is God. Also, men are going bald, and they're from planet Earth. Women are not losing hair. Therefore, women are not from Earth.

* In the Creator/WoodyAllen film ''Film/LoveAndDeath'', Allen's character Boris gives this monologue: "What would Socrates say? All those Greeks were homosexuals. Boy, they must have had some wild parties. I bet they all took a house together in Crete for the summer. A: Socrates is a man. B: All men are mortal. C: All men are Socrates. That means all men are homosexuals."

* There's an old joke revolving around the word ''nothing'', where a bar patron turns down a beer from the bartender because "nothing is better than a cold drink".
** ComicStrip/{{Garfield}} has a similar philosophy. "If nobody is perfect, I must be nobody."
** Similarly, Anadin pain pills used to be marketed with the slogan "Nothing acts faster than Anadin", prompting the zinger "So take nothing -- it's cheaper".
** Related is "There is nothing like a good cup of coffee... and this is nothing like a good cup of coffee."
* An old joke: When you drink, you get drunk. When you get drunk, you go to sleep. When you go to sleep, you commit no sin. When you commit no sin, you go to {{Heaven}}. So, let's all get drunk and go to Heaven! Which is inverted in [=DirecTV's=] Advertising/GetRidOfCable commercials that begin with [[CableSatelliteMudslinging some frustration pertaining to cable]], and follows up with an increasingly bizarre set of DisasterDominoes.
* This joke: A kid asks his teacher "You wouldn't punish me for something I didn't do, would you?" The teacher says "Of course I wouldn't." The kid says, "Good, because I didn't do my homework!" (He's changing the meaning of "something I didn't do" from "something wrong that was not done by me" to "something I should have done and failed to.")
* A cat has three tails. No cat has two tails, and one cat has one more tail than no cat; therefore, one cat has three tails.
* Two versions of {{Fauxtivational Poster}}s in places of education:
** One version:
-->Knowledge is power.\\
Power corrupts.\\
Study hard. [[EvilIsCool It makes you evil]].
** Alternatively:
-->Knowledge is power.\\
Power corrupts.\\
Corruption is a crime.\\
Crime never pays.\\
Study hard. It makes you broke.
* Another commonly cited example:
-->All dogs have four legs.\\
My cat has four legs.\\
Therefore, my cat is a dog.

* In ''Literature/{{Discworld}}'', libraries warp spacetime because "knowledge=power=energy=matter=mass", and enough mass gives you a blackhole.

[[folder:Live-Action TV]]
* From ''Series/TheColbertReport'':
-->''"I live by syllogisms: God is love. Love is blind. Music/StevieWonder is blind. Therefore, Stevie Wonder is God. I don't know what I'd believe in if it wasn't for that."''
* An episode of ''Series/YesMinister'' called this by name, as "The Politician's Syllogism", specifically the form: "Something must be done. This is something. Therefore we must do this." The two different meanings of "something": "A solution to this problem" and "A thing" are mixed and said to be the same.

* This excerpt from Music/TheSmashingPumpkins' "Zero":
-->''Emptiness is loneliness.\\
And loneliness is cleanliness.\\
And cleanliness is godliness.\\
And God is empty, just like me.''

* ''Theatre/AnyoneCanWhistle'' explains in "simple" terms what's wrong with leftists:
-->The opposite of left is right,\\
The opposite of right is wrong,\\
So anyone who's Left is wrong -- right?
* [[ZerothLawOfTropeExamples Shakespeare did it first.]] In ''Theatre/AsYouLikeIt'', Touchstone proves that Corin is going to hell because he's never been in court.
-->'''Touchstone:''' Why, if thou never wast at court, thou never sawest good manners; if thou never sawest good manners, then thy manners must be wicked; and wickedness is sin, and sin is damnation. Thou art in a parlous state, shepherd.

[[folder:Web Comics]]
* In [[http://www.giantitp.com/comics/oots0725.html this]] ''[[Webcomic/TheOrderOfTheStick Order of the Stick]]'', the Empress is committing the Four Terms fallacy by using "grown larger" in two different senses: Dragons that are more powerful have grown larger (as a result of age), so she thinks that if she grows larger (by eating more and getting fat) that she will also be more powerful. That's not the only fallacy involved in her reasoning, either.

[[folder:Real Life]]
* In a museum, an employee sees a patron tapping on one of the replicas with his fist.
-->'''Employee:''' Sir, please don't touch that.\\
'''Patron:''' But it's a replica, isn't it?\\
'''Employee:''' Yes, it is, but we still ask for you not to touch it.\\
'''Patron:''' Well, it's not under a glass case, which means it's not valuable. I have every right to touch it.\\
'''Employer:''' No, actually--\\
'''Patron:''' Yes, if I see something that's not cased, it means I can touch it, AND I WILL TOUCH IT!
:: :The four terms used in the fallacy here are
## "It is not in a glass case"
## "I can (in the sense of "am physically able to") touch it",
## "I can (in the sense of "am permitted to") touch it" and
## "I will touch it".
:: :If 1 is true, then 2 is true; if 3 is true, then 4 is true. What's missing is the necessary step establishing either that 2 and 3 are the same (they aren't), or, that if 2 is true, 3 is true as well (it isn't).
* The most famous version is probably this:
-->''All the world loves a lover\\
I love you, therefore I am a lover\\
You are all the world to me, therefore you love me''
* Commonly used in LSAT testing for law school admissions in the United States. For example, using the word interest to mean financial stake, concern, or welfare. "The judge has no financial ties to the settlement with ABC Company. He is completely disinterested." This is not the same thing as saying he is "uninterested."
* Mathematics easily falls prey to this if you ignore a few key rules, e.g.:
x/0 is undefined\\
0/0 is simultaneously 1,0, and undefined\\
1 is equal to 0 and both are undefined.
* Also in mathematics:
-->Women = Time, Money\\
Since Time = Money,\\
Women = Money, Money\\
= Money squared\\
Since Money = the root of all Evil,\\
Women = (the square root of Evil) squared\\
Women = Evil
* Then there's the story about the parent who buys {{Hentai}} for their 10-year-old, only to return it in a rage to the store where they bought it, because in spite of the explicit picture on the front, and the ratings and warnings all over the box, reasoning that, [[AnimationAgeGhetto "It's a cartoon, and cartoons are for kids, so it must be kid-friendly!"]]