Fallacies of Ambiguity and Grammatical Analogy.

==Semantic Fallacies==
This category is up of problems concerning purposeful or accidental vagueness. They include: Vagueness, Equivocation/Semantic fallacy, Euphemisms, Amphiboly, Accent and the fallacies of analogy - Composition and Division.
===Vagueness===
Also known as weasel words. These types of fallacies occur when premises contain terms that are so fuzzy as to be practically meaningless. Example: Purchases of "Chi rings' are told that if you wear the ancient Asian power ring, it will increase your Chi, your life force, and lead to maximized health. Just what is Chi, or life force? What exactly is 'maximized health'? The answer to that question usually is "Anything even remotely positive that happens after wearing a Chi ring"
===Equivocation===
Also known as Conflation. The purposeful or erroneous transposition of meaning when the same word is used in two premises (or a premise and a conclusion), that is actually used in two different senses. This is also known as 'Weasel Words' - the use of which allow unscrupulous arguers to change their meaning after the fact. 'I didn't mean that, I meant this...'
A simple example: 'Banks have money. Rivers have banks. Therefore, whoever owns a river has a lot of money' Perhaps a person who could own a river would have a lot of money, but this point is not proven here. The error is apparent - it hinges on the claim that the word 'bank' has the same meaning in each premise. A more complex form, from an argument posed by the theist, J. P. Moreland from the book 'Does God Exist': 'Information must ultimately derive from an intelligent source. DNA possesses information - therefore, DNA shows design by an intelligent force- this force must be God'. Leaving aside the Kierkegaardian leap made from the premise to the conclusion, which commits the fallacy of missing the point (Why does it HAVE to be God? How about Allah? Zeus? Aliens from another dimension? The sole reason for choosing God seems to be that the arguer is a christian.) the error here is that the word 'information', when used in explaining the code in DNA, is used in a second sense - as a metaphor. The word 'blueprint' could have been used, yet no one would seriously suggest that there are real, miniature blueprints in DNA. If they did, perhaps then they could claim the existence of very tiny draftsmen. Equivocation happens purposely as well:
That all depends on what the meaning of 'is' is. - William Jefferson Clinton.
This fallacy is also known in classic Aristotelean logic as the fallacy of four terms.
Warning Catchphrase to look for: Examine analogies and metaphors carefully, especially when an analogy differs greatly from the phenomena discussed. (I.E. God is like a flower...) Ask for precising or operational definitions of words, even simple words, when they are used in argument form. Few words are univocal - with just one meaning.
===Euphemism===
This fallacy involves the use of a different word for a word we wish to avoid using, yet still containing the SAME meaning that we need to transmit. This is done to purposely obscure or confuse the reader to the true motives of the arguer, to make the reader or listener believe one desires to commit to one action when one really is favoring the opposite, or merely avoid making embarrassing admissions outright. In some cases the motivation is merely to aesthetically please - such as calling a toilet the 'necessarium' in front of the hoity-toity. The worst misuses of euphemisms may occur to people unaware that they are in fact using it - self delusion. 
Here is an infamous example of a euphemism being used to avoid making an embarrassing admission: One commits a crime by failing to comply with a law, so Dinkins is using a euphemism. This allows him to avoid the politically embarrassing situation of admitting in public that he is a law breaker, it not only fails, it also serves to show him as a cowardly liar.
It is no coincidence that I have chosen to use a politician as an example of euphemisms, for they are the worst offenders of this brand of fallacy - watch for how our government works. (I.e. - The Korean Conflict instead of War). For example, consider:
Republicans create new policies - Clinton Flip Flops.
Clinton was a pothead - George W. Bush had a 'substance abuse problem'.
Clinton has affairs - Henry Hide had a youthful indiscretion (in his 40s). 
Clinton raises taxes - Reagan 'enhanced government revenues'.
Lastly, consider the following three step transitions from good connotation to bad connotation, while all the words used have the same denotation. This method best explains the range of possible word choice when speaking about the very same phenomena:
I am firm; you are obstinate; he is a pigheaded fool.
I have reconsidered it; you have changed your mind; he is going back on his word.
I failed to comply with the law; you committed a crime; he is a felonious social deviant.
Warning Catchphrase to look for: The solution to uncovering this fallacy is simple in theory, but difficult in practice - as a logician you must ask the meaning of terms when you are unsure of them. If some military figure tells you that there will be a 'predawn vertical insertion' find out what the crap this means. (It means armed troops are going to parachute into some hostile country, and start killing poor bastards - but they don't want to tell you it that way...) Don't just pretend to be smart, ask and BE smart. If the military figure reveals that there has been some 'friendly collateral damage', be honest with yourself and say to him 'what the hell is friendly damage, buddy?!' You'll find out that it means that innocent bystanders were killed during a battle or a bombing mission. Again, the military guy ain't too pleased to tell you this. Asking someone what they mean takes on the risk of 'looking dumb' but remember, that is the very thought process being taken | advantage of in a euphemism! When Reagan looked America in the eye and spoke of revenue enhancements, he knew the average Republican voter had no idea what he meant, and that none of them would risk admitting ignorance to find out. That's how people trick you - by using your own hang-ups against you! Note: The opposite of Euphemism is 'dysphemism', which is the act of replacing a favorable term with a nasty, unfavorable term.
===Fallacy of Composition===
The fallacy of composition occurs when we erroneously transpose of a characteristic of a part of a system, or a person, to be characteristic of the whole, or the whole personality. It's similar to the fallacy of small sample bias/hasty generalization. Example: Oxygen and Hydrogen are both gases, it follows that H2O is also a gas' Another example: Al Gore agrees with the Unibomber on several environmental issues. It follows that Gore is just as reckless, uncaring and irresponsible as the Unibomber. The philosophical argument known as the 'Tragedy of the Commons' is an argument that relies on the composition fallacy. This is a philosophical argument that points out that what is good for individuals in society might have terrible ramifications for all members of said society if all members were to follow the same behavior - i..e one polluter benefits, many polluters suffer.
===Fallacy of Division===
The reverse of the composition fallacy - when a characteristic of the whole is erroneously transferred to one or more of its parts. Example: Water is a liquid, it follows that oxygen and hydrogen must also be liquids' A special case of the fallacy of division is the the clustering illusion or the Texas-sharpshooter fallacy. The Texas sharpshooter fallacy is the name epidemiologists give to the clustering illusion - the clustering illusion is the intuition that random events which occur in clusters are not really random events, i.e, finding a statistically unusual number of cancers in a given neighborhood--such as six or seven times greater than the average.
When this rate is re-connected to the overall population, we see that such a high localized rate is not all rare or even unexpected. Much depends on where you draw the boundaries of the neighborhood. The illusion is due to selective attention based on a false assumption: that a given rate for a phenomenon will be perfectly uniform across all members of that group. The term refers to the story of the Texas sharpshooter who shoots holes in the side of a barn and then draws a bull's-eye around the bullet holes: as long as the sharpshooter gets to pick where the target is afterwards, he will always remain a sharp shooter!
===Amphiboly===
When an argument depends upon a statement (Not just a word or phrase) that is ambiguous due to a grammatical error. This can occur from poor punctuation or a dangling participle.
===Accent===
Accent is a form of fallacy through shifting meaning. In this case, the meaning is changed by altering which parts of a statement are emphasized. For example: 'We should NOT SPEAK ILL of our friends' and 'We should not speak ill of our FRIENDS' Be particularly wary of this fallacy on the internet, where it's easy to misread the emphasis of what's written.
Category:Logic
Category:Informal Fallacies