For those that have studied debate, it can be frustrating to entertain arguments that contain fundamental logical errors.  Once understood, these fundamentals provide very tight structural frameworks for logical thought formulation. Debating those without this fundamental base, can be an exhausting excersize; however, the subtleties contained within the definitions of logical fallacy can be equally as frustrating to those without the base of knowledge to work from. At times, it appears that the other party is simply debating to hear themselves argue.  It often comes off as "logical snobbery".  

This Fan Post is simply meant to be a reference (I admit I dusted off some of the old college texts for accuracy and have various tidbits from that manuscript scattered throughout).  I won't pretend to know any more than the next guy that has studied the topic, but I figured it would be a good idea to create some material which all Field Gulls could access when formulating arguments. When applicable, I have attempted to tie these thoughts back into real world NFL examples for clarity. 

Some Basics

In short, a logical fallacy is an error of reasoning.  These errors are broken into two different groups (formal and informal fallacies).

A. Formal Fallacies (deductive) are your "air-tight" arguments.  With a well formed formal argument, it's impossible for the premises to be true and the conclusion to be false.  Any deductive argument that fails to meet these qualifications is fallacious.  Here is a classic, well-formed example with an NFL twist:

All Seahawks are NFL players.

Matt Hasselbeck is a Seahawk

Therefore... Matt Hasselbeck is an NFL Player.

B. Informal Fallacies (inductive) lend support to their conclusions, but don't establish with 100% certainty that their conclusions are true (even with 100% true premises).  The following would be a fallacy:

Every Superbowl Champion has had a positive regular season turnover ratio.

Therefore... next years Superbowl Champion will have a positive RS turnover ratio.

All inductive arguments deductively invalid. The premises of an inductive argument do not entail the truth of the argument's conclusion, and so even the most solid inductive arguments fall short of deductive validity.

Fallacy Classifications: There are 17 basic types of logical error broken into 3 classes.  There are many variations and sub classes of fallacious reasoning, but this should provide a good foundation.

CLASSIFICATION 1.

Logical Fallacies of Relevance:fail to provide adequate reason for believing the truth of their conclusions. 

A. Appeals to Force: Occurs when someone in a position of power threatens to bring down unfortunate consequences upon anyone who dares to disagree with a proposition.

"Either you agree with me on the Gus Bradley hiring or your banned from commenting on Field Gulls"

In this case, authority, or position of power, is never grounds for logical truth.

B. Appeals to Pity:  Is exactly the opposite of an appeal to force.  It o ccurs when a commenter points out negative consequences of not agreeing with their opinion.

"See?... this is why I never post on Field Gulls.  Nobody ever understands me. I will stop visiting this website."

C. Appeal to Emotion: Relies upon emotively charged language to arouse strong feelings that may lead an audience to accept its conclusion.

"Tim Ruskell is an antiquated relic, that rode the coat tails of a Tampa Bay Juggernaut that was already set in motion.  He is an opportunist and is ripping the sinews of the Seahawks soul apart."

The problem is that although the fiery language of the premise can create strong feelings in many members of its intended audience, even an overwhelming support of those feelings has nothing to do with the truth of the conclusion.    

D. Appeal to Authority: the opinion of someone famous or accomplished in another area of expertise is supposed to guarantee the truth of a conclusion.

Tim Ruskell believes that Colin Cole was worth the money and he's the GM of an NFL team.

You have never been in a Front Office of an NFL team, so I think Ruskell knows more then you.

This is a very common logical fallacy to fall into. Even in areas where someone may have special knowledge or skill we cannot accept the word of an individual as proof of anything. NFL execs are proven mistaken all the time. Their testimony is inductive evidence but never deductive proof of the truth of a conclusion. 

E. Ad Hominem (personal attacks): Is the exact opposite of appeal to authority.  This occurs when we are encouraged to reject a proposition because it is the stated opinion of someone regarded as disreputable in some way. 

Tim Ruskell believes Kelly Jennings was a good draft pick. 

Tim Ruskell was wrong about Brian Russell. 

Tim Ruskell was wrong about Colin Cole.

Therefore...Tim Ruskell is wrong about Kelly Jennings.

F. Appeal to Ignorance: proposes that we accept the truth of a proposition unless an opponent can prove otherwise.

Brian Brohm has never succeeded in the NFL

Therefore... Brian Brohm cannot succeed in the NFL.

Obviously the absence of evidence against a proposition is not enough to secure its truth. What we don't know could nevertheless be so.    This is exactly the argument John was correctly making in the Brohm thread, when he said..."You cannot prove what you don't know".

G. Irrelevant Conclusions: Can be very distracting as an argument.  This fallacy tries to establish the truth of a proposition by offering an argument that actually provides support for an entirely different conclusion.

The Seahawks don't have a good running game.

NFL teams need good offensive lines to have good running games.

Therefore, the Seahawks should draft offensive linemen in the next draft.

Here the premises might support some conclusion about NFL running-game success in general, but do not secure the truth of a conclusion distributed between all the factors that contribute to a good running game (OL, RB's, Blocking scheme).    

CLASSIFICATION 2.

Logical Fallacies of Ambiguity: are errors in reasoning that arise from the imprecise use of language. 

A. Equivocation: Stresses the use of an ambiguous word or phrase in one of its meanings in one of the propositions of an argument but also in another of its meanings in a second proposition.

Colin Cole is heavy.

What is heavy cannot be easily moved.

Therefore... Colin Cole cannot be easily moved.

If only it were this easy for our dear friend Mr. Cole.

B. Accent: is one of my favorites, and can be very subtle.  The fallacy of accent arises from an ambiguity produced by a shift of spoken or written emphasis. 

Matt Hasselbeck didn't throw many interceptions today.

Therefore... Matt Hasselbeck usually throws many interceptions.

Here the premise may be true if read without inflection, but if it is read with heavy stress on the last word seems to imply the truth of the conclusion.  Sneaky debaters can get away with murder on emphasis alone and always fall back on the validitiy of an un-stressed context.

C. Composition: involves an implication of some feature to every individual member of a class (or part of a greater whole) to the possession of the same feature by the entire class (or whole).   Basically this is an improper generalization.

The Seahawks offense is clicking on all cylinders and well organized.

Therefore... the Seahawks are well organized.

While the conclusion could very well be true, the problem is that the premise doesn't support it.  There could be a dozen reasons that the Seahawks ARE well organized, but those reasons aren't part of the arguments structure. You often see this fallacy appear when talking about Seahawks defense and a potential switch to a 3-4.  It usually goes something like this: "Most of the top defenses in the league are 3-4, therefore the Seahawks should find a way to switch to the 3-4."  Whether switching to the 3-4 would actually help the hawks is irrelevant.  The point is that using a general truth about a collective, and applying it as truth to a unit within the collective is fallacious.

D. Fallacy of Division: involves an inference from the attribution of some feature to an entire class (or whole) to the possession of the same feature by each of its individual members (or parts). Similar of course to the Fallacy of Composition except in reverse.

Feature Running Backs are in decline in the NFL.

Minnesota Vikings use a feature back system.

Therefore... the Minnesota Vikings are in decline. 

The important part of this fallacy of division is that even though something can be truly said in general of a whole group, it does not follow that the same can be truly said of any of its individual parts.    

CLASSIFICATION 3.

Logical Fallacies of Presumption: fail to provide adequate reason for believing the truth of their conclusions.

A. Fallacy of Accident: Tries to tie statements that are true as a general rule, into far more specific examples.

Quarterbacks are more important than Running Backs.

Mike Teel is a Quarterback

Adrian Peterson is a running back

Therefore, Mike Teel is more important than Adrian Peterson.

The truth of a general rule leaves plenty of room for exceptional cases, and applying it to any of them is a logical fallacy.

B. Converse Accident: Using a specific case that is unusual or atypical in some way, and then attempting to derive from this case, the truth of a general rule.

Matt Hasselbeck is bald and an excellent passer.

Therefore, bald quarterbacks are excellent passers.

It should be obvious that a single instance is not enough to establish the truth of such a general principle. 

C. False Cause: Infers the presence of a connection between two events simply because the events appear to occur in correlation.

The Seahawks wore thier throwback uniforms on Sunday.

They went on to win the game.

Therefore, the Seahawks won the game because of the throwback uniforms.

D. Begging the Question: Is using your conclusion within the premises for that very conclusion.  Sometimes known as circular logic as well.

"Since good draft picks must be strong steady leaders that produce on the field, it follows that Aaron Curry cannot be a good draft pick."

This argument is formally valid because it is impossible for their conclusions to be false if their premises are true. This is often a sticking point in an argument in that the conclusion cannot be false; HOWEVER , the real problem is that there is absolutely no support for their conclusion which has already been accepted without proof from the outset.

E. Complex Question

The fallacy of complex question presupposes the truth of its own conclusion by including it implicitly in the statement of the issue to be considered:

Do you expect the Seahawks to draft OL or DL?  Either way, your admitting they are going to blow the pick.

Final Word

The definitions contained within should be correct and I have attempted to double check all my analogies for accuracy as well.  Maybe if John has some time he can check and make sure I haven't overlooked something.

Hope this helps somebody.... sometime.