Too many people nowadays are far too credulous, believing those who shower their words with assertions, failing to construct a single argument, valid or otherwise. The average person just does not know what exactly constitutes a valid argument. In the Socratic era, the only people who argued were philosophers who knew what they were doing; today, however, the privilege of arguing has been stolen by the most mediocrity of a superficial society. However, before anyone gets anywhere close to swaying me, they must first be at least briefly learned in logic. Following is a document on constructing logical arguments, along with a list of fallacies.

Introduction:

Logic is by no means universal law, for such science offers only current consistencies of observation; however, it can be a handy tool when used properly. There are many different kinds of logic and different kinds of arguments, but this document will just cover simple Boolean logic and the deductive argument. Logic will aid in the analysis of arguments, which will determine the validity of them. Such knowledge is especially significant when dealing with people who use fallacies or who try to argue when they do not know how.

The Deductive Argument:

Being commonly viewed as clear cut and persuasive, deductive arguments are always either valid or invalid because the offer proof of their conclusion. Deductive arguments consist of three stages: premises, inference, and conclusion, which will be described in detail later, but first I must make note of propositions, which are the building blocks of a deductive argument. This is a statement that is either true or false; it’s the meaning if the statement, basically.

Premises:

Premises are the core assumptions that an argument is built upon. In other words, the given reasons the argument should be accepted. These premises should be stated in an obvious manner, as anything to the contrary may be viewed as suspicious. It would also be wise to get your opponent to agree on the premises of an argument before proceeding further, as you will find that if your opponent views your premises as utter nonsense, odds are that they will respond much the same way towards the inference supporting your distrustful core assumptions. (Note that in internet debate, this is not always possible). On the same note, be careful not to overstate, as this will result in your opponent becoming vigilant in regards to everything following the overstatement. In other words, your opponent will find everything else you have to say less credible.

Inference:

Following the agreed premises, the argument proceeds into inference. This is where one or more propositions, which have already been accepted, are used to arrive at a new proposition. These can be implications made from the propositions, but you are limited to inferring from previous premises of the argument. Inference should help shape the argument in such a way as to lead towards the desired conclusion.

Conclusion:

If you have conducted the first two steps properly, you should arrive at the desired proposition, which is the conclusion of the argument. The basis of the premises, and the inference built from them, determines, in part, whether the argument is affirmed. There are a few situations which must be accounted for when dealing with the validity of an argument. You can build an argument from:

A.) true premises, arriving at a true conclusion

B.) false premises, arriving at a false conclusion

C.) false premises, valid inference, arriving at a true conclusion

The only thing that will result in an invalid argument is by starting from true premises, followed by valid inference, then miraculously arriving at a false conclusion. An argument is only considered to be sound, though, if it is valid and started from true premises and arrived at a true conclusion (as described in A).

Other Debate Formats:

Other debate forms utilize the above outline, but are focused more on a given resolution. The resolution is an assertion proposed by the host of the debate event, and the debaters then argue the affirmative or the negative to the position posed by the resolution. These other debate forms include the Lincoln Douglas Debate, which focuses on the value of the resolution; Policy Debate, which focuses on forming a plan to resolve the problem(s) presented by the resolution; and Public Forum Debate, which focuses not on a set of burdens, but on supporting the direct issues presented in the resolution. Another form of debate, one that is used more in the setting of formal meetings and pertains to a similar focus as the Policy Debate, is Parliamentary procedure, which is used by many organizations and by government to make decisions on pressing issues.

Some Notes on Debate:

Note that anything that does not follow the above outline is not an argument, but a statement or explanation, or assertion, which will not hold up in debate. Note also that any statement in the form A=>B can be rephrased as B=>A which may reveal the true absurdity of it. Also, do not allow your opponents awareness dwell to your emotions. Debate should not turn into a sermon; keep your respective emotions to yourself and seek more towards drawing peoples’ attention to the substance and meaning of the argument itself, and away from your anger or excitement. Another thing to keep in mind is clarity. Some logical fallacies concerning grammar are Accent, which is the act of shifting meaning, as in varying the parts of a statement that receive emphasis; and Amphiboly, which is where slipshod or ungrammatical phrasing causes a premise to sound vague.

Fallacies:

In logic, the term fallacy denotes a technical error which causes an argument to be invalid. There are a plethora of fallacies out there, and bellow is a brief list of some of the more common ones:

Ad hoc – gives an after-the-fact rationalization regarding an event that does not apply to other similar scenarios.

Affirmation of the Consequent – “A=>B, B is true, therefore A is true.” (See Conclusion).

The Appeal to common practice – A is a commonly performed action, therefore A is acceptable.

Appeal to emotion – pleasant emotions are associated with A, therefore A must be true.

Appeal to consequences of a belief – If A was not true, there would be negative consequences, therefore A is true (or there would be positive consequences if A is true.) This fallacy also applies to the contrary.

Anecdotal evidence – this is the fallacy of relying on anecdotal evidence as a primary source. (Anecdotal evidence is an unproved source such as urban legends, tabloids, the Bible, etc.)

Argumentum ad antiquitatem/Appeal to tradition – to assert that a thing is right or good simply because it is old.

Argumentum ad baculum/Appeal to force – when one resorts to force or the threat of force in order to coerce people to accept a conclusion. Note that the threat doesn’t have to come directly from the person making the claim.

Argumentum ad crumenam – to assert that money is principle to correctness, that those without money are sure to be more right.

Argumentum ad hominem – this term literally means “argument directed at the man.” There are two kinds: the abusive form, which is committed when one refuses to accept a statement and justifies said refusal by criticizing the person making the statement; and the circumstantial form, which is committed when one attempts to persuade another by referring to their particular circumstances, or when one denounces the person of procuring a conclusion from selfishness. It is not always fallacious to refer to one’s circumstances; for instance, one who is known to be a liar will be found less credible as a witness, however it will not prove their testimony false.

Argumentum ad ignorantiam – or “argument from ignorance.” The idea is that something must be true simply because it has not been proved otherwise, or vise versa. In scientific investigation, if due evidence for a given even has not been found, it can be inferred that said event did not occur, however this does not prove it with certainty. Argumentum ad ignorantiam is not the same as assuming something is false until otherwise proven.

Argumentum ad lazarum – to assert that one who is poor is sounder than one who is wealthy.

Argumentum ad logicam – the “fallacy fallacy”; to argue that a given proposition is false because it was presented as the conclusion of a fallacious argument. (See Conclusion).

Argumentum ad misericordiam/Appeal to pity/Special pleading – to appeal to pity in order to get a conclusion accepted.

Argumentum ad nauseam – the idea that an assertion is more likely to be accepted the more often it is heard. In truth, this just annoys people.

Argumentum ad novitatem – to assert that something is better simply because its new.

Argumentum ad numerum/Appeal to convention – the idea that the more people supporting a belief, the more credible it is.

Argumentum ad populum/Appealing to the gallery/Appealing to the people – to try to obtain acceptance of an assertion via appealing to a large group of people.

Argumentum ad verecundiam/Appeal to authority – to assert that a well-known person agrees with a position, to try to win support for said assertion. This sort of thing is not fallacious when used in an inductive argument, however, as it is relevant to refer to a widely-regarded figure in a particular field, so long as you are discussing that specific subject.

Audiatur et altera pars – this is more of a principle than a fallacy, but it is the principle that all premises of an argument should be stated explicitly.

The great Beethoven fallacy – this is used by pro-life advocates to argue that the baby that a woman aborts could turn out to be someone great like Beethoven. A similar fallacy is sometimes committed by pro-choice advocates to suggest that the baby a woman does not abort could turn into someone horrible like Hitler.

Bifurcation/the “black and white” fallacy/False dichotomy – to only present two alternatives for a given event when actually, others exist or can exist.

Circulus in demonstrando/Circular reasoning – to construct an argument so that you assume as a premise the conclusion that you are aiming for. In other words, the premise and conclusion are entirely the same, just reworded; the argument just runs in a circle.

Complex question/Fallacy of interrogation/Fallacy of presupposition/(interrogative form of) Begging the question – one form is the classic loaded question: to assume the answer to another question which has not even been asked. Another form is to demand an explanation for an untrue or currently unestablished thing.

Fallacies of composition – to assert that a common property belonging to an amount of individual items is the same when you put them all together. A similar fallacy, the “Just” fallacy or the fallacy of mediocrity, is to assume that any member of a set must have the same limitations as all other members of the set.

Converse accident/Hasty generalization – to create a general code from inspection of a small number of specific cases.

Converting a conditional/False biconditional – “If A then B, therefore if B then A.” This is not an argument, but a conditional statement.

Cum hoc ergo propter hoc – the idea that just because two events take place at the same relative time, they must be related by cause and effect, even though other factors may have played a role.

Denial of the antecedent – “A=>B, A is false, therefore B is false.” (See conclusion). Here, the fact that A is false doesn’t conclude anything regarding B.

The fallacy of accident/Sweeping generalization/Dicto simpliciter/Argument from stereotype – to apply a general rule to a specific scenario.

Fallacy of division – to assume that a specific property belonging to a given thing also applies to its individual parts.

Equivocation/Fallacy of four terms – to use a key word with its various different meanings in the same argument.

The extended analogy – in a debate over a general rule, when one assumes that by referring to two different situations, they connote that they are related.

The Gambler’s fallacy – the idea that because an event has occurred so many times in a row, it must break that consistency soon.

Ignoratio elenchi/Irrelevant conclusion – to assert that an argument supports a conclusion even though they have nothing to do with each other.

Misleading vividness – this is committed when a minute number of dramatic cases are held over high statistical evidence. That because a few neat cases occurred, similar cases are likely to occur, even though statistical evidence points to the contrary. (Remember, averages must always be taken into account)

The natural law fallacy/Appeal to nature – one form is to analogize a conclusion and some characteristic of the natural world, then assert that the conclusion is inevitable due to the natural world’s similarity. Another form is to assert that due to our association with the natural world we are inclined to imitate such behaviors as are seen in the natural world, and that anything to the contrary is “unnatural”.

The “No true Scotsman…” fallacy – “Suppose I assert that no Scotsman puts sugar on his porridge. You counter this by pointing out that your friend Angus likes sugar with his porridge. I then say, ‘ah, but no true Scotsman puts sugar on his porridge.” – Internet Infidels. This uses ad hoc combined with an attempt to shift the meaning of the original assertion.

Non causa pro causa – to claim that something is the cause of a given event, even though it has not in any way been shown to be such.

Non sequitur – to draw a conclusion from premises that have nothing to do with it.

Petito principii/Begging the question – to construct an argument in such a way that the premises assume the result that they are trying to prove.

Plurium interrogationum/Many questions – to demand a simple answer to a complex question.

Post hoc ergo propter hoc – an event happened before, therefore it caused an event to happen after-the-fact.

Red herring – to divert peoples’ attention away from the matter at hand by introducing irrelevant material.

Reification/Hypostation – to treat an abstract concept as a concrete thing.

Shifting the burden of proof – to put the burden of proof on the person questioning a claim; the burden of proof is always on the person making the assertion.

The Slippery slope argument – to assert that if one event is allowed, it will cause another, which will cause another, even though no such proof is given.

Straw man – to misrepresent one’s position in such a way that it can be attacked more easily, without addressing the actual arguments made.

Tu quoque – to make a personal attack on your opponent by asserting that because they performed a certain act, it must be okay for you to perform it as well.

Fallacy of the undistributed middle/“A is based on B” fallacies/”… is a type of” fallacies/Fallacy of the excluded middle – to assert that things are similar, without stating how they are similar.

Works Consulted:

http://www.infidels.org/library/modern/mathew/logic.html

The Elements of Style, Third Edition, by William Shrunk Jr. and E.B. White

The God Delusion, by Richard Dawkins

http://www.nizkor.org/features/fallacies/