robles - fallacy from ignorance, false dichotomy, false dilemma and bifurcation

8/12/2019 Robles - Fallacy From Ignorance, False Dichotomy, False Dilemma and Bifurcation

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ROBLES, WINDY M.LEGAL TECHNIQUE AND LOGIC

1. FALLACY FROM IGNORANCE is a logical fallacy of irrelevance occurring when

one claims that something is true only because it hasn't been proved false, or thatsomething is false only because it has not been proved true.

This fallacy is under the FALLACIES OF DEFECTIVE INDUCTION where inpremises may be relevant to the conclusion, but they are far too weak to support theconclusion and wholly inadequate; what are asserted as premises simply do notserve as good reasons to reach the conclusion drawn.

Argument of this form assumes that once something has not been proven false, it istherefore true. Conversely, such an argument may assume that since something has

not been proven true, it is therefore false. (This is a special case of a false dilemma,since assumes that all propositions must either be known to be true or known befalse)

In the appeal to ignorance, the arguer basically says, "Look, there's no conclusiveevidence on the issue at hand. Therefore, you should accept my conclusion on thisissue."

EXAMPLE:

"People have been trying for years to prove that God does not exist. But noone has yet been able to prove it. Therefore, God exists."

– In each case, the arguer tries to use the lack of evidence as support fora positive claim about the truth of a conclusion. There is one situationin which doing this is not fallacious: If qualified researchers have usedwell-thought-out methods to search for something for a long time, theyhaven't found it, and it's the kind of thing people ought to be able tofind, then the fact that they haven't found it constitutes some evidencethat it doesn't exist.

Fred said that he is smarter than Jill, but he didn’t prove it, so it must be false.

2. The fallacy of FALSE DICHOTOMY is committed when the arguer claims that hisconclusion is one of only two options, when in fact there are other possibilities. Thearguer then goes on to sho w that the 'only other opt ion ' i s c lear ly outrageous ,and so his preferred conc lus ion m ust be embraced ( leading the people to apar t icular ch oice).

A false dichotomy is typically used in an argument to force your opponent into anextreme position -- by making the assumption that there are only two positions.

EXAMPLES:



Either you let me go to the Family Values Tour, or I'll be miserable for the restof my life. I know you don't want me to be miserable for the rest of my life, soyou should let me go to the concert.

Either you use Speed Stick deodorant, or you will stink to high heaven. You

don't want to stink, so you better by Speed Stick.

Either I keep smoking, or I'll get fat. I don't want to get fat, so I better keepsmoking.

3. FALSE DILEMMA (Black & White Thinking) is committed when a person uses thefollowing pattern of "reasoning":

1. Either claim X is true or claim Y is true (when X and Y could both be false).2. Claim Y is false.

3. Therefore claim X is true.This occurs when an argument offers a false range of choices and requires that youpick one of them. The range is false because there may be other, unstated choiceswhich would only serve to undermine the original argument. I f you co ncede to p ickone of the ch oices , you accept the premise that those choic es are indeed theon ly ones po ss ib le. Usually, only two choices are presented thus the term “FalseDilemma”, however (Trilemma) or more choices offered.

Usually characterized by “either that or this” language, but can also be characterizedby omissions of choices.

EXAMPLES:

This line of "reasoning" is fallacious because if both claims could be false,then it cannot be inferred that one is true because the other is false. That thisis the case is made clear by the following example:

1. Either 1+1=4 or 1+1=12.2. It is not the case that 1+1=4.3. Therefore 1+1=12.

In cases in which the two options are, in fact, the only two options, this line ofreasoning is not fallacious. For example:

1. Bill is dead or he is alive.2. Bill is not dead.3. Therefore Bill is alive.

4. BIFURCATION is committed by the arguer when he or she claims that there areonly two mutually exclusive possibilities —when, in fact, there is a third option. Forthis reason the fallacy is also known as the either-or fallacy and the false dilemma .

Something is e i ther a member of one or the other but not both o r som e thi rdcategory.



EXAMPLES:

Either the traffic light is red, or it is green.

The traffic light is not green.

Therefore the traffic light is red.

This commits the fallacy of bifurcation, since there is a third possibility: since the lightcould be yellow.

robles - fallacy from ignorance, false dichotomy, false dilemma and bifurcation

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