Logical fallicies

Appeal to Authority

A fallacy in which a speaker or writer seeks to persuade not by giving evidence but by appealing to the respect people have for a famous person or institution. hey depend upon the substitution of a famous name for a serious argument. According to person 1, who is an expert on the issue of Y, Y is true. Therefore, Y is true.

Red Herring

A fallacy that introduces an irrelevant issue to divert attention from the subject under discussion describes a statement introducing an unrelated point instead of addressing the question under debate. red herring Loading students with hours of homework is pointless when the world is about to be destroyed by the greenhouse effect. (the assignment of homework is irrelevant to the emission of greenhouse gases)

False Analogy

A false or over-extended analogy is an assertion that because a similarity exists in one aspect, it must also exist in other aspects. false analogy X is like Y. Y has property P. Therefore, X has property P. (but X really is not too much like Y) Example #1: Not believing in the literal resurrection of Jesus because the Bible has errors and contradictions, is like denying that the Titanic sank because eye-witnesses did not agree if the ship broke in half before or after it san

ad hominem

An ad hominem argument evades the task of addressing the question and instead appeals to the feelings of the audience Clinton's infidelity to his wife invalidates his Mideast peace policy. (marital infidelity has no direct connection with international policy)

Circular Reasoning/Begging the Question

Begging the question, sometimes considered a synonym for circular reasoning, treats matters under debate as already established. explanation Clearly, Mary is failing the class because she cannot manage to achieve at the level required to pass. (a restatement of a point is not a proof of it)

Hasty Generalization

Hasty generalizations make poor arguments because they rely upon an non-exhaustive body of evidence. Generalizations may well be right most of the time, but they are also wrong some of the time. Moreover, they are usually not supported by specific information but by an appeal to common sense or common experience. explanation Mary's husband beats her; men always oppress women. (that this one case is true proves nothing about all men)

post hoc ergo propter hoc

Post hoc, ergo propter hoc, "after this, thus because of this," is an error created by assuming that sequence indicates causation. Many things happen in succession without any direct connection. Withdrawals have increased substantially since Professor Tod started teaching history at UNB; clearly he has driven students away. (there is no necessary connection between the higher dropout rates and Tod's teaching; they are related sequentially and the case for causation cannot be assumed)

non sequitur

This term means "it does not follow." A non sequitur is an illogical statement, one that seems to draw a conclusion not supported by the premises. ducation is the only way to combat unemployment. (many educated people are unemployed)

either/or fallacy

his is the fallacious presentation of two possibilities as the only possibilities. In many cases there are only two possibilities: Everyone must either consume nourishment or die; a battery terminal is either negative or positive.