More Bad Reasoning and Bad Rhetoric Violence to both People and Logic.

More Bad Reasoning and

Bad Rhetoric

Violence to both People and Logic

Ad Hominem FallaciesAbout persons instead of premises

Personal attack/favoritism


Personal attack/favoritism Inconsistency (incl. double standard)


Personal attack/favoritism Inconsistency (incl. double standard) Circumstantial (positive or negative)


Personal attack/favoritism Inconsistency (incl. double standard) Circumstantial (positive or negative) Poisoning the well


Personal attack/favoritism Inconsistency (incl. double standard) Circumstantial (positive or negative) Poisoning the wellCharacteristics of the person are not irrelevant when credibility of the source is an important factor in determining whether a claim will be expected.


Personal attack/favoritism Inconsistency (incl. double standard) Circumstantial (positive or negative) Poisoning the wellCharacteristics of the person are not irrelevant when credibility of the source is an important factor in determining whether a claim will be expected.

Genetic FallacyAbout origins of ideas instead of premises

Straw ManSubstituting a weak invention for reality

A strategy of refutation


A strategy of refutation Reworks some part of a case to make it

less viable



less viable Uses exaggeration or oversimplification

to distort original position



less viable Uses exaggeration or oversimplification

to distort original position The altered version of the original is

easier to refute than the original

False DilemmaTreating contraries as contradictories

Occurs when a decision must be made


Occurs when a decision must be made Limits alternatives (to two in a dilemma)


Occurs when a decision must be made Limits alternatives (to two in a dilemma) May use straw man technique to make one

alternative more attractive



alternative more attractive May show up as “either-or” or “if-then”



alternative more attractive May show up as “either-or” or “if-then” May show up as perfectionist fallacy (If

it’s not perfect, then it’s not acceptable.)



alternative more attractive May show up as “either-or” or “if-then” May show up as perfectionist fallacy (If

it’s not perfect, then it’s not acceptable.) May show up as line-drawing fallacy

(demand that category lines always be clear)

Slippery SlopeMisrepresenting probability and necessity

One version asserts in the manner of inductive argument that some action will inevitably (or almost certainly) lead to some improbable consequence

Slippery SlopeMisrepresenting probability and necessity

One version asserts in the manner of inductive argument that some action will inevitably (or almost certainly) lead to some improbable consequence

Second version asserts in the manner of a justification or statement of principle that once committed to a course of action, it must be followed to its conclusion

Misplacing Burden of ProofAppeal to Ignorance

An attempt to evade responsibility

Burden of proof: the requirement to supply support for a claim




Burden of proof shifts, depending on conditions (lower initial plausibility, affirmative more than negative, special circumstances such as judicial “innocent until proven guilty”)




Burden of proof shifts, depending on conditions (lower initial plausibility, affirmative more than negative, special circumstances such as judicial “innocent until proven guilty”)

Problem may occur unexpectedly in debate

Begging the QuestionSkipping over an important issue

May occur as a conclusion that restates a premise



May occur as a premise controversial on the same grounds as the conclusion



May occur as a premise controversial on the same grounds as the conclusion

May occur as a premise that presupposes the conclusion

Example: We need to widen this road because there aren’t enough lanes to handle the traffic. (Begs the question of whether all that traffic should or must be on that road. Does not beg the question of how many lanes are needed.)

More Bad Reasoning and Bad Rhetoric Violence to both People and Logic.

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