Common Flaw in Reasoning

“The author cites irrelevant data”

Errors in the Use of Evidence: General Lack of Relevant Evidence for Conclusion

“draws a conclusion that is not warranted by the evidence provided”

Errors in the Use of Evidence: General Lack of Relevant Evidence for Conclusion

It uses inapplicable information to draw a conclusion about the character of the character of the witness

Errors in the Use of Evidence: General Lack of Relevant Evidence for Conclusion

It fails to give any reason for the judgment it reaches

Errors in the Use of Evidence: General Lack of Relevant Evidence for Conclusion

bases a conclusion on claims that are inconsistent with teach other

Errors in the Use of Evidence: Internal Contradiction

the author makes irreconcilable presuppositions

Errors in the Use of Evidence: Internal Contradiction

introduces information that actually contradicts the conclusion

Errors in the Use of Evidence: Internal Contradiction

claims presented in support of the conclusion conflict with the other evidence provided

Errors in the Use of Evidence: Internal Contradiction

supports a general claim on the basis of a single example

Errors in the Use of Evidence: Exceptional Case/Overgeneralization

generalizes on the basis of what could be exceptional cases

Errors in the Use of Evidence: Exceptional Case/Overgeneralization

bases a broad claim on a few exceptional instances

Errors in the Use of Evidence: Hasty Generalization

treats failure to prove a claim as constituting denial of that claim

Errors in Assessing the Force of Evidence: Lack of evidence for a position is taken to prove that position is false

taking a lack of evidence for a claim as evidence undermining a claim

Errors in Assessing the Force of Evidence: Lack of evidence for a position is taken to prove that position is false

treating the failure to prove a claim to be false as if it is a demonstration of the truth of that claim

Errors in Assessing the Force of Evidence: Lack of evidence against position is taken to prove that position

it confuses weakening an argument in support of a given conclusion with proving the conclusion itself to be false

Errors in Assessing the Force of Evidence: Some evidence against a position is taken to prove that the positions is false

the argument treats evidence showing mere plausibility as if it proves that the conclusion is in fact true

Errors in Assessing the Force of Evidence: Some evidence for a position is taken to prove that position is true

it is directed against the proponent of a claim rather than against the claim itself

Source Argument

the attack is directed against the person making the argument rather than directing it against the argument itself

Source Argument

it draws conclusion about the validity of a position from evidence about the position’s source

Source Argument

assuming that legislation should not be supported based on the character of some supporters of the legislation

Source Argument

assuming that legislation should not be supported based on the character of some supporters of the legislation

Source Argument

argues circularly by assuming the conclusion is true in stating the premises

Circular Argument

presupposes what is sets of to prove

Circular Argument

it assumes what is attempting to demonstrate

Circular Argument

taking the absence of an occurrence as evidence that a necessary condition for that occurrence also did not take place

Mistaken Negation

mistakes being sufficient to achieve a particular outcome for being required to achieve it

Mistaken Reversal

from the assertion that something is necessary to given goal the argument concludes that that thing is sufficient for its achievement

Confuses a necessary condition for a sufficient condition

It acts as if something that is necessary for a good leader is something that is sufficient to create a good leader

Confuses a necessary condition for a sufficient condition

confuses an assured condition with a required condition

confuses a sufficient condition for a necessary condition

mistakes the occurrence of one even after another for proof that the second event is the result of the first

Assuming casual relationship on the basis of the sequence of events

mistakes a temporal relationship for a causal relationship

Assuming casual relationship on the basis of the sequence of events

confusing the coincidence of two events with a casual relation between the two

Assuming casual relationship when only a correlation exists

assumes a casual relationship where only a correlation has been indicated

Assuming casual relationship when only a correlation exists

fails to exclude an alternative explanation for the observed effect

fails to consider an alternative cause for the effect, or an alternate cause for both the cause and the effect

overlooks the possibility that the same thing may casually contribute to both

fails to consider an alternative cause for the effect, or an alternate cause for both the cause and the effect

the author mistakes an effect for a cause

failure to consider that the events may be reversed

refutes a distorted version of an opposing position

Straw Man

misdescribes the opposing position, thus making it easier to challenge

Straw Man

Portrays opponents’ views as more extreme than they really are

Straw Man

distorts the proposal advocated by opponents

Straw Man

the judgement of experts is applied to a matter in which their expertise is not relevant

Appeal to Authority Fallacy

the argument improperly appeals to the authority of the supervisor

Appeal to Authority Fallacy

bases a conclusion solely on the authority of the claimant without seeking further proof

Appeal to Authority Fallacy

popular sentiment is treated as definitive proof of a claim

Appeal to Popular Opinion/Appeal to Numbers Fallacy

the argument tries to undermine the claim by appealing to public opinion

Appeal to Popular Opinion/Appeal to Numbers Fallacy

a conclusion is judged to be false silly because most believe it to be false

Appeal to Popular Opinion/Appeal to Numbers Fallacy

the author makes an appeal to public opinion without requiring an adequate basis for the conclusion of the argument

Appeal to Popular Opinion/Appeal to Numbers Fallacy

attempts to persuade by making an emotional appeal

Appeal to Emotion Fallacy

the argument appeals to emotion rather than reason

Appeal to Emotion Fallacy

uses evidence drawn from a sample that may not be representative

Survey Errors: the survey uses a biased sample

bases a conclusion on survey responses that were gained through faulty questioning

Survey Errors: The survey questions are improperly constructed

generalizes from an unrepresentative sample

Survey Errors: the survey uses a biased sample

assumed that every polled individual provided a truthful response

Survey Error: Respondents to the survey give inaccurate responses

assuming that because something is true of each of the parts of a while it is true of the whole

Error of Composition (part to whole)

improperly infers that all union member have a certain attribute from the premise that most union members have that attribute

Error of Composition (part to whole)

takes the beliefs of one scientist to represent the belief of all scientists

Error of Composition (part to whole)

presumes without warrant that what is true of a whole must also be true of each of its parts

Error of Division (whole to part)

depending on the ambitious use of key term

Uncertain use of Term or Concept

it confuses two different meaning of the word “x”

Uncertain use of Term or Concept

the author’s conclusion depends on defining a key term in two different ways

Uncertain use of Term or Concept

equivocates with respect to a central concept

Uncertain use of Term or Concept

treats two very different cases as if they are similar

False Analogy

treats two things differ in critical respects as if they do not differ

False Analogy

fails to consider that some voters may be neither strong supporters nor strong opponents of the suggested amendment

False Dilemma

treats a claim about the current state of affairs as if it were a claim about what has been the case for an extended period

Time shift Errors

draws an unwarranted inference from what has been true in the past to what will be true in the future

Time Shift Errors

when information about a relative relationship is used to draw an absolute conclusion OR when a relative conclusion is drawn from absolute information

Relativity Flaw

the idea that the investments already made are basically costs that cannot be recovered without further effort

Sunk Cost/ Concord Fallacy

the argument confuses an increasing market share with an increase in overall revenue

Numbers and Percentages