Types Of Reasoning Flaws Flashcards
Errors in the Use of Evidence
-General Lack of Relevant Evidence for the Conclusion
The use of irrelevant data or information for a conclusion.
“The author cites irrelevant data.”
“Draws a conclusion not warranted by the evidence provided.”
“Uses inapplicable information to draw a conclusion.”
“Fails to give any reason for the judgment it reaches”
Ex: ‘Some critics claim that scientific progress has increased the polarization of the population. But these critics are wrong because even a cursory glance at the past shows that society is always somewhat polarized and some groups are inevitably alienated.’
Errors in the Use of Evidence
-Internal Contradiction
Occurs when the author makes conflicting statements
“Bases a conclusion on claims that are inconsistent with each other”
“Makes irreconcilable presuppositions”
“Introduces information that actually contradicts the conclusion”
“Claims presented in support of the conclusion conflict with the other evidence provided”
Ex: ‘Everyone should join our country club. After all, it’s an exclusive group that that links many of the influential members of the community.’
Errors in the Use of Evidence
-Exceptional Case/Overgeneralization
Takes a small number of instances and treats them like they support a broad or sweeping conclusion
“supports a general claim on the. basis of a single example”
“generalizes on the basis of what could be exceptional cases”
bases a broad claim on a few exceptional instances”
Ex: ‘Two of my friends were shortchanged at the store. Therefore, everyone gets shortchanged at that store.’
Error in the Use of Evidence
-Errors in Assessing the Force of Evidence
- Lack of evidence for a position is taken to mean that this position is false
“treats failure to prove a claim as constituting a denial of that claim”
“taking a lack of evidence for a claim as evidence undermining that claim”
Ex: ‘The White House has failed to offer any evidence that they have reached a trade agreement with China. Therefore, no such agreement has been reached.’
- Lack of evidence against a position is taken to mean that position is true
“treating the failure to prove a claim to be false as if it is a demonstration of the truth of that claim”
Ex: ‘There has been no evidence given against the existence of god, therefore god must exist.’
- Some evidence against a position is taken to mean that the position is false
“it confuses weakening an argument in support of a given conclusion with proving the conclusion itself to be false”
Ex: ‘Some historians claim that a lengthy drought preceded the fall of the Aztec empire. But we know from the Aztec writings that in at least one year during the supposed drought there was minor flooding. Thus, the claim that there was a lengthy drought prior to the fall of the Aztec empire is false.’
- Some evidence for a position is taken to prove that position is true
“the argument treats evidence showing the mere plausibility as if it proves the conclusion is in fact true”
Ex: ‘ We know that the defendant was in the vicinity of the area when the robbery occurred. Therefore, the defendant is guilty of the robbery.’
Source Argument
Can focus of the motives of or the actions of the source
Attacks the person behind or source of an argument, rather than the argument
“It is directed against the proponent of a claim rather than the claim itself”
‘Ex: The anti-smoking views expressed by Senator Smith should be ignored. After all, Smith herself is a smoker.’
Circular Reasoning
The author assumes as true what is supposed to be proven
“Argues circularly by assuming the conclusion is true in stating the premises”
“presupposes what it sets out to prove”
“assumes what it sets out to demonstrate”
Ex: ‘This essay is the best because it is better than all the others’
Errors of Conditional Reasoning
Either confuses a necessary condition for a sufficient condition or confuses a sufficient condition for a necessary condition
Mistaken Cause and Effect
Assuming a causal relationship on the basis of the sequence of events
Assuming a causal relationship hen only a correlation exists
Failure to consider an alternate cause for the effect, or an alternate cause for both the cause and effect
Failure to consider that the events may be reversed
Straw Man
When an opposing viewpoint distorts the initial argument in order to make it weaker
Appeal Fallacies
Appeal to authority – uses an authoritative viewpoint to convince an audience of the argument
Appeal to the popular opinion – uses the popular opinion to convince the audience of the argument
Appeal to emotion – attempts to make an appeal with emotion in place of reason
Survey Errors
A biased survey sample
Improperly constructed survey questions
Inaccurate responses to survey questions
Errors of Composition and Division
Author attributes a characteristic of part of the group to the group as a whole, or the inverse of this
Uncertain Use of a Term or Concept
The author uses a term or a concept to mean two or more different things, but portrays them as if they have the same meaning (i.e., value to mean money and value to mean ideology, but used interchangeably)
False Analogy
When an analogy is used for situations that are fundamentally different
False Dilemma
Falsely assumes only two courses of action are possible when there may be other courses
