Commonplace Book – Pages: 137-138
Texas Sharpshooter Fallacy: This fallacy occurs when someone jumps to the conclusion that a cluster in some data must be the result of a cause. However, the cluster may well be the result of chance, in which it was not caused by anything. Even if the cluster is not the result of chance, there may be are other possible reasons for the clustering.
Tu Quoque: When one attempts to defend oneself or another from criticism by turning the critique back against the accuser. Whether the accuser is guilty of the same, or a similar wrong is irrelevant to the truth of the original charge.
Two Wrongs Make a Right: Involves the attempt to justify a wrong action by pointing to another wrong action. Often, the other wrong action is of the same type or committed by the accuser, in which case it is the subfallacy of Tu Quoque.
Undistributed Middle Term: Any form of categorical syllogism in which the middle term is not distributed at least once. In a valid categorical syllogism, the middle term is distributed in at least once of its occurrences.
Vagueness: Occurs only when the appearance of soundness in an argument depends upon vagueness in its terms. It is sometimes a boobytrap which can cause the person to fall into fallacious reasoning.
Wishful Thinking: An argument whose premise expresses a desire for the conclusion to be true.
Commonplace Book – 136-137
Redefinition: It is not necessarily fallacious to give a term a new meaning, but it is a logical boobytrap. There is always a danger of slipping back into using the term in its old meaning out of habit, which could cause a fallacy of equivocation.
Regression Fallacy: The result of a statistical phenomenon known as ‘regression to the mean.’ That is, the tendency of a variable characteristic in a population to move away from the extreme values towards the mean.
Scope Fallacy: A technical notion. Such as, ‘all that glitters is not gold.’ In a narrow scope, the ‘not’ can mean ‘all that glitters is non-gold.’ In a broad scope, the ‘not’ can mean ‘all that glitters is not always gold.’
Some Are / Some Are Not: The mistake of confusing logical implication and conversational implicature by thinking that ‘some are’ statements logically imply ‘some are not’ statements, when the former statements only conversationally implicate the latter.
Special Pleading: Occurs when someone argues that a case is an exception to a rule based upon an irrelevant characteristic that does not define an exception. People often apply a ‘double standard’, which makes an exception to the rule for themselves – or people like them – but applies it to others.
Straw Man Fallacy: When the arguer is attempting to refute his opponent’s position by attacking a position not held by his opponent.
Syllogistic Fallacy: Any non-validating form of categorical syllogism.
Commonplace Book – Pages 130-131
Loaded Words: It is not inherently fallacious, however it is often a logical boobytrap, which may cause an unwarranted evaluation. The fallacy is committed either when an arguer attempts to use loaded words in place of an argument, or when an arguer makes an evaluation based on the colorful language, rather than on the merits of the argument itself.
Fallacy of Modal Logic: Modal logic studies logical relations involving modalities, which are ways in which propositions can be true or false. Modal fallacies are formal fallacies in which modality plays a role in the fallaciousness of a type of argument.
Modal Scope Fallacy: Modalities, like other logical concepts such as negation, have scope, that is, they logically influence a part of any sentence in which they occur. The modal scope occurs when this ampiboly is exploited.
Poisoning the Well: To poison the well is to commit a pre-emptive strike against an opponent. It can be abusive or circumstantial. It is a logical boobytrap set by the poisoner to tempt the audience into committing an ad hominem fallacy.
Probabilistic Fallacy: One which concludes that something has some probability based upon information about probabilities given in its premise. Such an argument is invalid when the inference from the premise to the conclusion violates the laws of probability. Probabilistic fallacies are formal ones because they involve reasoning which violates the formal rules of probability theory.
Propositional Logic: A system which deals with the logical relations that hold between propositions taken as a whole, and those compound propositions which are constructed from simpler one with truth – functional connectives. Since a validating argument form is one in which it is impossible for the premise to be true and the conclusion false, then the fallacy is one with a true premise and a false conclusion.
Quantificational Logic Fallacy: An extension of propositional logic which examines the logical properties of some of the internal grammatical structure of simple, non-compound propositions. To show that a quantificational argument is non-validating, it suffices to find an instance of that form with true premise and a false conclusion.
Question-Begging Analogy: An analogical argument begs the question when the strength of the analogy depends upon some controversial point at issue.
Commonplace Book – 129-130
Genetic Fallacy: It is the most general fallacy of irrelevancy involving the origins or history of an idea. It’s fallacious to either endorse or condemn an idea based on its past – rather than on its present – merits or demerits, unless it’s past in some way effects its present value.
The Hitler Card: ‘Argumentum ad Nazium‘ Playing the Hitler Card demonizes opponents in debate by associating them with evil, and almost always derails the discussion. Also when people become convinced by guilt by association arguments that their political opponents are not just mistaken, but are as evil as Nazis, reasoned debate can give way to violence.
The Hot Hand Fallacy: Whenever a gambler thinks he is ‘hot’ or ‘cold’ he will increase or decrease his wagers, but fail to appreciate statistical independence. So, a gambler’s odds of winning/losing a current bet is not affected by whether the gambler has won/lost previous bets.
Irrelevant Thesis: ‘Ignoratio Elenchi‘ One argument which distracts the audience from the issue in question through the introduction of some irrelevancy. This frequently occurs during debates when there is an implicit topic, yet its easy to lose track of it. By extension, it applies to any argument in which the premises are logically irrelevant to the conclusion.
Illicit Major: Any form of categorical syllogism in which the major term is distributed in the conclusion, but not in the major premise.
Illicit Minor: Any form of categorical syllogism in which the minor term is distributed in the conclusion but not in the minor premise.
Illicit Negative / Affirmative: Any form of categorical syllogism with a negative conclusion and affirmative premises. It violates the rule that any validating form of categorical syllogism with both premises affirmative has an affirmative conclusion.
Illicit Process: Any form of categorical syllogism in which a term is distributed in the conclusion and in undistributed in the premise. It violates the rule that in a validating form of categorical syllogism, in which the term must be distributed in both.
Illicit Quantifier Shift: Refers to the two quantifiers at the beginning of the premise and conclusion of arguments of this form, like “every” and “some.” “Shift” refers to the fact that the fact of the difference between the premise and conclusion of this form of argument consists in a shift in the order of the quantifiers.
Illicit Substitution of Identicals: ‘Masked Man Fallacy’ A validating form of argument so long as the context in which it occurs is extensional, or referentially transparent. Basically, one is misled into thinking that substitution is valid in all contexts.
Improper Transportation: Occurs when the antecedent and consequent of the conclusion of a transposition the antecedent and consequent of the conditional premise are switched and negated. In an improper transposition, the antecedent and consequent are negated, but not switched.
Commonplace Book – Pages 128-129
Fake Precision: This fallacy occurs when an argument treats information as more precise than it really is. This happens when imprecise information contained in the premises must be taken as precise in order to adequately support the conclusion. One common effect of overly-precise numbers is that they impress some people as scientific.
False Analogy: Some arguments from analogy are based on analogies that are so weak that the argument is too weak for the purpose to which it is put. Therefore, while the strength of an argument from analogy depends upon the strength of the analogy in its premises, it is not solely determined by that strength.
False Cause: ‘Non Causa Pro Causa‘. A causal argument must violate the canons of good reasoning about causation in some common or deceptive way. Mistakes about event-level causation are the result of confusing coincidence with causation.
False Conversion: Conversion is a validating form of immediate inference for E- and I- type categorical propositions. To convert such a proposition is to switch the subject and predicate terms of the proposition, which is non-validating for the A- and O- type propositions. Hence, the fallacy is converting A- or O- type proposition.
Formal Fallacy: A formal fallacy is a type of argument, the logical form of which is non-validating, and which is either deceptive and likely to be committed, usually by having a logical form that’s similar to a validating form of argument, or part of system of rules such that any argument of a type which the rules can be applied to, and which commits no fallacy, thereby breaks no rules.
Four Term Fallacy: A two premise argument containing four terms which results from a validating syllogistic form by substituting two distinct terms for one variable. It violates the syllogistic rule that all valid categorical syllogisms have exactly three terms.
Fallacy Fallacy: ‘Argumentum ad Logicam‘ – Like anything else, the concept of logical fallacy can be misunderstood and misused, and can even become a source of fallacious reasoning. The fallacy is committed when you jump to the conclusion that just because one argument for it is fallacious, no argument for it can exist.
Commonplace Book – Pages 100, 105-106, 128
Denial of the Antecedent: Together with ‘Affirming the Consequent’, this is a fallacy which involves either confusion about the direction of a conditional relation, or a confusing of a conditional with a biconditional proposition. Specifically, it occurs when a premise of an argument denies the truth of the antecedent of a conditional premise, then concludes by denying the truth of the conditional premise’ consequent. For example, if P then Q. Not P. Therefore, not Q.
Denying a Conjunct: Negating a conjunction – ‘not both’, which is sometimes abbreviated as ‘nand’ – means that at least one of the conjuncts is false, but it leaves open the possibility that both conjuncts are false. So, if we know that one of the conjuncts are true, we may validly infer that the other is false. In contrast, if we know that one of the conjuncts is false, we cannot validly infer from that information alone that the other is true, since it may be false as well.
Division: See ‘Composition.’ Some properties are such that, if a whole object has the property, then all of its parts will too – for example, invisibility. However, not all properties are like this – for instance, visibility. If P is a dissective property, then the argument form above is validating, but definition of what such a property is. However, if P is not dissective, then the argument form is non-validating, and y any argument of that form commits the fallacy of division.
Doctrine of Maturity of Chances: ‘A fair gambling device has produced a run. Therefore, on the next trial of the device, it is less likely than chance to continue the run.’ Problem is, two events are statistically independent when the occurrence of one has no statistical effect upon the occurrence of the other. Any gambler who thinks that he can record the results of a roulette wheel, or the throws at a craps table and use this information to predict future outcomes is committing some form of gambler’s fallacy.
Doublespeak: ‘Equivocation’ is the type of ambiguity which occurs when a single word or phrase is ambiguous, and this ambiguity is not grammatical but lexical. So, when a phrase equivocates, it is not due to grammar, but to the phrase as a whole having two distinct meanings. Of course, most words are ambiguous, but context usually makes a univocal meaning clear. Also, equivocation alone is not fallacious, though it is a linguistic boobytrap which can trip people into committing a fallacy.
Exclusive Premises: Any form of categorical syllogism with two negative premises. It violates the fact that at least one premise of a valid categorical syllogism must be affirmative.
Existential Fallacy: Any argument whose conclusion implies that a class has at least one member, but whose premises do not so imply. A proposition has existential import if it implies that some class isn’t empty, that is, that there is at least one member of the class.
Emotional Appeal: An appeal to emotion is a type of argument which attempts to arouse the emotions of its audience in order to gain acceptance of its conclusion. Appeals to emotion are always fallacious when intended to influence our beliefs but they are sometimes reasonable when they aim to motivate us to act.
Commonplace Book – Pages 95-96
Bad Company Fallacy: Guilt by Association is the attempt to discredit an idea based upon disfavoured people or groups associated with it. This is the reverse of an ‘Appeal to Authority,’ and might be justly called ‘Appeal to Anti-Authority.’ An argument to authority argues in favor of an idea based upon associating an authority figure with the idea, whereas Guilt by Association argues against an idea based upon associating it with disruptive people or groups.
Bad Reasons Fallacy: This fallacy consists in arguing that a conclusion is false because an argument given for it is bad. It is most likely to occur in the course of a debate, when one side argues badly for the truth of the preposition, and the other side uses the bad argument as a reason to conclude that the proposition is false.
The Base Rate Fallacy: People who have only generic information tend to use it to judge probabilities, which is the rational thing to do since that’s all they have to go by. In contrast, when people have both types of information, they tend to make judgments of probability based entirely from specific information, leaving out the ‘base rate’ or ‘type I’ information. This is the fallacy.
Biased Sample: A fallacy affecting statistical inferences. Since the strength of statistical inferences depend upon the similarity of the sample of population, they are really a species of argument from analogy, and the strength of the inference varies directly with the strength of the analogy. Thus, a inference will commit this fallacy of the similarity is too weak. Two ways: a) the sample is too small to represent population = subfallacy of Hasty Generalization b) the sample is biased in some way as a result of not having been chosen randomly.
Black or White Fallacy: A validating form of argument. Usually, the truth-value of premises is not a question of logic, or common sense. So, while an argument with a false premise is unsound, it’s usually not considered fallacious. However, when a disjunctive premise is false for specifically logical reasons, or when the support for it is based upon a fallacy, then the argument commits this fallacy.
Card-Stacking: A one-sided case presents only evidence favoring its conclusion, and ignores or downplays the evidence against it. In inductive reasoning, it is important to consider all of the available evidence before coming to a conclusion. However, a defense attorney may present one-sided argument for defense and likewise a prosecutor will present biased evidence for conviction; but together they create a non-one-sided argument.
Fallacy of the Consequent: “If P then Q. Therefore, if Q then P.” One of Aristotle’s 13 fallacies. People commit this fallacy because they think the consequence is convertible. Also, when people base opinions just by sense-perception as Aristotle put it: ‘people think honey is bile, because honey is also yellow.’
Complex Question: ‘Plurium Interrogationum‘ A question with a false, disputed, or question-begging presupposition. For example the question, ‘Have you stopped beating your wife?’ presupposes that you have beaten your wife prior to the asking, as will as that you have a wife. If you are unmarried or have never beaten your wife, then the question is loaded.
Composition: Some properties are such that, if every part of a whole has the property, then the whole till too. However, not all properties are like this, for example atoms. All visible objects are made of atoms, which are too small to see. If P is an expansive property, then the argument form above is validating, but definitions of what such a property is. However, if P is not expansive, then the argument is non-validating, and any argument of that form commits this fallacy.
The Conjunction Fallacy: The probability of a conjunction is never greater than the probability of its conjuncts. In other words, the probability of two things being true can never be greater than the probability of one of them being true, since in order for both to be true, each must be true.
Converse Accident: This is a fallacy of generalizing about a population based upon a sample which is too small to be representative. If the population is heterogeneous, then the sample needs to be large enough to represent the population’s variability. With a completely homogeneous population, a sample of one is sufficiently large, so it’s impossible to put an absolute lower limit on sample size. Rather, sample size depends directly upon the variability of the population: the more heterogeneous a population, the large the sample required.
Commonplace Book – Pages 89-91 – 93-95
Fallacy of Accent: A written word could be ambiguous in a way that depended on how it was accented in speech. That is, some words are homographs but not homophones. Example: ‘resent’
Fallacy of Accident: a.k.a. ‘A dicto simplicitor ad dictum secundum quid‘ – Occurs when one either attempts to apply such a rule of thumb to an obviously abnormal instance, or when one treats the rule itself as if it were an exceptionless universal generalization, rather than a defensible rule of thumb.
Affirming the Consequent: Arguments of this form are invalid. Informally, it means that arguments of this form do not give good reason to establish their conclusions, even if their premises are true. Example: ‘If P, then Q. Q. therefore, P.’
Affirmative Conclusion from a Negative Premise: Any form of categorical syllogism with an affirmative conclusion and at least one negative premise. Example: ‘All judges are politicians. Some lawyers are not judges. Therefore, some lawyers are politicians.’
Affirming a Disjunct: A non-validating form of argument when ‘or’ is inclusive, as it is standardly interpreted in prepositional logic. But in order to accuse an argument of committing this fallacy, we must determine in which sense the ‘or’ in the first premise is used.
Ambiguity: A a feature of language, ambiguity occurs when a word or phrase has more than one meaning. As a logical fallacy, Ambiguity occurs when linguistic ambiguity causes the form of an argument to appear validating when it is not.
Ambiguous Middle: Any valid form of categorical syllogism with an ambiguous middle term. A categorical syllogism is an argument with three categorical terms occurring within it. ‘Term’ is to be understood in a semantic sense, so that a single word may ambiguously stand for two terms. This leads to the possibility of ambiguous syllogisms in which one of the words equivocates on two terms.
Amphiboly: Linguistically, an amphiboly is an ambiguity which results from ambiguous grammar, as opposed to one that results from the ambiguity of words or phrases. The fallacy of Amphiboly occurs when a bad argument trades upon grammatical ambiguity to create an illusion of cogency. Example: ‘The panda eats, shoots, and leaves.’
The Anecdotal Fallacy: The Availability Heuristic. ‘The easier it is to remember a type of event, the more likely it is that an event of that type will occur.’ However this leads to fallacies as unusual events do happen. The fallacy is using a recent memory, unusual event or a striking anecdote to lead one to overestimate the probability of events of that type occurring.
Argument by Consensus: ‘Argumentum ad Populum‘ – ‘Idea A is popular, therefore idea A is correct.’ It is committed whenever one argues for an idea based on an irrelevant appeal to its popularity.
Appeal to Misleading Authority: ‘Argumentum ad Verecundiam‘ – We often rely upon expert opinion when drawing conclusions about technical matters where we lack the time or expertise to form an informed opinion. Experts are human beings, after all, and human beings err. This is why on major matters, you should get a second or even third opinion.
Appeal to Celebrity: Since most celebrities are actors or sports stars, they are seldom experts on the products or causes that they endorse. Another problem is that most celebrities who endorse products are paid to do so, and thus the endorsement is not a disinterested one.
Appeal to Consequences: ‘Argumentum ad Consequentum‘ – Arguing that a proposition is true because belief in it has good consequences, or that it is false because belief in it has bad consequences is often an irrelevancy. One can tell that the fallacy is being committed because the consequences do not follow from the proposition itself, but only from belief in it. Example: A child’s belief in Santa may have good consequences, but this has nothing to do with whether there really is a Santa.
Appeal to Force: ‘Argumentum ad Baculum‘ – As a logical fallacy, it applies to the use of force and, by extension, the use of threats of force to ‘win’ a debate. Attempts to change people’s minds by threats are appeals to consequences, since the bad consequences appealed to are not consequences of what is believed, but of the belief itself. Also force used to suppress the arguments of one side in a debate, that is a type of -one-sidedness.
Appeal to Ignorance: ‘Argumentum ad Ignorantiam‘ – ‘There is no evidence against P. Therefore, P.’ An appeal to ignorance is an argument for or against a proposition on the basis of a lack of evidence against or fot it. If there is positive evidence for the conclusion, then of course we have other reasons for accepting it, but a lack of evidence by itself is no evidence.
Appeal to Nature: ‘Argumentum ad Naturam‘ – The problem is that the concept of nature is vague. The vagueness of the notion of naturalness does not mean that it is useless, since there are many clearcut cases of the natural and unnatural. However, an appeal to nature which is based on a borderline case will be unsound because it will be unclear whether its premise is true or false. Sometimes, people associate ‘natural’ with ‘good’ and this is a fallacy. To treat the rule of thumb as if it were an exceptionless generalization is to commit a fallacy.
Argument Against the Man: ‘Argumentum ad Hominem‘ – A debater commits this fallacy when he/she introduces irrelevant personal premises about his opponent. Such attacks may successfully distract the opponent or audience from the topic of the debate.
Argument of the Beard: This is based upon the claim that a controversial type of action will lead inevitably to some bad type of action. The argument is by no means fallacious, but the strength of the argument is inversely proportional to the number of steps between A and Z, and directly proportional to the causal strength of the connections between adjacent steps. If there are many intervening steps, and the causal connections between them are weak or unknown, then the resulting argument will be weak or fallacious.