Critical thinking
Chapter 7
Pseudo-reasoning

Fallacies

Fallacies count as arguments in the sense that they fit our definition of an argument. They consist of a set of propositions, some of which premises, one of which is a conclusion. But, one way or another, they are bad arguments.
A fallacy: a mistake in reasoning.

One commits a fallacy when the reasons advanced or accepted in support of a claim fail to justify its acceptance.
A fallacy can be committed either when one is deciding whether to accept a claim on the basis of a fallacious argument with which one has been presented or when one is presented the fallacious argument oneself.

A fallacious argument or inference: one in which there is an inappropriate connection between premises and conclusion.
Almost all fallacies fall under one of the following two types:

• Formal fallacies: the inappropriate connections are failures of logical connection. The argument of inference is neither deductively valid nor inductively forceful, even where all implicit premises have been made explicit.
• Substantive (or informal) fallacies: the inappropriate connections involve reliance on some very general unjustified assumptions or inferences. We need only make these premises explicit in order to see that they are false and unjustified. The implicit, false or dubious premise will be of a general nature, having nothing specifically to do with the subject matter of the argument.

The majority of fallacies that we encounter in everyday texts and speech are substantive fallacies.

A fallacious argument can have true or false premises.
Simply having false premises does not make an argument fallacious.
Nor does having true premises guarantee that an argument is not fallacious.

A proposition accepted on the basis of a fallacious argument may turn out to be true as a matter of actual fact.

The best way to become acquainted with the different types of fallacies is to practise identifying and analysing them.
As they are attempts to persuade by argument, you need to reconstruct them in standard form and then use techniques of argument analyses and assessment to demonstrate the ways in which they are fallacious.

Many types of fallacious argument are effective as rhetorical ploys.

Formal fallacies

Formal fallacies: patterns of argument whose reasoning makes purely logical mistakes.
Each type of fallacy constitutes an invalid argument.
The fallacies will be recognized by the presence of the particular invalid pattern.

Affirming the consequent of a conditional

Affirming the consequent for short.
This occurs when we argue from the conditional premise that if P (the antecedent), then Q (the consequent) together with the premise that Q to the conclusion that P.

P1) If P then Q
P2) Q
---------------------
C) P

Example:

P1) Is someone is a philosopher, then they are wise
P2) Jon is wise
-----------------------
C) Jon is a philosopher

This is a fallacy!
If the premises were true, the conclusion would not have to be true.

Affirming the antecedent of a conditional premise does not make for an invalid argument.

Denying the antecedent of a conditional

Denying the antecedent for short.
Occurs when we argue form a conditional premise (if P then Q) together with the negation of its antecedent (not-P) for the conclusion that the consequent is also negated (not-Q).

P1) If P then Q
P2) not P
---------------
C) not Q

This is a fallacy!
There are conditions other than P under which Q could be.

The fallacy of deriving ‘ought’ from ‘is’

A prescriptive conclusion cannot be validly derived from purely descriptive premises. Such an inference is fallacious.

The fallacy of deriving an ‘ought’ from an ‘is’: when a prescriptive conclusion (a conclusion making a claim about something that should or ought to be done or avoided or believed or not believed) is deduced solely on the basis of descriptive, fact-stating, premises.

They are fallacious because the fact that something happens to be the case, or happens not to be the case, is insufficient grounds for concluding that it ought or ought not to be the case.

If we want to make a valid argument for a prescriptive conclusion, we must always do so form premises where at least one of them is prescriptive.

The base rate fallacy

Base rate fallacy: when an argument takes the following form:
The proportion of one group that has a certain feature is higher than the proportion of another group that has that feature. Therefore, some X that has that feature is more likely to be from the fist group than the second.

For example:

P1) Most Ringons are green
P2) Few non-Ringons are geen
P3) Apex is green
--------------------------------
C) Probably Apex is a Ringon

Since the argument tells you nothing about the total number of Ringons as compared with non-Ringons, the argument is not inductively forceful. P1-P23 do not give you a reason to infer the conclusion.

Substantive (or informal) fallacies

All the substantive fallacies can be be shown to be fallacious by making explicit the hidden assumption that generates the illegitimate inference.

The fallacy of majority belief

The fallacy of majority belief: concluding, on the basis of the fact that the majority believe a certain proposition, that the proposition is true.

Even if the majority of people do believe a proposition and even if they are sound of character, ect, their believing it is not sufficient to make it true.
We are owed some justification for the claim that is independent of what anyone might believe.

By exposing the hidden assumption generating the fallacy, we reveal that the same (or a very similar) false proposition, usually a generalisation, figures in all instances of a particular fallacy.

The fallacy of majority belief is similar to the rhetorical ploy of appeal to popularity, because both use the fact of something’s popularity or commonality to accept to persuade us to do or believe it.

• To call it a (substantive) fallacy is to say that the argument presented implicitly embodies a certain sort of unjustified assumption
• To call it a rhetorical ploy is to say that it attempts causally to induce us to accept a certain belief by activating our social instincts, desires and fears

Common practice

Common practice: attempting to persuade someone to do something they shouldn’t do by giving them the justification that ‘everyone does it’.
The implication of this faulty reasoning is that if everyone does X, then X must be acceptable.
The fallacy is driven by a false assumption concerning the connection between what is commonly believed or done and what is morally, socially or rationally acceptable to believe or do.

The gambler’s fallacy (aka the Monte Carlo fallacy or the fallacy of the maturity of choices)

The gambler’s fallacy stems form a misunderstanding of the factors that can influence probability.

To expose the fallacy in a reconstruction, we need to make clear the mistaken assumption that an event’s occurring frequently (or infrequently) makes it less likely (or more likely) to happen on the available next occasion.

Ad hominem

Ad hominem can be committed in two ways:

• By responding to someone’s argument by making an attack upon the person rather than addressing to the argument itself
• By rejecting a claim because of disapproval or dislike form the person who makes it.

All instances of the ad hominem fallacy depend on underlying general assumptions referring to certain characteristics or beliefs of arguers.

Ad hominem circumstantial

Ad hominem circumstantial: a sub-species of the ad hominem fallacies that occurs when someone’s argument in favour of doing or believing something is discounted on the grounds that they would allegedly benefit form doing or believing it.

It is unreasonable to reject an argument because the arguer desires or would benefit from the truth of the conclusion. When matters is the strength of the reasons given for the claim, irrespective of the arguer’s motives for making the claim.

The issue of a speaker or a writer’s character is not entirely irrelevant in matters of argument analysis and evaluation.

• A person’s actions are relevant to their credibility: the degree to which someone’s having said something constitutes a reason to think it true.

Although it remains the case that many ad hominem appeals are fallacious, and the ad hominem fallacy is often used to powerful rhetorical effect, when presented with arguments that include a claim about someone’s character, we should bear in mind that there can be non-fallacious arguments that include ad hominem claims.

Tu quoque

The tu quoque (you too) fallacy: when we make unwarranted connections between a person’s alleged lack of credibility and the strenght of their argument.
Here the alleged lack of credibility ensues specifically form heir being hypocritical, from a perceived inconsistency between the arguer’s actions and their claims.
The fallacy is committed when we reject a person’s claim that a behaviour or proposal should be refrained form or discarded on the grounds that they themselves practise that behaviour.
Or when we reject a person’s claim that a behaviour or proposal should be adopted on the grounds that they fail to follow it themselves.

For example the hidden premise: whenever someone’s behaviour is inconsistent with their advice, that advice is false.

Appeal to authority

Appeal to authority: when an argument makes an unjustified appeal to an alleged authority.
This can occur either because the authority appealed to is not in fact authoritative on the matter at hand, or because there is good reason to doubt that the claimed authority is adequately informed of the facts of the matter.
Often the alleged authority will have some association with the matter at hand, but that association is not of a type to make them an authority on the question on which they pronounce.

This does not mean that all appeals to authority are fallacious, only those that are mistaken about someone’s claim to be authoritative about the matter in hand.

The appeal to authority can also function as a rhetorical ploy, the pull of the alleged authority being used to lure us into accepting the proposition being argued for.

The perfectionist fallacy

The perfectionist fallacy: when we place excessive demands on an idea or a proposal and then reject it purely on the grounds that it will not completely solve a problem.
The perfectionist assumption is that no measure aimed at solving or reducing a problem is justified unless it solves or reduces it completely.

Conflation of morality with legality

Conflation of morality with legality: the mistake that assuming that anything legal must be moral or, that anything illegal must be immoral.

The fact that something is legal does not automatically make it morally acceptable!

Weak analogy

Analogies may be illustrative of points one wishes to make, but arguing on the basis of analogy is often unsuccessful and turns out to be fallacious.

• because the analogy is to weak to sustain the argument
• because the analogy itself has not been argued for

The fallacy of weak analogy usually proceeds on the basis of a proposition that because one thing is similar to another in one respect, it is, therefore, similar in a further respect.
This mistaken inference is based on the false assumption that if something is similar to another thing in one respect, it is similar in all respects.

The fact that arguments form analogy frequently turn out to be fallacious does not mean that they are universally unsuccessful.
For an analogy to be effective in giving us a reason to accept a conclusion, an arguer must first present an argument for the claim that the objects that are allegedly analogous are sufficiently similar in the relevant respects.
Once established, this conclusion would become a premise of a subsequent argument for the claim.

Causal fallacies

Causal fallacies: when we make mistaken inferences about the cause(s) of something.
Three types:

• post hoc ergo propter hoc
• the fallacy of mistaking correlation for cause
• inversion of cause and effect

Post hoc ergo propter hoc

• When we mistakenly infer that an event X caused an event Y merely on the basis that Y occurred after X.

The fallacy of mistaking correlation for cause

• When the fact that one type of event or state of affairs is always or usually found in conjunction with another type of event or state of affairs is mistakenly taken to be sufficient to establish that events or states of affairs of one type cause the other.
• When a statistical correlation is assumed, without any further justification, to establish a causal relation.

Inversion of cause and effect

• When one mistakenly infers that if X causes Y, an absence of X will prevent Y.
• Sometimes we encounter the inversion fallacy and the fallacy of mistaking correlation for cause committed simultaneously.

Epistemic fallacies

• Appeal to ignorance

Concluding either that because a claim has not been proven it must be false (the negative form).
Concluding that because it has not been disproven it must be true (positive form)

Of course, in cases where efforts to prove something have been sufficiently strenuous, it may be reasonable to infer the falsity of the proposition.
The mere fact that a proposition hasn’t been proved, just by itself, is no reason to think it is false.
The mere fact that a proposition hasn’t been disproved, just be itself, is no reason to think it true.

• Epistemic fallacy

When we make a fallacious inference from the fact that someone believes that P that they must also believe that Q on the grounds that P and Q are about the same thing or person, even though the way in which they refer to that thing or person is different.
The danger of epistemic fallacies, is that they may attribute beliefs to persons that they do not really hold.

Faulty argument techniques

Both formal and substantial fallacies make for unsound arguments. They are either irremediably invalid, or depend on some very general, but false, implicit assumption.

Now poor techniques of argument.
Many of them are useful for non-rational persuasion.
Although reconstruction will be helpful in analysing instances of these argument techniques, they cannot be exposed by making explicit a false assumption that drives all instances of the technique in question.
There is no single false assumption that underlies all instances of each of these techniques.

Equivocation

The rhetorical ploy of trading on a equivocation: the ploy whereby we deliberately use a word or form of words with the intention to confuse the audience, one hopes that the audience will conflate the two or more possible interpretations.
A single unsupported claim, rather than an argument, may be the instrument of the ploy.

To fall prey to an argument that employs equivocation is to fail to notice an ambiguity, or in some cases an instance of vagueness, thereby accepting the conclusion of an argument when one should not have.

Red herring

Used to throw someone off the scent of one’s argument by distracting them with an irrelevance.
The rhetorical ploy of the smokescreen constitutes of a similar tactic.

• but where an irrelevant premise(s) is given as a reason for accepting the conclusion being advanced, a faulty argument is being used.

The red herring fallacy is that of inferring a conclusion from a premise that is strictly irrelevant to it, but in a way that has the potential to fool the audience into accepting the inference.
Normally this is accomplished by a premise that tends to instil some sort of positive attitude towards the conclusion.

Although red herring arguments can easily be represented as valid, red herring is not a substantive fallacy.
What is and what is not relevant to a conclusion will depend on the conclusion’s particular subject matter.

The ability to recognize red herring arguments varies depending on our knowledge of the subject matter of the argument.

Slippery slope

Slippery slope: when a arguer wrongly assumes that to permit or forbid a course of action will inevitably lead to the occurrence of further related and undesirable events, without providing good reasons to suppose that the further events will indeed inevitably follow, and thus to allow the first is to tread on a slippery slope down which we will slide to the other events.

Its rhetorical power is derived from fear or dislike of the undesirable events, it is form a rhetorical point of view closely related to the appeal of fear.

Of course, some slopes really are slippery, even in this case, it might be possible to give such reasons and they might form part of an extended argument for the same conclusion.

Straw man

Straw man: the technique used when an arguer ignores their opponent’s real position on an issue and sets up a weaker version of that position by misrepresentation, exaggeration, distortion, or simplification.
This makes it easier to defeat, thereby creating the impression that the real argument has been refuted.

Begging the question

An argument is commits the fallacy of begging the question when the truth of its conclusion is assumed by one or more of its premises, and the truth of the premises depend for their justification on the truth of the conclusion.
Thus the premises ask the audience to grant the conclusion even before the argument is given.

An argument’s premise(s) and conclusion need not express a proposition in precisely the same way in order for it to count as an instance of begging the question.
It is sufficient that the premise be a version of, or rely upon, the claim made by the conclusion.

Arguments that beg the question are often referred to as ‘circular reasoning’.

False dilemma

False dilemma: the technique of limiting consideration of positions on an issue to fewer alternatives than are actually to be considered.
Typically, the arguer pretends that there are only two options, when in fact there are more.The arguer sets up a dilemma where none really exists by misrepresenting the possible positions on an issue, so that there appears to be a straight choice between their own and its opposite.

Too much maths!

Confusing absolute and relative difference

Relative risk is only a percentage of the absolute risk.

Marine of error