What is rationality?

(Paper presented by Tim Harding at Mordi Skeptics meetup, 1 February 2011. An edited version was published in The Skeptic magazine, Vol. 36 No. 4, December 2016)

What do we skeptics mean when we say that a belief is irrational?  How do we define rationality and irrationality?  Are there any objective tests of an irrational belief?

First, some definitions.  Most dictionaries define rationality as the state or quality of being rational.  Not a lot of help.  So what does it mean to be rational? Once again, most dictionaries define rational as being consistent with or based on or using reason,[1] which is further defined as the mental ability to draw inferences or conclusions from assumptions or premises (the ‘if – then’ connection).  The application of reason is known as reasoning; the main categories of which are deductive and inductive reasoning.[2]

Reason is thought by rationalists to be more reliable in determining what is true; in contrast to reliance on other factors such as authority, tradition, instinct, intuition, emotion, mysticism, superstition, faith or arbitrary choice (e.g. flipping a coin).  For example, we rationally determine the balance in our cheque book (between bank statements) by adding up the credits and subtracting the debits and bank fees.  An irrational way of doing it would be to pick a number at random – not very reliable, and any correct answer would be a mere coincidence, rather than the product of reasoning.

The ancient Greeks thought that rationality distinguishes humans from other animals.  ‘Man is a rational animal’ as Aristotle said.[3]  However, this distinction is becoming blurred by recent research indicating that other primate species such as chimpanzees can show a limited use of reason and therefore a degree of rationality.

The word rational can be used in several different contexts; for example rational behaviour (psychology), rational or optimal decision (economics); a rational process (science), and rational belief (philosophy).  However, it is not the purpose of this paper to discuss all uses of rationality – only those relevant to our use, that is, skepticism.

I would suggest that the context most relevant to skepticism (which could be described as a form of applied philosophy) is that of rational belief, because we skeptics often criticise the beliefs of paranormals, quacks, cults and pseudo-sciences on the grounds that they are irrational (which, of course, is the antonym of rational).[4]  However, the scientific context of a ‘rational process’ is also relevant to skepticism; and I will say more about this later.

In my view, the relevance of rational belief to skepticism is that we use it as a filter to determine what we should be skeptical about.  We skeptics are not necessarily skeptical of everything.  We believe what it is rational to believe, and we are skeptical of beliefs that are known to be or appear to be irrational.  That is why I think it is important for skeptics to clarify and understand the nature of rational belief.

Harvard philosophy professor Robert Nozick has proposed two criteria for rational belief:

  1. support by reasons that make the belief credible; and
  2. generation by a process that reliably produces true beliefs.[5]

Two thought experiments

I would now like to try a couple of little thought experiments.

Firstly, imagine if you will a primitive tribe in the remote mountains of New Guinea.  The chief of this tribe needs to predict whether or not it is going to rain tomorrow[6] so he can decide whether the men will go hunting or not.  So he consults the local witch doctor, who according to long tradition slaughters a chicken and examines the configuration of the dead chicken’s entrails.  Using this information, the local witch doctor then predicts that will not rain tomorrow.  Is this a rational belief?

In terms of Nozick’s criteria, we would probably say that this belief is irrational because it is neither supported by reasons that make the belief credible, nor is it generated by a process that reliably produces true beliefs.

But what if this local witch doctor’s predictions, using the chicken entrail process, have always been right?  In that case, it could be argued that the process meets Nozick’s criterion No. 2.  It could also be argued that because the New Guinea tribe have no school education, and believe that rain and the configuration of a chicken’s entrails are caused by the same spirit, that the reasons for the witch doctor’s predictions are credible to them.  Does this alter our assessment of the rationality of this belief?  Perhaps it does.

What if exactly the same process is used by a hippie commune in Nimbin, where hippies have had the benefit of a school education and therefore should be aware that there is no credible causal connection between the incidence of rain and the configuration of a chicken’s entrails.  Do these different circumstances alter our assessment of whether the belief is rational?  Perhaps they do again.

Secondly, until early December 2010, it was believed by the scientific community (and published in reputable peer-reviewed scientific journals) that the element arsenic is toxic to all life on Earth in even very small concentrations.[7]  However, NASA-supported researchers have discovered the first known microorganism on Earth able to thrive and reproduce using arsenic.  The microorganism, which lives in California’s Mono Lake, substitutes arsenic for phosphorus in some of its cellular components.[8]  Prior to this announcement by NASA, was it rational to believe that arsenic is toxic to all life on Earth in even very small concentrations?  In terms of Nozick’s criteria, the answer would be ‘yes’, even though we now know that belief was false.  Was it rational to hold this belief after the NASA announcement?  Given that the NASA scientific announcement is credible and was generated by reliable scientific processes, our answer would be ‘no’.

By these two thought experiments, I have tried to show how a rational process can lead to a belief which may be rational in certain contexts or circumstances and yet turn out to be false.  So truth is not necessarily an adequate test of a rational belief.  In other words, a rational belief is not necessarily true, and an irrational belief is not necessarily false.  On the other hand, a rational belief needs to be reasonable or credible in the circumstances; that is, a rational belief is one that is justified by reason.

Although an irrational belief is not necessarily false, we can say that because an irrational belief is unreliable and more likely to be false than a rational belief, we should therefore be more skeptical about beliefs that are known to be or appear to be irrational than about rational beliefs.

It is believed by some philosophers (notably A.C. Grayling) that a rational belief must be independent of emotions, personal feelings or any kind of instincts.  Any process of evaluation or analysis, that may be called rational, is expected to be objective, logical and ‘mechanical’.  If these minimum requirements are not satisfied i.e. if a person has been influenced by personal emotions, feelings, instincts or culturally specific, moral codes and norms, then the analysis may be termed irrational, due to the injection of subjective bias.

So let us now look at some other possible objective tests of irrational belief, including logical fallacies, emotional or faith-based rather than evidence-based beliefs, beliefs based on insufficient supporting evidence, beliefs derived from confirmation bias, beliefs incompatible with science and internally incoherent beliefs, and any others we would like to discuss at this meetup.

Logical fallacies

A logical fallacy is faulty reasoning in argumentation resulting in a misconception.  A fallacious argument can be deductively invalid or one that has insufficient inductive strength.  For example, the argument that smoking does not cause cancer based on the anecdotal evidence of only one healthy smoker.

By accident or design, fallacies may exploit emotional triggers in the listener or interlocutor (e.g. appeal to emotion), or take advantage of social relationships between people (e.g. argument from authority).  By definition, a belief arising from a logical fallacy is contrary to reason and is therefore irrational.

Emotional, instinctive or faith-based rather than evidence-based beliefs

In western literature, reason is often opposed to emotions or instincts — desires, fears, hates, drives, or passions.  Even in everyday speech, westerners tend to say for example that their passions made them behave contrary to reason, or that their reason kept the passions under control, often expressed in colloquial terms as the dilemma between following ‘the head’ (reason) ‘or the heart’ (emotions).

Faith involves a stance toward some claim that is not, at least presently, demonstrable by reason.  Thus faith is a kind of attitude of trust or assent. As such, it is ordinarily understood to involve an act of will or a commitment on the part of the believer.  People do not usually have faith in something they do not want to believe in.  Religious faith involves a belief that makes some kind of either an implicit or explicit reference to a transcendent source.  The basis for a person’s faith usually is understood to come from the authority of revelation.[9]  Faith-based belief without evidence is considered to be a virtue by the religiously devout; but a ‘sin’ by rationalists.

Emotional, instinctive and faith-based beliefs are held on grounds other than evidence or reason, and according to the definitions given in the first part of this paper are irrational.  This is not to say that such beliefs are necessarily wrong, bad or undesirable – simply that they are not derived from reason.

Though theologies and typically do not claim to be irrational, there is often a perceived conflict or tension between faith and tradition on the one hand, and reason on the other, as potentially competing sources of wisdom and truth.  Defenders of traditions and faiths typically maintain that there is no real conflict with reason, because reason itself is not enough to explain such things as the origins of the universe, or right and wrong, and so reason can and should be complemented by other sources of knowledge.  The counter claim to this is that there are actual conflicts between faith and reason (for instances, the Trial of Galileo, creationism vs evolution, stem-cell research etc).

Some relatively recent philosophers, most notably the logical positivists, have denied that there is a domain of thought or human existence rightly governed by faith, asserting instead that all meaningful statements and ideas are accessible to thorough rational examination.[10]

Insufficient supporting evidence

Some beliefs are not necessarily based on emotion or faith, and are not entirely devoid of evidence, but there is insufficient evidence to justify the belief.  Beliefs in UFOs, alien abductions and conspiracy theories such as the so-called Moon Landings Hoax fall into this category.

Confirmation bias – cherry-picking the evidence

Confirmation bias is a tendency for people to favour information that confirms their preconceptions or hypotheses regardless of whether the information is true.  As a result, people gather evidence and recall information from memory selectively, and interpret it in a biased way.  The biases appear in particular for emotionally significant issues, for established beliefs and for conspiracy theories.

For example, there is some evidence that in a very small number of cases there are adverse reactions to some vaccines in some patients.  But this argument against vaccination overlooks the overwhelming benefits of vaccination in preventing and in some cases eradicating infectious diseases.  In other words, the anti-vaccination campaigners do not take into account evidence contrary to their fixed beliefs.  Thus the beliefs of anti-vaccination campaigners and some conspiracy theorists are based on faulty reasoning; and are therefore irrational.

 Incompatibility with science

It has long been held that rationality requires rigorous rules for deciding whether a proposition should be believed.  Formal logic and mathematics provide the clearest examples of such rules.  Science has also been considered a model of rationality because it proceeds in accordance with scientific methods which provide the rules for gathering evidence and evaluating hypotheses on the basis of this evidence.[11]

One of the main purposes of scientific methods is to eliminate subjective biases and interfering factors in order to test hypotheses.  This is why scientists use techniques such as controls and double blind tests that we often hear about in sceptical discussions.

Where a belief is incompatible with science, either the belief must be false or the science must be wrong – they can’t both be right.  For example, homeopathy is incompatible with the science of chemistry; water-divining is incompatible with the science of physics and astrology is incompatible with the science of astronomy.  On this ground alone, pseudo-sciences like these are irrational.

Internally incoherent beliefs

Coherentism is a theory of epistemic justification.  It implies that for a belief to be justified it must belong to a coherent system of beliefs. For a system of beliefs to be coherent, the beliefs that make up that system must “cohere” with one another.  In other words, some of a person’s justified beliefs are justified because they derive their justification from other beliefs.  For example, take my belief that tomorrow is Wednesday.  That belief can be justified by two other beliefs: my belief that today is Tuesday and my belief that Tuesday is immediately followed by Wednesday.  But, if my belief that tomorrow is Wednesday derives its justification from these other beliefs, then my belief that tomorrow is Wednesday is justified only if these other beliefs are justified.[12]  If today is Monday, then my belief that tomorrow is Wednesday is incoherent and unjustified.

For example, the claim of homeopathy that ‘like cures like’ is incoherent with the practice of diluting substances to the point where there is nothing but water in a homeopathic dose.  Homeopathy makes no sense, or in other words is internally incoherent and therefore irrational.  We can all probably think of other paranormal and pseudo-science beliefs that are internally incoherent and therefore irrational.

Summary

In summary, rationality is the state or quality of being rational, which means as being consistent with or based on or using reason.

Reason is thought by rationalists to be more reliable in determining what is true; in contrast to reliance on factors such as authority, tradition, instinct, intuition, emotion, mysticism, superstition faith or arbitrary choice.

The word rational can be used in several different contexts; but the context most relevant to skepticism is that of rational belief, because we use it as a filter to determine what we should be sceptical about.  We skeptics are not skeptical of everything.  We believe what it is rational to believe, and we are skeptical of irrational beliefs.

Two criteria have been proposed by Nozick for a rational belief:

  1. support by reasons that make the belief credible; and
  2. generation by a process that reliably produces true beliefs.

A rational belief is not necessarily true, and an irrational belief is not necessarily false.  On the other hand, a rational belief needs to be reasonable or credible in the circumstances; that is, a rational belief is one that is justified by reason.  It needs to pass objective tests of irrationality.

Objective tests of irrational belief include logical fallacies, emotional or faith-based rather than evidence-based beliefs, beliefs based on insufficient supporting evidence, beliefs derived from confirmation bias, beliefs incompatible with science, internally incoherent beliefs and possibly other tests.

Although an irrational belief is not necessarily false, we can say that because an irrational belief is unreliable and more likely to be false than a rational belief, we should therefore be more skeptical about beliefs that are known to be or appear to be irrational than about rational beliefs.

References:

Fieser, J. and Dowden, B. eds (2011) Internet Encyclopedia of Philosophy <http://www.iep.utm.edu/>

Honderich, T. ed (2005) The Oxford Companion to Philosophy, 2nd edition. Oxford University Press, Oxford.

Nozick, R. (1993) The Nature of Rationality, Princeton University Press, Princeton.


[1] Meaning reason in the philosophical sense as defined here, rather than in the colloquial sense of a reason meaning any explanation for an action or event, whether or not the explanation is based on reason in the philosophical sense.

[2] Deductive vs inductive reasoning is a possible topic for a future meetup?

[3] Nozick, 1993 p.xi

[4] The term ‘non-rational’ means neither rational nor irrational, and applies to matters unrelated to truth or falsity such as taste or aesthetics.

[5] Nozick, 1993 p.xiv

[6] For the purpose of this thought experiment, we assume that it does not rain every day and there is no predictable pattern of rainfall in the area in question.

[7] Most chemicals can be toxic in sufficiently large concentrations.

[9] Feiser and Dowden et al, 2011.

[10] Feiser and Dowden et al, 2011.

[11] Honderich et al, 2005 p. 786.

[12] Feiser and Dowden et al, 2011.

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