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Against accommodationism: How science undermines religion

The Conversation

Russell Blackford, University of Newcastle

There is currently a fashion for religion/science accommodationism, the idea that there’s room for religious faith within a scientifically informed understanding of the world.

Accommodationism of this kind gains endorsement even from official science organizations such as, in the United States, the National Academy of Sciences and the American Association for the Advancement of Science. But how well does it withstand scrutiny?

Not too well, according to a new book by distinguished biologist Jerry A. Coyne.

Gould’s magisteria

The most famous, or notorious, rationale for accommodationism was provided by the celebrity palaeontologist Stephen Jay Gould in his 1999 book Rocks of Ages. Gould argues that religion and science possess separate and non-overlapping “magisteria”, or domains of teaching authority, and so they can never come into conflict unless one or the other oversteps its domain’s boundaries.

If we accept the principle of Non-Overlapping Magisteria (NOMA), the magisterium of science relates to “the factual construction of nature”. By contrast, religion has teaching authority in respect of “ultimate meaning and moral value” or “moral issues about the value and meaning of life”.

On this account, religion and science do not overlap, and religion is invulnerable to scientific criticism. Importantly, however, this is because Gould is ruling out many religious claims as being illegitimate from the outset even as religious doctrine. Thus, he does not attack the fundamentalist Christian belief in a young earth merely on the basis that it is incorrect in the light of established scientific knowledge (although it clearly is!). He claims, though with little real argument, that it is illegitimate in principle to hold religious beliefs about matters of empirical fact concerning the space-time world: these simply fall outside the teaching authority of religion.

I hope it’s clear that Gould’s manifesto makes an extraordinarily strong claim about religion’s limited role. Certainly, most actual religions have implicitly disagreed.

The category of “religion” has been defined and explained in numerous ways by philosophers, anthropologists, sociologists, and others with an academic or practical interest. There is much controversy and disagreement. All the same, we can observe that religions have typically been somewhat encyclopedic, or comprehensive, explanatory systems.

Religions usually come complete with ritual observances and standards of conduct, but they are more than mere systems of ritual and morality. They typically make sense of human experience in terms of a transcendent dimension to human life and well-being. Religions relate these to supernatural beings, forces, and the like. But religions also make claims about humanity’s place – usually a strikingly exceptional and significant one – in the space-time universe.

It would be naïve or even dishonest to imagine that this somehow lies outside of religion’s historical role. While Gould wants to avoid conflict, he creates a new source for it, since the principle of NOMA is itself contrary to the teachings of most historical religions. At any rate, leaving aside any other, or more detailed, criticisms of the NOMA principle, there is ample opportunity for religion(s) to overlap with science and come into conflict with it.

Coyne on religion and science

The genuine conflict between religion and science is the theme of Jerry Coyne’s Faith versus Fact: Why Science and Religion are Incompatible (Viking, 2015). This book’s appearance was long anticipated; it’s a publishing event that prompts reflection.

In pushing back against accommodationism, Coyne portrays religion and science as “engaged in a kind of war: a war for understanding, a war about whether we should have good reasons for what we accept as true.” Note, however, that he is concerned with theistic religions that include a personal God who is involved in history. (He is not, for example, dealing with Confucianism, pantheism or austere forms of philosophical deism that postulate a distant, non-interfering God.)

Accommodationism is fashionable, but that has less to do with its intellectual merits than with widespread solicitude toward religion. There are, furthermore, reasons why scientists in the USA (in particular) find it politically expedient to avoid endorsing any “conflict model” of the relationship between religion and science. Even if they are not religious themselves, many scientists welcome the NOMA principle as a tolerable compromise.

Some accommodationists argue for one or another very weak thesis: for example, that this or that finding of science (or perhaps our scientific knowledge base as a whole) does not logically rule out the existence of God (or the truth of specific doctrines such as Jesus of Nazareth’s resurrection from the dead). For example, it is logically possible that current evolutionary theory and a traditional kind of monotheism are both true.

But even if we accept such abstract theses, where does it get us? After all, the following may both be true:

  1. There is no strict logical inconsistency between the essentials of current evolutionary theory and the existence of a traditional sort of Creator-God.


  1. Properly understood, current evolutionary theory nonetheless tends to make Christianity as a whole less plausible to a reasonable person.

If 1. and 2. are both true, it’s seriously misleading to talk about religion (specifically Christianity) and science as simply “compatible”, as if science – evolutionary theory in this example – has no rational tendency at all to produce religious doubt. In fact, the cumulative effect of modern science (not least, but not solely, evolutionary theory) has been to make religion far less plausible to well-informed people who employ reasonable standards of evidence.

For his part, Coyne makes clear that he is not talking about a strict logical inconsistency. Rather, incompatibility arises from the radically different methods used by science and religion to seek knowledge and assess truth claims. As a result, purported knowledge obtained from distinctively religious sources (holy books, church traditions, and so on) ends up being at odds with knowledge grounded in science.

Religious doctrines change, of course, as they are subjected over time to various pressures. Faith versus Fact includes a useful account of how they are often altered for reasons of mere expediency. One striking example is the decision by the Mormons (as recently as the 1970s) to admit blacks into its priesthood. This was rationalised as a new revelation from God, which raises an obvious question as to why God didn’t know from the start (and convey to his worshippers at an early time) that racial discrimination in the priesthood was wrong.

It is, of course, true that a system of religious beliefs can be modified in response to scientific discoveries. In principle, therefore, any direct logical contradictions between a specified religion and the discoveries of science can be removed as they arise and are identified. As I’ve elaborated elsewhere (e.g., in Freedom of Religion and the Secular State (2012)), religions have seemingly endless resources to avoid outright falsification. In the extreme, almost all of a religion’s stories and doctrines could gradually be reinterpreted as metaphors, moral exhortations, resonant but non-literal cultural myths, and the like, leaving nothing to contradict any facts uncovered by science.

In practice, though, there are usually problems when a particular religion adjusts. Depending on the circumstances, a process of theological adjustment can meet with internal resistance, splintering and mutual anathemas. It can lead to disillusionment and bitterness among the faithful. The theological system as a whole may eventually come to look very different from its original form; it may lose its original integrity and much of what once made it attractive.

All forms of Christianity – Catholic, Protestant, and otherwise – have had to respond to these practical problems when confronted by science and modernity.

Coyne emphasizes, I think correctly, that the all-too-common refusal by religious thinkers to accept anything as undercutting their claims has a downside for believability. To a neutral outsider, or even to an insider who is susceptible to theological doubts, persistent tactics to avoid falsification will appear suspiciously ad hoc.

To an outsider, or to anyone with doubts, those tactics will suggest that religious thinkers are not engaged in an honest search for truth. Rather, they are preserving their favoured belief systems through dogmatism and contrivance.

How science subverted religion

In principle, as Coyne also points out, the important differences in methodology between religion and science might (in a sense) not have mattered. That is, it could have turned out that the methods of religion, or at least those of the true religion, gave the same results as science. Why didn’t they?

Let’s explore this further. The following few paragraphs are my analysis, drawing on earlier publications, but I believe they’re consistent with Coyne’s approach. (Compare also Susan Haack’s non-accommodationist analysis in her 2007 book, Defending Science – within Reason.)

At the dawn of modern science in Europe – back in the sixteenth and seventeenth centuries – religious worldviews prevailed without serious competition. In such an environment, it should have been expected that honest and rigorous investigation of the natural world would confirm claims that were already found in the holy scriptures and church traditions. If the true religion’s founders had genuinely received knowledge from superior beings such as God or angels, the true religion should have been, in a sense, ahead of science.

There might, accordingly, have been a process through history by which claims about the world made by the true religion (presumably some variety of Christianity) were successively confirmed. The process might, for example, have shown that our planet is only six thousand years old (give or take a little), as implied by the biblical genealogies. It might have identified a global extinction event – just a few thousand years ago – resulting from a worldwide cataclysmic flood. Science could, of course, have added many new details over time, but not anything inconsistent with pre-existing knowledge from religious sources.

Unfortunately for the credibility of religious doctrine, nothing like this turned out to be the case. Instead, as more and more evidence was obtained about the world’s actual structures and causal mechanisms, earlier explanations of the appearances were superseded. As science advances historically, it increasingly reveals religion as premature in its attempts at understanding the world around us.

As a consequence, religion’s claims to intellectual authority have become less and less rationally believable. Science has done much to disenchant the world – once seen as full of spiritual beings and powers – and to expose the pretensions of priests, prophets, religious traditions, and holy books. It has provided an alternative, if incomplete and provisional, image of the world, and has rendered much of religion anomalous or irrelevant.

By now, the balance of evidence has turned decisively against any explanatory role for beings such as gods, ghosts, angels, and demons, and in favour of an atheistic philosophical naturalism. Regardless what other factors were involved, the consolidation and success of science played a crucial role in this. In short, science has shown a historical, psychological, and rational tendency to undermine religious faith.

Not only the sciences!

I need to be add that the damage to religion’s authority has come not only from the sciences, narrowly construed, such as evolutionary biology. It has also come from work in what we usually regard as the humanities. Christianity and other theistic religions have especially been challenged by the efforts of historians, archaeologists, and academic biblical scholars.

Those efforts have cast doubt on the provenance and reliability of the holy books. They have implied that many key events in religious accounts of history never took place, and they’ve left much traditional theology in ruins. In the upshot, the sciences have undermined religion in recent centuries – but so have the humanities.

Coyne would not tend to express it that way, since he favours a concept of “science broadly construed”. He elaborates this as: “the same combination of doubt, reason, and empirical testing used by professional scientists.” On his approach, history (at least in its less speculative modes) and archaeology are among the branches of “science” that have refuted many traditional religious claims with empirical content.

But what is science? Like most contemporary scientists and philosophers, Coyne emphasizes that there is no single process that constitutes “the scientific method”. Hypothetico-deductive reasoning is, admittedly, very important to science. That is, scientists frequently make conjectures (or propose hypotheses) about unseen causal mechanisms, deduce what further observations could be expected if their hypotheses are true, then test to see what is actually observed. However, the process can be untidy. For example, much systematic observation may be needed before meaningful hypotheses can be developed. The precise nature and role of conjecture and testing will vary considerably among scientific fields.

Likewise, experiments are important to science, but not to all of its disciplines and sub-disciplines. Fortunately, experiments are not the only way to test hypotheses (for example, we can sometimes search for traces of past events). Quantification is also important… but not always.

However, Coyne says, a combination of reason, logic and observation will always be involved in scientific investigation. Importantly, some kind of testing, whether by experiment or observation, is important to filter out non-viable hypotheses.

If we take this sort of flexible and realistic approach to the nature of science, the line between the sciences and the humanities becomes blurred. Though they tend to be less mathematical and experimental, for example, and are more likely to involve mastery of languages and other human systems of meaning, the humanities can also be “scientific” in a broad way. (From another viewpoint, of course, the modern-day sciences, and to some extent the humanities, can be seen as branches from the tree of Greek philosophy.)

It follows that I don’t terribly mind Coyne’s expansive understanding of science. If the English language eventually evolves in the direction of employing his construal, nothing serious is lost. In that case, we might need some new terminology – “the cultural sciences” anyone? – but that seems fairly innocuous. We already talk about “the social sciences” and “political science”.

For now, I prefer to avoid confusion by saying that the sciences and humanities are continuous with each other, forming a unity of knowledge. With that terminological point under our belts, we can then state that both the sciences and the humanities have undermined religion during the modern era. I expect they’ll go on doing so.

A valuable contribution

In challenging the undeserved hegemony of religion/science accommodationism, Coyne has written a book that is notably erudite without being dauntingly technical. The style is clear, and the arguments should be understandable and persuasive to a general audience. The tone is rather moderate and thoughtful, though opponents will inevitably cast it as far more polemical and “strident” than it really is. This seems to be the fate of any popular book, no matter how mild-mannered, that is critical of religion.

Coyne displays a light touch, even while drawing on his deep involvement in scientific practice (not to mention a rather deep immersion in the history and detail of Christian theology). He writes, in fact, with such seeming simplicity that it can sometimes be a jolt to recognize that he’s making subtle philosophical, theological, and scientific points.

In that sense, Faith versus Fact testifies to a worthwhile literary ideal. If an author works at it hard enough, even difficult concepts and arguments can usually be made digestible. It won’t work out in every case, but this is one where it does. That’s all the more reason why Faith versus Fact merits a wide readership. It’s a valuable, accessible contribution to a vital debate.

The ConversationRussell Blackford, Conjoint Lecturer in Philosophy, University of Newcastle

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.


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Why should we place our faith in science?

The Conversation

Jonathan Keith, Monash University

Most of us would like to think scientific debate does not operate like the comments section of online news articles. These are frequently characterised by inflexibility, truculence and expostulation. Scientists are generally a little more civil, but sometimes not much so!

There is a more fundamental issue here than politeness, though. Science has a reputation as an arbiter of fact above and beyond just personal opinion or bias. The term “scientific method” suggests there exists an agreed upon procedure for processing evidence which, while not infallible, is at least impartial.

So when even the most respected scientists can arrive at different deeply held convictions when presented with the same evidence, it undermines the perceived impartiality of the scientific method. It demonstrates that science involves an element of subjective or personal judgement.

Yet personal judgements are not mere occasional intruders on science, they are a necessary part of almost every step of reasoning about evidence.

Among the judgements scientists make on a daily basis are: what evidence is relevant to a particular question; what answers are admissible a priori; which answer does the evidence support; what standard of evidence is required (since “extraordinary claims require extraordinary evidence”); and is the evidence sufficient to justify belief?

Another judgement scientists make is whether the predictions of a model are sufficiently reliable to justify committing resources to a course of action.

We do not have universally agreed procedures for making any of these judgements. This should come as no surprise. Evidence is something experienced by persons, and a person is thus essential to relating evidence to the abstractions of a scientific theory.

This is true regardless of how directly the objects of a theory are experienced – whether we observe a bird in flight or its shadow on the ground – ultimately it is the unique neuronal configurations of an individual brain that determine how what we perceive influences what we believe.

Induction, falsification and probability

Nevertheless, we can ask: are there forms of reasoning about evidence that do not depend on personal judgement?

Induction is the act of generalising from particulars. It interprets a pattern observed in specific data in terms of a law governing a wider scope.

But induction, like any form of reasoning about evidence, demands personal judgement. Patterns observed in data invariably admit multiple alternative generalisations. And which generalisation is appropriate, if any, may come down to taste.

Many of the points of contention between Richard Dawkins and the late Stephen Jay Gould can be seen in this light. For example, Gould thought Dawkins too eager to attribute evolved traits to the action of natural selection in cases where contingent survival provides an alternative, and (to Gould) preferable, explanation.

One important statement of the problem of induction was made by 18th-century philosopher David Hume. He noted the only available justification for inductive reasoning is that it works well in practice. But this itself is an inductive argument, and thus “taking that for granted, which is the very point in question”.

Karl Popper wanted science to be based on the deductive reasoning of falsificationism rather than the inductive reasoning of verificationism. Lucinda Douglas-Menzies/Wikimedia

Hume thought we had to accept this circularity, but philosopher of science Karl Popper rejected induction entirely. Popper argued that evidence can only falsify a theory, never verify it. Scientific theories are thus only ever working hypotheses that have withstood attempts at falsification.

This characterisation of science has not prevailed, mainly because science has not historically proceeded in this manner, nor does it today. Thomas Kuhn observed that:

No process yet disclosed by the historical study of scientific development at all resembles the methodological stereotype of falsification by direct comparison with nature.

Scientists cherish their theories, having invested so much of their personal resources in them. So when a seemingly contradictory datum emerges, they are inclined to make minor adjustments rather than reject core tenets. As physicist Max Planck observed (before Popper or Kuhn):

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.

Falsification also ignores the relationship between science and engineering. Technology stakes human lives and personal resources on the reliability of scientific theories. We could not do this without strong belief in their adequacy. Engineers thus demand more from science than a working hypothesis.

Some philosophers of science look to probabilistic reasoning to place science above personal judgement. Prominent proponents of such approaches include Elliot Sober and Edwin Thompson Jaynes. By these accounts one can compare competing scientific theories in terms of the likelihood of observed evidence under each.

However, probabilistic reasoning does not remove personal judgement from science. Rather, it channels it into the design of models. A model, in this sense, is a mathematical representation of the probabilistic relationships between theory and evidence.

As someone who designs such models for a living, I can tell you the process relies heavily on personal judgement. There are no universally applicable procedures for model construction. Consequently, the point at issue in scientific controversies may be precisely how to model the relationship between theory and evidence.

What is (and isn’t) special about science

Does acknowledging the role played by personal judgement erode our confidence in science as a special means of acquiring knowledge? It does, if what we thought was special about science is that it removes the personal element from the search for truth.

As scientists – or as defenders of science – we must guard against the desire to dominate our interlocutors by ascribing to science a higher authority than it plausibly possesses. Many of us have experienced the frustration of seeing science ignored or distorted in arguments about climate change or vaccinations to name just two.

But we do science no favours by misrepresenting its claim to authority; instead we create a monster. A misplaced faith in science can and has been used as a political weapon to manipulate populations and impose ideologies.

Instead we need to explain science in terms that non-scientists can understand, so that factors that have influenced our judgements can influence theirs.

It is appropriate that non-scientists subordinate their judgements to that of experts, but this deference must be earned. The reputation of an individual scientist for integrity and quality of research is thus crucial in public discussions of science.

I believe science is special, and deserves the role of arbiter that society accords it. But its specialness does not derive from a unique mode of reasoning.

Rather it is the minutiae of science that make it special: the collection of lab protocols, recording practices, publication and peer review standards and many others. These have evolved over centuries under constant pressure to produce useful and reliable knowledge.

Thus, by a kind of natural selection, science has acquired a remarkable capacity to reveal truth. Science continues to evolve, so that what is special about science today might not be what will be special about it tomorrow.

So how much faith should you put in the conclusions of scientists? Judge for yourself!

The ConversationJonathan Keith, Associate Professor, School of Mathematical Sciences, Monash University

This article was originally published on The Conversation. (Reblogged by permission) . Read the original article.

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Hitchens on religious instruction

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Hitchens on free inquiry

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Rowan Atkinson on disliking religions



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Hitchens on faith

“Faith is the surrender of the mind; it’s the surrender of reason, it’s the surrender of the only thing that makes us different from other mammals. It’s our need to believe, and to surrender our skepticism and our reason, our yearning to discard that and put all our trust or faith in someone or something, that is the sinister thing to me. Of all the supposed virtues, faith must be the most overrated.” – Christopher Hitchens

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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.


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.


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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