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Slothful Induction and Ad Hoc Escapism

Slothful induction, also known as the a priori fallacy, is the failure or refusal to see or concede the most likely inference from the evidence. The failure to infer is rarely due to sloth. It demonstrates an unwillingness to follow the evidence wherever it may lead due to stupidity, dogma, or vested interests. Usually it is a red flag that someone is not principally interested in the truth of a matter. And, because inductive arguments are at best probabilistic, someone can always hold out against the preponderance of evidence. Nevertheless, there are times when it is appropriate to resist the inference of even a good inductive argument, namely, when there are countervailing reasons that support the contrary conclusion. For example, when new evidence appears against a well-established scientific theory, it can be appropriate to retain the current theory until the evidence to the contrary is sufficiently strong. In such cases an ad hoc hypothesis may be introduced to explain how the established thesis may still be true in spite of the implications of this new inductive evidence.


From Thick Headedness

The second fitness-enhancing cognitive capacity is the tendency to recognize that things that are similar to each other with respect to their observed properties are likely to be similar with respect to their unobserved properties… This capacity is advantageous because the principle it is centered around is true, and failure to reason in accordance with the principle can be deadly. Failure to infer that these round, shiny, bright berries are likely to be poisonous from the fact that those other round, shiny, bright red berries produced frothing at the mouth and then death in one’s companion yesterday may well lead to trouble for oneself today.

Wielenberg, God and the Reach of Reason, p. 90

Smith believes an open flame can ignite gasoline (he uses matches to light bonfires, etc.), and Smith believes the match he now holds has an open flame (he would not touch the tip, etc.), and Smith is not suicidal. Yet Smith decides to see whether a gasoline tank is empty by looking inside while holding the match nearby for illumination. Similar stories often appear in newspapers; this is approximately how one of Faulkner’s characters, Eck Snopes, dies in The Town.”

Cherniak, Minimal Rationality, p. 57.) » See the Darwin Awards for more inductive failures of this sort.

From Vested Interests

As the scientific evidence linking lung cancer to smoking mounted in the 1950s and following, tobacco companies consistently resisted and repudiated the evidence. For example, the Brown & Williamson Tobacco Corporation stated: “It is our opinion that the repeated assertion without conclusive proof that cigarettes cause disease — however well-intentioned — constitutes a disservice to the public.” And, the Tobacco Institute of Hong Kong: “The view that smoking causes specific diseases remains an opinion or a judgment, and not an established scientific fact.” (Agin, Junk Science, p. 89.) » Here we have a clear case where economic interests prevented the admission of an overwhelmingly probable conclusion. Notice how these statements capitalize on the nature of inductive arguments, that they are at best probabilistic and never, strictly speaking, conclusive.

I will never accept the news of aspartame safety. I think it is a “business” decision to discredit/discount the research results that aspartame DOES cause cancer, major nerve disorders, birth defects, and brain imbalances. Think about it — can you imagine the chaos that will occur when the truth of aspartame dangers is accredited. The FDA has known about the dangers, the corporations have known about the dangers, and the medical community (if it is really worth anything) has known about the dangers.

Dr. Janet Starr Hull at, emphasis added, cited at Science Based Medicine

In political campaigns, as the election nears, even when a candidate is clearly behind in all the polls, if asked, the candidate or his or her representatives will invariably deny the almost inevitable outcome. This response is understandable and pragmatic. If said candidate’s supporters lose hope, they are less likely to trouble themselves to cast their vote on election day, and the outcome will be even more lopsided and the slim chance for an upset slips even further out of reach.

Ad hoc Escapism

It is possible that a materialistic explanation of consciousness might be found, but that does not make the claim that consciousness is non-physical an argument from ignorance… At any given time, scientists should infer the best current explanation of the available evidence, and right now, the best evidence from both neuroscience and rigorous philosophical analysis is that consciousness is not reducible to the physical. Churchland’s refusal to draw this inference is based not on evidence, but on what Karl Popper called “promissory materialism,” a reliance on the mere speculative possibility of a materialistic explanation. Since this attitude can be maintained indefinitely, it means that even if a non-materialist account is correct (and supported by overwhelming evidence), that inconvenient truth can always be ignored. Surely the project of science should be one of following the evidence wherever it leads, not of protecting a preconceived materialist philosophy.

Menuge, Evangelical Philosophical Society Blog, Oct, 23, 2008.

“Once upon a time two explorers came upon a clearing in the jungle. In the clearing were growing many flowers and many weeds. One explorer says, ‘Some gardener must tend this plot.’ The other disagrees: ‘There is no gardener.’ So they pitch their tents and set a watch. No gardener is ever seen. ‘But perhaps he is an invisible gardener,’ the Believer says. So they set up a barbed-wire fence. They electrify it. They patrol with bloodhounds. But they hear no shrieks that would suggest some intruder had received a shock. No movements of the wire ever betray an invisible climber. The bloodhounds never give a cry. Yet still the Believer is not convinced: ‘But there is a gardener, invisible, intangible, insensible to electric shocks, a gardener who comes secretly to look after the garden which he loves.’ At last the Skeptic despairs: ‘But what remains of your original assertion? Just how does what you call an invisible, intangible, eternally elusive gardener differ from an imaginary gardener or even from no gardener at all?'”

Smith, Ethical and Religious Thought in Analytic Philosophy of Language, p. 24.

In an historical instance of the left hand not knowing what the right hand is doing, Albert Einstein’s General Theory of Relativity had already predicted that the universe was either expanding or contracting. Unfortunately, Einstein found the notion so distasteful that he had introduced a “fudge factor,” a variable called a cosmological constant, theoretically retrofitted to keep the universe in steady, eternal equilibrium. But upon learning of Hubble’s discovery, Einstein made a widely publicized trip to California to see Hubble’s data for himself. As a result of Hubble’s discoveries, and the works of Georges Édouard Lemaître, a Belgian Roman Catholic priest and physicist who had studied under Arthur Eddington, and Soviet Aleksandr Friedmann — whose solutions to Einstein’s theory implied an expanding universe — he repented of his cosmological constant, famously calling it the “greatest blunder” of his career.

Gonzalez, Guillermo; Richards, Jay W.. The Privileged Planet: How Our Place in the Cosmos Is Designed for Discovery (pp. 170-171). Regnery Gateway. Kindle Edition.


With the possible exception of Orwellian measures, it’s generally impossible to force someone to change their mind, and this is a very good thing. About all you can do is 1) revisit the evidence and point to the strength of the inference. 2) If there are additional sources of evidence that can be brought to bear, one should do so and mount a cumulative case for the conclusion. 3) To ascertain whether it is even worth arguing, ask: “If this evidence does not persuade you, what would constitute sufficient evidence to change your mind?” For example, the author at Ebon Musings takes this tack against biblical inerrantists who refuse to acknowledge apparent contradictions as real contradictions.

I accused Mr. Holding and his inerrantist ilk of being trapped in a mindset that will simply not allow the Bible to be wrong, no matter how obvious the error or inconsistency, and posed them the following question: ‘What would it take to convince you that you were wrong? What, hypothetically, would the Bible have to say to be contradictory? Can you give an imaginary example of two discrepant verses that you would accept as impossible to resolve?'”

It’s worth remembering that though someone may be unwilling to concede a point at the moment or in public, they may very well be moved by the evidence privately or in subsequent reflection. Though, to save face, people are disinclined to make an about face, they are also, as Doug Geivett puts it, “naturally truth-interested and exquisitely evidence-sensitive”.

Rhetorically, for the sake of the audience in a discussion or public debate, it can be effective to rehearse and press the point. “So just to be clear, we have seen that for these reasons there is strong evidence that this is the most likely conclusion. You refuse to concede the point but haven’t given us any good reason for not following this evidence where it leads.” This approach reminds the audience of the evidence and draws attention to an opponent’s recalcitrance toward the truth of the matter.


“Study” and Statistic Skepticism

There is Benjamin Disraeli’s famous adage, popularized by Mark Twain, that: “There are three kinds of lies: lies, damned lies, and statistics.” Similarly, talk radio host Dennis Prager often says, roughly paraphrased: “Studies are almost always either wrong or merely tell us what we already know.” The first quote is motivated by the ease with which statistics can be manipulated both in the gathering and in the presentation in order to validate foregone conclusions. Prager’s view is motivated by a deference to wisdom gathered from ordinary human experience. I confess a deep skepticism towards statistics and studies for all of these reasons, particularly because of how often the integrity of these studies is compromised by the ideological agenda of those who commission them. As a rule, I disregard the steady stream of studies that make headlines by purportedly overturning conventional wisdom, at least until they are scrutinized more closely. Though they have an air of scientific credibility, I have far too often seen such studies undermined after the fact, almost always buried in the backpages instead of on the cover where the study’s provocative conclusion first appeared. (See here, here, and here.) Epidemiologist Ben Goldacre summarizes the subtle enterprise of evaluating medical and therapeutic studies in his TED talk, “Battling Bad Science“. Goldacre observes wryly the ongoing project of sensationalistic news sources to divide “all the inanimate objects in the world into the ones that cause or prevent cancer”.

As I have noted before – you have to interpret a literature, not a single study. The results of one lab or one study can be erroneous. When decades have produced hundreds of studies on a question, the cherry pickers will always have a lot to choose from. That is why systematic reviews are necessary, and it is also necessary to understand the strengths and weaknesses of each type of research.

Steven Novella in “Aspartame — Truth and Fiction

Though skepticism is in order, statistics and studies can hardly be ruled out of court. The world is not always as it seems; it is not flat, and heavier objects fall no faster than lighter objects. Moreover, many questions of vital importance can only be addressed by evidence gathering and experiment. Is this pharmaceutical drug effective in ameliorating or curing a malady? Is the charity to which I’m giving using effective methods for diminishing poverty? Do some forms of incarceration encourage less recidivism than others? As is appropriate with inductive evidence, skepticism can be met with more evidence, with confirmation from additional studies from other sources. The Education Commission of the States outlines some tools in evaluating studies. Withholding judgment can be appropriate, but at some point, as the evidence mounts, the failure to concede what it implies most assuredly merits the charge of “slothful induction”.

Failing to Infer from New and Conflicting Evidence

In his influential work, The Structure of Scientific Revolutions, Thomas Kuhn argues that when a scientific theory becomes well established, it enjoys a period of “normal science” wherein the theory is taken for granted and its implications fleshed out through its application to further questions. During this time, discoveries of data that might serve to disconfirm the theory are largely devalued, attributed to methodological errors. However, if that anomalous data persists and grows, and if there is a corresponding cultural shift that is less amenable to the theory in question, the theory enters a stage of crisis, of “revolutionary science”, the outcome of which is often the emergence of a new paradigm. With relevance to failures of inference, the initial resistance to disconfirmation can be seen here as appropriate when the established theory earned its status for good reasons. Pearcey and Thaxton make this point as part of their argument that the relationship between Christianity and science has been more friendly than antagonistic.

Let us be the first to acknowledge that Christians have often opposed new ideas in science. But let us also point out that this is not some perverse failing of religious people but a universal human tendency. All people tend to resist new ideas. Nor is that necessarily a failing. After all, as long as an idea remains new, its supporters generally have not yet mustered the necessary support for it. (Pearcey & Thaxton, The Soul of Science, p. 40.)

Stephen C. Meyer points out that in many cases this resistance to anomolous data has proven to be a real asset.

Consider, for example, falsifiability. As Imre Lakatos has shown some of the most powerful scientific theories have been constructed by those who stubbornly refused to reject their theories in the face of anomalous data. On the basis of his theory of Universal Gravitation, Newton, for example, made a number of predictions about the position of planets that did not materialize. Nevertheless, rather than rejecting the notion of universal gravitation he refined his auxiliary assumptions (e.g. the assumption that planets are perfectly spherical and influenced only by gravitational force) and left his core theory in place. As Lakatos has shown, the explanatory flexibility of Newton’s theory in the face of apparently disconfirming evidence turned out to be one of its greatest strengths. Such flexibility was emphatically not a token of “non-scientific status” as the Popperian model would suggest.

(“The Use and Abuse of Philosophy of Science” in Perspectives on Science & Christian Faith: The Journal of the American Scientific Affiliation, 46, no. 1)

There is a real danger here, however. There is a temptation to dismiss anomalous data indefinitely, walling off a theory from even the possibility of falsification. This recalcitrance diminishes the extent to which the theory can be considered sensitive to evidence. John Searle takes this to be the state of affairs in contemporary discussion of consciousness.

The materialist tradition is massive, complex, ubiquitous, and yet elusive. Its various elements — its attitude toward consciousness, its conception of scientific verification, its metaphysics and theory of knowledge — are all mutually supporting, so that when one part is challenged, the defenders can easily fall back on another part whose certainty is taken for granted. Here I speak from personal experience. When you offer a refutation of strong AI or of the indeterminacy thesis or of functionalism, the defenders do not feel it necessary to try to meet your actual arguments, because they know in advance that you must be wrong. (Searle, The Rediscovery of the Mind, p. 9.)

Doug Geivett offers another example, highlighting J.L. Mackie’s resistance to the implications of the inductive evidence for a beginning of the physical universe. He perceives an unwillingness to follow the evidence where it leads based on Mackie’s prior commitment to a naturalistic worldview. Notice also how Geivett appeals to
supplementary philosophical evidence in the face of resistance to the inference.

“Mackie never actually commits himself to the view that the material universe has an absolute but uncaused beginning. At times he even seems agitated by the scientific confirmation of an absolute beginning of the universe. Thus, he is willing to say that to the extent that a sheer unexplained beginning of things seems
improbable, this very improbability “should cast doubt on the interpretation of the big bang as an absolute beginning of the material universe.” In other words, he would rather wait it out for some future internally self-explanatory naturalistic model of cosmology than allow that the universe began to exist: “We should infer that it must have had some physical antecedents.” It is, however, not always prudent to withhold judgment until further evidence becomes available, and it is not very intellectually honest to stubbornly withhold judgment on the mere wish that further evidence should one day become available. Moreover, it has already been argued that there are also good philosophical reasons for thinking that the universe had a beginning.” (Geivett, Evil and the Evidence for God, p. 105.)

Ad Hoc

For the sake of naturalism, Mackie suggest we should “infer” — i.e. postulate — a “physical antecedent”. This brings us to the common strategy of resisting an inference by appealing to an ad hoc supposition. The supposition is called “ad hoc” because it is not grounded on independent evidence, but postulated as a logical possibility just in order to save a theory. Apparently even Ptolemaic astronomy can be reconciled with contemporary astronomical data if given free reign to postulate as many epicycles as needed. The problem is that virtually any theory can be saved when given this much latitude. And, of course, we’re not primarily interested in what might possibly be true, but rather what is probably true.

One example of an ad hoc supposition is the multiverse thesis, most often proposed to rebuff the potentially teleological implications of the fine-tuning of the universe. In recent decades with our growing awareness of the remarkably narrow physical constants necessary for life, the classic design argument for the existence of God has become all the more compelling to some. In response, atheists frequently defer to the logical possibility that ours is but one of a countless array of universes. For example, Richard Dawkins adopts this strategy in The God Delusion. “This objection can be answered by the suggestion… that there are many universes, co-existing like bubbles of foam, in a ‘multiverse’.” (p. 144) Because we do not have independent evidence for either of these suppositions, Dawkins acknowledges them to be ad hoc, but justifies the move based on the principle of simplicity:

It is tempting to think (and many have succumbed) that to postulate a plethora of universes is a profligate luxury which should not be allowed. If we are going to permit the extravagance of a multiverse, so the argument runs, we might as well be hung for a sheep as a lamb and allow a God. Aren’t they both equally unparsimonious ad hoc hypotheses, and equally unsatisfactory? … The multiverse, for all that it is extravagant, is simple. God, or any intelligent, decision-taking, calculating agent, would have to be highly improbable in the very same statistical sense as the entities he is supposed to explain. The multiverse may seem extravagant in sheer number of universes. But if each one of those universes is simple in its fundamental laws, we are still not postulating anything highly improbable.” (pp. 146-7)

Another arena in which ad hoc reasoning may be in play is in theistic responses to the argument from evil, particularly when that response is in the form of a theodicy. It is instructive in this context to compare theistic responses to the deductive and inductive versions of this argument. Most philosophers believe the deductive version to have been put to rest by Alvin Plantinga in God, Freedom, and Evil. He argues that there are least logically possible reasons that would justify God’s allowing suffering and evil, namely the intrinsic worth of libertarian free will with respect to moral evil, and a battle between angelic and demonic forces with respect to natural evil. While these possibilities may not strike the skeptic as especially probable, because the deductive argument from evil sets for itself the high bar of logical necessity, alternate logical possibilities — ad hoc though they may be — are sufficient to defeat the argument. Accordingly, the discussion has moved to an inductive form, where it is argued that while the existence of God is not logically impossible, it is quite unlikely.

The inductive argument from evil proceeds something like: 1) There are evils that either in their tremendous quantity or horrific quality are gratuitous — i.e. without justification — on the face of it. 2) We cannot conceive of any reason that an omniscient, omnipotent, omnibenevolent God would permit such apparently gratuitous cases of evil and suffering so there probably isn’t any reason. 3) So, there probably is no God as such. In response to this form of the argument, it will not do just to posit any logically possible justification for God permitting evil, however wildly improbable. If a particular evil really seems gratuitous, it probably is if the only alternative is extremely improbable.

One approach is to propose a theodicy in response, a possible justification for God allowing the kinds of evil we find in the world. John Hick, for example, offers what has been called a “soul-making” theodicy. God allows suffering and evil because by rising to the challenge of alleviating suffering and contending with evil, human souls are formed in such a way that they couldn’t be had we been placed in a harmless paradise. Though perhaps this is possible, we might ask whether this supposition is more probable than not, more probable then there being no justification for a particular evil for which there seems to be no soul-making benefit. Because of the difficulty of demonstrating the probability of a given theodicy, in Evil and the Evidence for God, Doug Geivett argues that an essential corollary to theodical proposals is an evaluation of whether there is independent evidence for the existence of God.

A theodicy, it is often thought, is supposed to show what justifying reasons God actually has for permitting evil. But theodicies are not generally convincing to nontheists impressed by the reality of evil. So where does this leave matters? Are we at an impasse? I do not think so, if we have recourse to natural theology. I propose that the theist should appeal directly to the resources of natural theology in response to the challenge from evil. (p. 60)

In spite of the reality of evil, Geivett suggests that if we have independent evidence for the existence of God, then a theodicy is considerably more plausible. Indeed, if we have good reasons to believe both that evil exists and God exists, we can assume that some justification exists even if we don’t know what it is. But, apart from such independent evidence for God, any particular theodicy might strike us as improbable, as ad hoc escapism.

The reason for this extended discussion of the role of ad hoc suppositions in resisting an inference has been to illustrate that it is not always clear that “slothful induction” is out of place. In some cases, one might concede that a certain set of inductive evidence supports a particular conclusion without granting that conclusion. Specifically, it is appropriate when there are independent reasons for disbelieving the conclusion, that is to say, when there is conflicting evidence. The more comprehensive a theory, as in the cases of theism and naturalism, the more likely such disparate evidence will surface. Philosopher Paul Draper, for example, takes the relevant evidence for theism and for naturalism to be sufficiently disparate and incommensurable to justify agnosticism. But, if resisting an inference can be justified in the face of roughly balanced conflicting evidence, it must also be said that doing so should be avoided whenever possible. If we are to be honest seekers after truth, we must not ignore or deny evidence merely because it subverts our cherished beliefs. May we be neither too hasty nor too slothful in inferring the implications of the evidence.