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Open Minds and the Argument from Ignorance


Jonathan E. Adler

Skeptical Inquirer Volume 22.1, January / February 1998

Arguments from ignorance fallaciously infer that since a hypothesis has not been disproved, it is reasonable to believe that hypothesis or regard it with an open mind.

At the start of the jury’s deliberations in the 1957 film Twelve Angry Men, a straw poll yields eleven “guilty” votes and one “not guilty” vote. The lone juror, played by Henry Fonda, concerned that conviction on a murder charge not be hasty, says defensively, “Supposing we're wrong . . . ,” to which another juror responds indignantly, “Supposing we're wrong? Suppose this building should fall down on my head! You can suppose anything.”

My sympathies are with the second juror. In fact, throughout the first third of the movie Fonda’s character repeatedly appeals to mere suppositions and possibilities, typically without the least attempt, as he often admits, to back them up as at all probable.

The character’s reasoning conforms to the argument from ignorance, standardly classified as a fallacy. Admittedly, Fonda’s character is the hero. He eventually convinces his co-jurors, and rightly so we are led to think, that their initial quick and prejudicial judgment of guilt was wrong. But the result is only a minor embarrassment. If good reasoning can be put to ill use, bad reasoning can be put to good. The argument from ignorance is one of the most prevalent in defending beliefs that starkly conflict with scientific findings.

As many readers will know, in 1992 a conference on alien abduction was held at MIT. The conference was covered by a well-regarded journalist, C. D. B. Bryan, who avows nonbelief in alien abduction, and the resulting work was published by one of the best publishing houses (Bryan 1995). After the Abduction Study Conference, Bryan conducted extensive interviews. At the end of a chapter reporting his interviews with two of the most credible “experiencers,” he reasons:

During the days immediately following the conference, I am struck by how my perception of the abduction phenomenon has changed: I no longer think it a joke. This is not to say I now believe UFOs and alien abduction are real -- “real” in the sense of a reality subject to the physical laws of the universe as we know them -- but rather that I feel something very mysterious is going on. And based as much on what has been presented at the conference as on the intelligence, dedication, and sanity of the majority of the presenters, I cannot reject out-of-hand the possibility that what is taking place isn't exactly what the abductees are saying is happening to them. And if that is so, the fact that no one has been able to pick up a tailpipe from a UFO does not mean UFOs do not exist. It means only that UFOs might not have tailpipes. As Boston University astronomer Michael Papagiannis insisted, “The absence of evidence is not evidence of absence.” (Bryan 1995, 230)

Bryan explicitly denies concluding that alien UFOs are real. In effect, then, Bryan is denying that his reasoning even constitutes argument. Moreover, if there is a conclusion, it is only for the “possibility” that the abductees’ stories are correct, and that appears so weak a judgment that argument hardly seems called for.

Elsewhere, Bryan asks an investigator “why he thinks there is such resistance within the psychiatric and scientific community to even the possibility that the source of the trauma is what the abductees are saying” (Bryan 1995, 268). By contrast to those communities, Bryan characterizes his position as one of open-mindedness. He ends his book:

Still, until someone comes forward with proof that such beings don't exist, I intend to continue keeping an eye out for their “bobbers” [a metaphor for any solid indicator of alien presence] — and, yes, an open mind. (Bryan 1995, 448-449)

So Bryan’s conclusion, if such it be, is extremely weak. He is not arguing that the alien abduction stories should be believed or accepted or even thought probable.

Nevertheless, Bryan is offering an argument -- an argument from ignorance -- broadly of the following kind:

  1. No one has disproved p (where p stands for any hypothesis, e.g., psychics are able to communicate with the dead; some alien abduction accounts are true).
  2. So it is possible that p is true.
  3. If it is possible that p is true, then we should keep our minds open to the investigation of p's truth.

Conclusion: We should keep our minds open to the investigation of p's truth.

Premises 1 and 3 are implicitly assumed by Bryan and are typical of arguments from ignorance. Premise 2 Bryan explicitly states. The conclusion is implied by the premises, as well as stated by Bryan elsewhere. Bryan appeals as well to the credibility of the reports, which does not enter the structure I present, but I'll return to it later.

Others draw much bolder conclusions. Specifically, on similar grounds, it is sometimes inferred that it is reasonable to believe p. However, there will be many cases in which if no one has disproved p, then no one has disproved its contradictory, not-p (e.g., no alien abduction accounts are true). But then the argument would license the inconsistent belief that both p and not-p are true.

The crucial term in the reasoning is possible. My main criticism is this: The sense in which premise 2 is true, or can at least be granted, is far too weak for the conclusion.

In one usage, to hold that it is “possible” that the reports of alien abductions are correct is to hold that the reports are compatible with our evidence (i.e., “not impossible”). This is very weak. In this usage, as the second juror appreciates, it is possible that if I jump off the World Trade Center, I will be saved by a freak wind that lands me safely on the ground. In another usage, to hold that it is “possible” that the reports of alien abductions are correct is to hold that their truth is a serious possibility -- that we shouldn't disbelieve them and their study is worthwhile.

The plausibility of the reasoning trades on this ambiguity. When we are inclined to think it unreasonable to reject the possibility that alien abduction reports are correct, we are treating it as bare possibility. After all, we think, it isn't impossible. Consistent with our evidence, the reports could be true, even if vastly improbable.

But in order to claim that we should keep an open mind, we need the stronger notion of serious possibility. For only then do we have reason not to disbelieve alien abduction reports and to take the reports as even prima facie credible. Though my being saved by a freak wind after jumping from the World Trade Center is possible in the weak sense, it is not at all credible. We reject it out of hand.

The conclusion of open-mindedness also is meant to have the strong implication that we should not treat the absence of evidence as evidence of absence. In fact, the phrase “absence of evidence” is a misnomer. For absent evidence is real evidence. It is the evidence of a failure to detect expected effects of a hypothesis, and so it is evidence against the hypothesis.

In Conan Doyle’s Sherlock Holmes story ”Silver Blaze,” the absence of evidence of the dog’s barking is the clue that someone who knows the dog well, like its trainer or master, is the culprit. Since the expected effects (the dog’s barking) of the hypothesis (that the criminal is a stranger) are not detected, there is genuine undermining evidence against it.

Still, the undermining import of the absence of evidence can be overriden. If there is evidence (not the mere possibility) of the dog’s being drugged, that would override the inference. Defenders of the alien abduction reports do seem to offer overriding evidence or reasons of two kinds. First, they rely on the reports of the alleged abductees; second, they offer conjectures for why the expected effects are undetected.

The first kind of reason is indicative that we never find a pure argument from ignorance. To so label an argument is not only pejorative, but tendentious. But I stand by it. The label involves a simplification of a complex presentation, but it will pay off in illuminating an important strand of reasoning.

As is typical, there are always some phenomena, some disturbing reports, some mysteries that cry out for explanation. But if we are to treat these as credible evidence, they must survive confrontation with other available, relevant evidence. Otherwise, to rely on the puzzling observations and reports alone may be unrepresentative or biased, and so misleading.

Very briefly, standing against the reports of alleged alien abductees is the vast evidence of the established physical laws that would have to be violated or strained. The criterion goes back to David Hume (Hume 1977 [1748]). Aside from the most obvious failure of extensive scientific studies to detect any intelligent organisms outside Earth, regular visits of aliens assume possibilities for space travel at speeds close to, if not exceeding, the speed of light. We also have credible alternative (psychological) explanations for the reports.

In fact, in the passage cited earlier (Bryan 1995, 230), Bryan makes no real attempt to balance the credibility of the reports against the massive weight of standard evidence and alternative explanations. In the remainder of his book, he does make attempts to do so, though of a very scattershot sort. The main suggestion, instead, is that we be moved by the credibility of the "experiencers” alone.

However, the second tack is to offer explanations that lend credence to the abductee accounts. Following the lead of the investigators, Bryan offers a simple speculation:

. . . just because UFOs and their occupants defy our laws of physics does not mean there are not further laws of physics we have not as yet discovered or do not as yet comprehend. . .

(Bryan 1995, 422)

Additionally, he attempts to explain away the absence of evidence by positing vast, unprecedented conspiracies to suppress reports of sightings on the part of otherwise highly competitive and diverse reporters, government officials, and scientists.

These sweeping assumptions are themselves at one with the argument from ignorance. When we grant ourselves blank-check assumptions, we move away from serious possibility to bare possibility. For the more we assume against what is already believed or accepted or well confirmed, the less plausible is our hypothesis. The plausibility that aliens have visited Earth, however low, is still much higher than that they do so regularly, virtually undetected, by means that involve the violation of our laws of nature and a conspiracy to silence a story of immense interest.

We should not set these assumptions aside as a heuristic whose only purpose is to facilitate a fair hearing for the abductee reports. They are essential to whether an open mind on the hypothesis is deserved. For, recall, these assumptions are pivotal for overriding the powerful evidence for rejecting alien abduction stories as false, including evidence of absence.

The request to keep an open mind appears mild, but it is a wolf in sheep’s clothing. “Open-minded” trades upon the same ambiguity we found in the use of "possible.”

The open mind being called for is an openness to any hypothesis that has the bare possibility of truth. Why shouldn't we be so open? Why do we need the notion of serious possibility in the first place? Wouldn't our search for the truth only be improved by not restricting in advance what hypotheses we consider?

The answer is that our time and resources are limited. There are vastly more hypotheses possible (consistent with our evidence) than can be studied. Closed-mindedness, in the sense of ruling out vast numbers of hypotheses prior to examination, is a precondition of any serious empirical inquiry.

Yet, no hypothesis is forever banned. We may subsequently reconsider, as has often occurred in science, a hypothesis once thought ridiculous. But when we do, there will be a preliminary stage in which we find it minimally plausible.

Of course, we each put aside time for hobbies and idle pursuits. In these terms, one may keep up with the literature on UFOs, the paranormal, and related subjects, and even investigate them on one’s own. The interest and pursuit does not require any positive attitude, not even an open mind, in the strong sense that the argument from ignorance requires. (Indeed, it is just because there are a few devoted “fringe-watchers” that the rest of us can, in all intellectual honesty, both ignore new fringe claims and still be sure that our dismissal is warranted. For the lack of reports by reputable researchers favoring these claims is continuing, profound evidence against them. Once again the absence of evidence for is powerful evidence against.)

How is my objection to the relevance of bare possibility to be squared with the banality that the findings of science are fallible? Actually, the fallibility of science is greatly exaggerated. But without going out on that limb (and tangent), let me focus on a premise directly relevant to my criticism. There is a difference between admitting that one may be wrong, which is to acknowledge one’s fallibility, and treating that possibility of error as a genuine reason to doubt. If one does treat fallibility as a genuine reason, one is arguing from ignorance. Our ignorance that we are certainly correct is taken as a reason to withdraw from belief.

Obviously, no one normally so reasons. I could possibly be mistaken that my sister lives in Long Island. But it is not the slightest reason to believe that she doesn't live there.

An exception is when one is engaged in discussion of radical skepticism, the venerable philosophical view that no one knows or has any reason to believe anything. My final three claims about arguing from ignorance are these: First, arguing from ignorance is a disguised radical skepticism; second, when one so reasons, one falsely represents what one believes; and third, arguing from ignorance appears plausible, aside from the ambiguous uses of “possible” and "open mind,” because we fail to appreciate the intimate connection between belief, truth, and evidence. These are large claims and space is limited, so argument will be abbreviated and somewhat dogmatic.

First, it is a disguised radical skepticism. We appear to be talking of a specific hypothesis, such as that the alien abduction tales should not be dismissed. However, the underlying reasoning casts doubts far wider. We do not appreciate that the flip side of this positive conclusion to keep an open mind is a severe negative result. If the mere possibility that a hypothesis is correct is a reason not to dismiss it, then, by parity of reasoning, the mere possibility of error is a reason to doubt. The latter is, effectively, radical skepticism. For anything we believe, we have reason to doubt it simply by virtue of our fallibility.

Second, given these radical implications, arguments from ignorance are in conflict with what people truly believe. But these implications are not always apparent. Consequently, it is not always evident that the conclusions of an argument from ignorance conflict with what everyone, the arguer included, generally believes. No one truly doubts that they are sitting in front of their fireplace simply because it is possible that they may be dreaming it. (Descartes introduced this famous doubt in the appropriate context of his radical inquiry. But even he immediately worried. These doubts, genuine though he takes them to be at this stage of his inquiry, remain helpless to prevent his continued belief in all that is evident to him.)

Third, arguments from ignorance treat beliefs as attitudes that we can adjust to human interests, hopes, and aspirations. If a hypothesis is not proven false, then it is permissible to believe it. But the result cannot be a belief. For a belief is an attitude toward a hypothesis as a correct representation. In a slogan: Beliefs aim at truth. (For a good discussion see Williams 1973.) It is because our beliefs are our attitudes toward truth that they guide action. If we want to quickly get to a destination by train, we rely on our memories (beliefs) as to the train schedules and station locations. Our action succeeds if, and usually only if, the guiding beliefs are correct.

Our beliefs are likely to be correct if they arise from reliable sources. For hypotheses, the main source is evidence. What counts as evidence for a hypothesis are those observed phenomena whose existence depends upon the truth of the hypothesis and so attest to it.

Once I recognize the evidence for a hypothesis as adequate to establish it, I believe it; and conversely, if the evidence refutes the belief. When neither occurs, I suspend judgment.

A medieval challenge is to try to believe the proposition “The number of stars is even” (Burnyeat 1983). It is a challenge we must fail, though it is surely possible that the statement is true. We can only suspend judgment, exactly in accord with the evidence being manifestly indecisive. No choice or option to believe is available, self-deception aside.

What truly marks an open-minded person is the willingness to follow where evidence leads. The open-minded person is willing to defer to impartial investigations rather than to his or her own predilections. It is here that the nineteenth-century American pragmatist Charles Peirce finds the scientific method an advance over other methods for determining (fixing) belief, such as appeal to authority, tenacity, or a priori reasoning. Scientific method is attunement to the world, not to ourselves:

To satisfy our doubts, therefore, it is necessary that a method should be found by which our beliefs may be determined by nothing human, but by some external permanency. . .

(Peirce 1957, 24)

If the evidence against alien abductions and many other supernatural and paranormal speculations is overwhelming, then an open-minded person must reject them.


Jonathan E. Adler

Jonathan E. Adler is professor of philosophy at Brooklyn College and the Graduate Center of the City University of New York, Brooklyn, New York 11210.