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Sagan, Prediction, and Debate

I am currently reading The Demon-Haunted World. Science As A Candle In The Dark by Carl Sagan. It is the first time I have read it and though I had heard much about it, the book still surprised me. It really is one of the most well written, easy to understand, profound, and essential books I have ever read.

In the spirit of this blog however, I want to discuss two statements made by Sagan:

Not every branch of science can foretell the future—paleontology can't—but many can and with stunning accuracy. If you want to know where the next eclipse of the Sun will be, you might try magicians or mystics, but you'll do much better with scientists. They will tell you where on Earth to stand, when you have to be there, and whether it will be a partial eclipse, a total eclipse, or an annular eclipse. They can routinely predict a solar eclipse, to the minute, a millennium in advance.

You can go to the witch doctor to lift the spell that causes your pernicious anemia, or you can take vitamin B12. If you want to save your child from polio, you can pray or you can inoculate. If you're interested in the sex of your unborn child, you can consult plumb-bob danglers all you want (left-right, a boy; forward-back, a girl-or maybe it's the other way around), but they'll be right, on average, only one time in two. If you want real accuracy (here, 99 percent accuracy), try amniocentesis and sonograms. Try science. (Sagan 1996) p30

Accuracy really does matter in science as does predicting the future. Sagan is right when he says that not every branch of science is concerned with prediction, but those that claim to be able to predict the future should be judged by whether they succeed. There is no shame in not predicting the future. Like Sagan says, paleontology does not, scientists doing research regarding convergent evolution do not, indeed the historical sciences in general do not. Different disciplines excel at different things and use different methods and processes.

However, every scientific discipline should be honest and say: “This is what we do and that is not what we do.” Furthermore, every discipline should use words and concepts in accordance with science in general. I realize that different disciplines have different nuances for words and concepts. This is an unfortunate but true state of affairs. But that is quite different from using the word predict to mean getting the right answer occasionally when the rest of science (the biological sciences at least) uses math formulas vis-à-vis sensitivity, specificity, positive and negative predictive value when quantifying predictive ability.

Science is a wonderful thing that human stumbled onto many centuries ago and more scientists should be outraged that vivisection activists are corrupting the core of science in order to keep their jobs and feed their egos.

Sagan again:

Again, the reason science works so well is partly that built-in error-correcting machinery. There are no forbidden questions in science, no matters too sensitive or delicate to be probed, no sacred truths. That openness to new ideas, combined with the most rigorous, skeptical scrutiny of all ideas, sifts the wheat from the chaff. It makes no difference how smart, august, or beloved you are. You must prove your case in the face of determined, expert criticism. Diversity and debate are valued. Opinions are encouraged to contend—substantively and in depth. (Sagan 1996) p31

Again, Sagan is absolutely right. Science does have built-in error-correcting mechanisms and they work. Nevertheless, it can take a very long time to correct errors and there are reasons for this. Impediments to this error-correcting mechanism include lack of technology, lack of knowledge about various aspects of the field, and unfortunately, the following.

1. Arguments from authority, which I covered in Argument From Authority. Part I, Part II and Part III and which Sagan refers to he says: “It makes no difference how smart, august, or beloved you are.” This is related to the famous quote from Max Planck that states: "...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."  (Planck 1948)

2. Acting as if certain questions imply that the questioner is anti-science, which goes against what Sagan says about there being no forbidden questions.

3. Using fallacious reasoning to sell nonsense and falsehoods to an unsuspecting public. See The Usual Fallacies Used by Vivisection Activists, Fallacies Galore, and Fallacious Reasoning.

4. Money and ego. Self-explanatory.

5. Refusal to debate. I have discussed this many times. Debate about scientific principles and content is best accomplished in the scientific literature. I have presented this option to Drs Ringach and Gorski, among many others, all of whom have declined. As I have said before, ceteris paribus, their unwillingness to engage in debate in the scientific literature provides a prima fascia case that I am right and their position wrong. Granted, all other things are never equal, but considering all the time that Gorski, Ringach, and others have put into defending their position online, it is unreasonable to assume that they have no interest in the subject or that they are not in fact making a very strong claim. The fact that they refuse to debate in a forum where debate really counts is telling.

Furthermore, they even refuse to debate in public forums where rules can be enforced and moderators and judges present. The reason I want public debates, in part, is that I cannot get them to debate the topic in the scientific literature. By asking for public debates their disingenuousness can be exposed. (I know it is hard to believe, but the entire world does not regularly read my blogs, therefore more people would be exposed to these ideas through a number of public, university-based debates.) Society needs to be educated regarding the inability of animal models to predict human response to drugs and disease. Saying, as the vivisection activists do, that animals are used in other ways is fallacious as the topic is not the other ways they are used but rather whether they are predictive for human response to drugs and disease. Changing the topic is a tactic of those with a weak position.

Moreover, debate is not vivisection activists debating each other in the scientific literature or on television. Debate on any topic involves those on both sides of an issue not just those on the same side but who have minor differences among themselves. The issue of animal models being predictive for human response to drugs and disease has not been debated by those who state or imply that animal models can be so used and qualified scientists like Dr Shanks and myself, who say they cannot. There have been debates between so-called animal advocates who agree that animal models are predictive and vivisection activists who also state that animal models are predictive. They have been very nice debates and the debaters have all been very happy. Why shouldn’t they be? They all agree. These types of debates are not what Sagan was referring to when he said: “Diversity and debate are valued. Opinions are encouraged to contend—substantively and in depth.” (For more on this see How animal protection groups are delaying the end of vivisection.)

In response to Sarah Greene’s editorial (Greene 2010) in The Scientist, Edward Draper of the Boise, Idaho Veterans Administration Medical Center wrote the following:

The core issues [of animal-based research] are not the degree of predictability of animal research as applied to humans . . . The issues have to do with the relative weight given to conflicting values: the cost of human effort, material resources, animal suffering, etc. to purchase some (or any) useful data for the benefit of society at large, as compared to the benefit of avoiding human suffering by the production of such data. (Emphasis added.)

While I personally disagree with the way Draper has framed the argument, I have never denied that there is an ethical component to using animals in research and in science in general. But when claims are made that animals are predictive then such claims, like all claims about the material world, are subject to scrutiny and the claimant/scientists are expected to debate the claims with experts in the field. Shanks, Jean Greek, and I have had no response to our article Are animal models predictive for humans? Neither have Jean and I had any to our article Is the use of sentient animals in basic research justifiable? The journal Philosophy, Ethics, and Humanities in Medicine is a perfect forum for such a debate yet no one has responded to the articles. No one has accepted an invitation to do a point-counterpoint debate in the literature either. If this were happening in any other scientific discipline there would an uproar from scientists as well as skeptics.

In addition, when the basis for the position that it is ethical to use animals in research rests on the claim that animal models can predict human response to drugs and disease and are thus saving lives (and that is the claim), then such a claim becomes the focus of both the scientific and ethical arguments regarding the use of animals in research.

As I have also said many times, if scientists, skeptics, animal advocates and so forth do not think animals are predictive for disease and drug response, all they have to do is say so. As long as they remain silent, I hear their position loud and clear.


Greene, Sarah. 2010. We Must Face The Threats. The Scientist 24 (11):13.

Planck, Max. 1948. Wissenschaftliche Selbstbiographie. Mit einem Bildnis und der von Max von Laue gehaltenen Traueransprache. Leipzig: Johann Ambrosius Barth Verlag.

Sagan, Carl. 1996. The Demon-Haunted World. Science As A Candle In The Dark. New York: Ballantine Books.


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