Why is it important for us as vegans to be good skeptics as well? Carl Sagan, in his book The Demon Haunted World, writes about the process scientists must go through during their Ph.D. oral examinations. “There is much warm and inspired encouragement of apprentice scientists by their mentors. But the poor graduate student at his or her Ph.D. oral exam is subjected to a withering crossfire of questions from the very professors who have the candidate’s future in their grasp. Naturally the students are nervous; who wouldn’t be? True, they’ve prepared for it for years. But they understand that at this critical moment, they have to be able to answer searching questions posed by experts. So in preparing to defend their theses, they must practice a very useful habit of thought: They must anticipate questions; they have to ask: Where in my dissertation is there a weakness that someone else might find? I’d better identify it before they do.”
We vegans may not be preparing for our Ph.D. oral examinations, but as advocates for veganism, we face a similar crossfire of questions. Those who consume animal products and whose worldviews may be challenged by our ideas are not simply going to let go of what they believe because we tell them to. They are going to ask searching, difficult questions and seek out every possible weakness they can that could explain our objections away in a way that seems most reasonable with what they already believe to be true. If we fail to anticipate others' objections we do not risk having our degrees denied, but we do risk losing a potential vegan and further turning their opinion against considering veganism.
What does it mean to be a good skeptic?
A good skeptic recognizes our tendency to seek out evidence that is in line with our desires. As vegans, we most likely want to hear that a vegan diet is healthy. If we are to be good skeptics hearing information that reinforces this hope, particularly from other vegans, should throw up red flags for us. We should require a higher standard of evidence if anything in favor of our hopes and actively seek out any existing evidence in contradiction of the claim, because this is exactly what our critics are going to do.
A good skeptic is also someone who admits uncertainty where it exists and tries to accurately quantify uncertainty based upon the quality of the evidence. This means when evidence is presented for a hypothesis, they will try to find alternate hypotheses that explain that evidence and judge how much more probable or improbable those alternate hypotheses may be, all the while understanding that there may be other explanations that they have not yet thought of. Recently a study came out linking antibodies to a particular viral infection to obesity in children with those antibodies. This was largely reported as “viral infection may be cause of obesity”, yet many other reasonable explanations for this evidence exist. Perhaps parents who allow their children to be obese are also more likely to expose them to certain diseases. Perhaps obesity makes children more prone to certain infections. Perhaps the study just happened to get a strange sample and the results are not representative of the population as a whole. Similarly, suppose we were to hear that vegans have lower rates of lung cancer. Before jumping on the bandwagon and proclaiming that veganism prevents lung cancer, a good skeptic may want to know if vegans are less likely to smoke than the population as a whole.
A good skeptic recognizes fallacies in thinking. We may have a tendency to distrust claims from people or groups that we find untrustworthy, but just because something comes from an untrustworthy source doesn't necessarily mean it is wrong. If we want to claim that they are wrong, we still must make sure that the evidence against their claim actually exists. This is just one of countless examples of fallacious thinking however. Suppose we were to do a study looking at cancer rates among vegans and we find that in our sample we looked over a hundred different types of cancers, and find that for six of them vegans had significantly lower incidences of those cancers at a 95% confidence level. We cannot conclude from this evidence that vegans have lower incidences of those six cancers. This is an example of the Texas sharpshooter fallacy. We have looked at a mass of scattered evidence and then simply picked out those which happened to look like a pattern in our favor. If we wish to actually test whether vegans have lower incidences of those cancers, we must pose our hypothesis beforehand and then get a sample and see how strong the evidence is to support the hypothesis. Keep in mind, if we do not do this, those who currently disagree with us most certainly will, because finding a hole in our thinking will seem much more reasonable to them then having to significantly alter their worldview.
For a list of logical fallacies: http://en.wikipedia.org/wiki/List_of_logical_fallacies
For a toolkit to use as part of being a good skeptic: http://www.youtube.com/watch?v=eUB4j0n2UDU