Analyzing the Emerging Democratic Majority Theorem Using Bayes’ Theorem
The Emerging Democratic Majority (EDM) theory states that “demographic and sociological changes are driving the country towards a progressive majority”. The purpose of this article was to test the validity of this theory by analyzing arguments for both sides. The author first begins by stating claims supporting and against the EDM theory, but then he goes into a discussion of Bayes Theorem. He argues that Bayes’ theorem can actually be a useful tool in gauging the validity of the claims on each side. He defines two events E and H. E means that there will be observable evidence supporting the claims that EDM theorists present. H means that there actually is an emerging Democratic majority. He then bases the rest of his discussion of the assumption that P(E|H) = 0.9. This assumption was made because he says the chances of a false negative when there is actually an emerging democratic majority is low. However, he makes an interesting argument that the chances of a false positive, P(E|~H), are different depending on what side of the argument you stand on.
He doesn’t give the numbers to support his calculations, but he says that an EDM theorist would say P(E|~H) = 0.03, a neutral party would say P(E|~H) = 0.1, but a skeptic would say P(E|~H) = 0.5. This is a strong argument because it means that even if there is overwhelming evidence supporting an emerging democratic majority, skeptics will still be ambivalent. The author finally takes a stance and says that he is a skeptic because the cycle of realignment that supports the EDM theory doesn’t seem certain enough. However, the website this article is on is Real Clear Politics, a site that is known to lean towards the right-wing. Perhaps this author has been interacting with other conservatives so often that an information cascade occurred within the right wing that led him to be skeptical of the EDM theory.
Link to article: http://www.realclearpolitics.com/articles/2014/10/28/putting_the_emerging_democratic_majority_theory_to_the_test_124460.html