Logical Fallacies as Bayesian Informational Shortcuts

Information closure may help with the consistency of a database, so it is related to information quality. However, it cannot be used to expand such an information repository. For this, other forms of reasoning are needed. Bayesianism is often indicated as a classic means to upgrade a set of beliefs or indeed some bits of information, in the vocabulary of this book. Some other erroneous forms of reasoning, however, damage the same reservoir of information. Interestingly, the two dynamics are related. As argued in this chapter, the two best known formal logical fallacies, namely denying the antecedent (DA) and affirming the consequent (AC), are not just basic and simple errors, which prove human irrationality, but rather informational shortcuts, which may provide a quick and dirty (and therefore unsafe) way of extracting useful information from the same informational resources to which Alice already has access. And, in this sense, they can be shown to amount to degraded versions of Bayes’ theorem, once this is stripped of some of its probabilities. The less the probabilities count, the closer these fallacies become to a reasoning that is not only informationally useful but also logically valid.