Logical Fallacies

Traditionally, logicians construed fallacies as mistakes in inference, as things that looked like good (i.e., deductively valid) arguments but were not. Two fallacies stood out like a sore thumb on this view of fallacies: the fallacy of many questions (because it does not even look like a good argument, or any kind of argument) and the fallacy of petitio principii (because it looks like and is a good argument). The latter is the concern of this paper. One possible response is to say that the tradition is right about the concept of fallacy but wrong about its extension: petitio principii is not a fallacy. If the only proper ways to criticize an argument are to say that it is invalid or that it is unsound, and petitio principii is not criticisable on either of these counts, then calling it a fallacy is tantamount to saying we should prefer invalid or unsound arguments Robinson (Analysis, 31(4): 114 ,1971). I will present a third way to logically criticize arguments and show that fallacious instances of petitio principii are so criticisable while other instances of petitio principii are non-fallacious; hence, this fallacy is not a reductio of the Standard Treatment. It is not my intention in this paper to come out on the side of any of the competing theories-the Standard Treatment, the dialectical theories, and the epistemic theories-as general theories of fallacy. I show only that petitio principii can be handled by something closely resembling the Standard Treatment in so far as that, on entirely logistical principles, there can be made a distinction such that circular arguments form at best a degenerate kind of argument. Circular arguments look like good arguments but are not, not because they are deductively invalid (which they are not) but because they do not deserve to be called arguments at all.

The winning entry in David Stove's 1985 Competition to Find the Worst Argument in the World was: “We can know things only as they are related to us/insofar as they fall under our conceptual schemes, etc., so, we cannot know things as they are in themselves.” That argument underpins many recent relativisms, including postmodernism, post-Kuhnian sociological philosophy of science, cultural relativism, sociobiological versions of ethical relativism, and so on. All such arguments have the same form as ‘We have eyes, therefore we can't see’, and are equally invalid.

Recent work on conditional reasoning argues that denying the antecedent [DA] and affirming the consequent [AC] are defeasible but cogent patterns of argument, either because they are effective, rational, albeit heuristic applications of Bayesian probability, or because they are licensed by the principle of total evidence. Against this, we show that on any prevailing interpretation of indicative conditionals the premises of DA and AC arguments do not license their conclusions without additional assumptions. The cogency of DA and AC inferences rather depends on contingent factors extrinsic to, and independent of, what is asserted by DA and AC arguments.

Celebrated for disproving the traditional view that lack of oxygen at birth (perinatal asphyxia) contributes significantly to cerebral palsy, a 1986 New England Journal of Medicine article by Karin Nelson and Jonas Ellenberg engineered a new consensus in the medical community: that lack of oxygen at birth rarely causes cerebral palsy. We demonstrate that the article's central argument relies on straightforwardly fallacious statistical reasoning, and we discuss significant implications -- e.g. how carefully fetuses are monitored during labor and delivery, expert testimony in malpractice cases, and public policy decisions.

Starting with a brief overview of current usages (Sect. 2), this paper offers some constituents of a use-based analysis of 'fallacy', listing 16 conditions that have, for the most part implicitly, been discussed in the literature (Sect. 3). Our thesis is that at least three related conceptions of 'fallacy' can be identified. The 16 conditions thus serve to " carve out " a semantic core and to distinguish three core-specifications. As our discussion suggests, these specifications can be related to three normative positions in the philosophy of human reasoning: the meliorist, the apologist, and the panglossian (Sect. 4). Seeking to make these conditions available for scholarly discussion, this analysis-sketch should not be viewed as final or exhaustive.

In this paper I will consider several interpretations of the fallacy of secundum quid as it is given by Aristotle in the Sophistical Refutations and argue that they do not work, one reason for which is that they all imply that the fallacy depends on language and thus fail to explain why Aristotle lists this fallacy among the fallacies not depending on language (extra dictione), amounting often to a claim that Aristotle miscategorises this fallacy. I will argue for a reading that preserves Aristotle's categorization by a quite different account of how qualifications function.

According to logical psychologism that was popular in the nineteenth century, logic was regarded as a natural ability of human psychology. Consequently, the logical competence as a realization of logic knowledge was treated as one of the innate features of human thinking. Nevertheless, within cognitive science it was experimentally proved that our thinking is not free from cognitive biases and to the same extent our reasoning is not free from logical fallacies. Hence, we are forced to consciously clear the thinking of possible distortions to follow logical norms and to realize the logical competence thereby. In the paper, it is shown that some cognitive biases are observed even at the level of cellular reactions to the environment and then at the level of animal behavior. Therefore not logic, but cognitive biases are a natural (biological) mechanism of human thinking. So, the problem of defining the logical competence arises. In this paper, there are some arguments that the logical competence has once appeared as an especial social practice and it has then been developed for a long time before the first treatises on logic.

According to Thagard, the behavior of practitioners of a field may also be used for demarcation between science and pseudoscience due to its social dimension in addition to the epistemic one. I defended the tendency of pseudoscientists to commit fallacies, and the number of fallacies they commit can be a secondary tool for demarcation problem and this tool is consistent with Thagardian approach. In this paper, I selected the astrology as the case and I revealed nine types of logical fallacies frequently committed by astrologers while introducing their field and/or defending their claims against the scientific inquiries and refutation efforts. I also argued that recognizing these fallacies may help the audience to demarcate between the scientific and the pseudoscientific arguments.

Subtite: WANTED: Real Fallacies. No Borderline Cases Need Apply

Fallacy theory is popular among skeptics, but it is in serious trouble. Every fallacy in the traditional taxonomy runs into a destructive dilemma which I call the Fallacy Fork: either fallacies hardly ever occur in real life, or they are not want fallacious.

This chapter illustrates how governmental officials use strategic communication to legitimate stands on public policy issues. Government rhetors, because of their role as decision makers and influencers over the public policy process, have power that even the leaders of multinational organizations often do not have.