Rules for Reasoning from Knowledge and Lack of Knowledge

In this paper, the traditional view that argumentum ad ignorantiam is a logical fallacy is challenged, and lessons are drawn on how to model inferences drawn from knowledge in combination with ones drawn from lack of knowledge. Five defeasible rules for evaluating knowledge-based arguments that apply to inferences drawn under conditions of lack of knowledge are formulated. They are the veridicality rule, the consistency of knowledge rule, the closure of knowledge rule, the rule of refutation and the rule for argument from ignorance. The basic thesis of the paper is that knowledge-based arguments, including the argument from ignorance, need to be evaluated by criteria for epistemic closure and other evidential rules that are pragmatic in nature, that need to be formulated and applied differently at different stages of an investigation or discussion. The paper helps us to understand practical criteria that should be used to evaluate all arguments based on knowledge and/or ignorance.

A Proof System for Classical Logic

An operation on inferential rules, called H-operation, is used to minimize the axiom basis for classical logic.     

JEAB Research Over Time: Species Used,Experimental Designs,Statistical Analyses,and Sex of Subjects

We examined the species used as subjects in every article published in the Journal of the Experimental Analysis of Behavior (JEAB) from 1958 through 2013. We also determined the sex of subjects in every article with human subjects (N = 524) and in an equal number of randomly selected articles with nonhuman subjects, as well as the general type of experimental designs used. Finally, the percentage of articles reporting an inferential statistic was determined at 5-year intervals. In all, 35,317 subjects were studied in 3,084 articles; pigeons ranked first and humans second in number used. Within-subject experimental designs were more popular than between-subjects designs regardless of whether human or nonhuman subjects were studied but were used in a higher percentage of articles with nonhumans (75.4 %) than in articles with humans (68.2 %). The percentage of articles reporting an inferential statistic has increased over time, and more than half of the articles published in 2005 and 2010 reported one. Researchers who publish in JEAB frequently depart from Skinner’s preferred research strategy, but it is not clear whether such departures are harmful. Finally, the sex of subjects was not reported in a sizable percentage of articles with both human and nonhuman subjects. This is an unfortunate oversight.     

On the minimal relative motion principle—lateral displacement of a contracting bar

Xausa, Beghi, and Zanforlin (J. Math. Psychol. 45(4) (2001) 635) provide an account of perceptual organization based on their ‘minimal relative motion’ principle. They claim that this principle can account for the percept generated by a contracting bar that is simultaneously translating laterally. We critique the mathematical analysis provided in the aforementioned paper. We conclude that the ‘minimal relative motion’ principle, in the form presented, cannot adequately explain the percept reported by observers.     

Cognitive bias modification for inferential style

In this study, we developed a cognitive bias modification procedure that targets inferential style, and tested its effect on hope, mood, and self-esteem. Participants were randomly assigned to training conditions intended to encourage either a negative or a positive inferential style. Participants’ inferences for their failure on a cognitive challenge were congruent with their training condition. Moreover, compared to participants in the positive training condition, those in the negative condition reported less hope and exhibited lower mood and self-esteem following the failure. Finally, the training affected mood and self-esteem indirectly via its effect on participants’ inferences for their failure. These findings provide support for the causal role of inferential style in depressed affect.     

Problems in Psychiatric Genetic Research: A Reply to Faraone and Biederman

This article examines evidence cited in favor of the operation of genetic factors in attention-deficit hyperactivity disorder (ADHD). Like other psychiatric conditions, a belief in the genetic basis of ADHD is derived from the results of family, twin, and adoption studies. Because family studies are widely believed to be confounded by environmental factors, primary emphasis is placed on twin and adoption studies. ADHD twin studies depend on the validity of the equal environment assumption (EEA), which holds that the environments of identical (MZ) and fraternal (DZ) twins are the same. Here it is argued that however the EEA is defined, it cannot be accepted. Therefore, the greater similarity or concordance of MZ twins when compared to DZ twins is plausibly explained by environmental factors. Adoption studies constitute a third method for investigating the role of genetic factors in ADHD. It is argued that these studies are greatly flawed by factors including non blinded diagnoses and the failure to study the biological relatives of adoptees. After an examination of the total weight of evidence in favor of a genetic basis or predisposition for ADHD, it is concluded that a role for genetic factors is not supported and that future research should be directed toward psychosocial causes