The diversity principle in the testing of arguments

According to the diversity principle of scientific reasoning, hypotheses receive greater confirmation when they are supported by diverse rather than similar sets of data. This article examines whether people reason like intuitive scientists by conforming to the diversity principle in the testing of arguments. The results of two experiments demonstrate that people do indeed conform to the diversity principle by choosing a set of diverse rather than similar premises to test the conclusion of an argument. These findings are discussed in terms of the different reasoning processes involved in argument evaluation, argument testing, and rule discovery.     

A new principle of pellet feeder design

Most current commercial devices dispense dry food pellets by moving the pellets horizontally toward a discharge point. Individual pellets, captured by perforations in a horizontal metal disk, are discharged one by one by stepwise rotation of the disk within the pellet reservoir. In our laboratory, where the average pellet discharge rate is some 20,000 pellets per week, feeders of this type produced occasional problems. Some were electronic; others involved failure always to capture a pellet in each perforation, particularly when the pellet supply was low. But the most common problem was an accumulation of pellet chips and dust under and around the perforated disk, which ultimately jammed the mechanism. Despite weekly cleaning and maintenance, troubles arose at least twice a month, prompting a search for a simpler pellet-feeder design which would be more reliable and require less maintenance. The present pellet feeder employs a vertical rather than horizontal design principle. It has been used extensively in operant conditioning applications for more than a year. More than 200,000 pellets have been reliably discharged from a single feeder without a breakdown. No maintenance, other than a weekly cleaning of the discharge tube, has been required.     

A logical expression of reasoning

A non-monotonic logic, the Logic of Plausible Reasoning (LPR), capable of coping with the demands of what we call complex reasoning, is introduced. It is argued that creative complex reasoning is the way of reasoning required in many instances of scientific thought, professional practice and common life decision taking. For managing the simultaneous consideration of multiple scenarios inherent in these activities, two new modalities, weak and strong plausibility, are introduced as part of the Logic of Plausible Deduction (LPD), a deductive logic specially designed to serve as the monotonic support for LPR. Axiomatics and semantics for LPD, together with a completeness proof, are provided. Once LPD has been given, LPR may be defined via a concept of extension over LPD. Although the construction of LPR extensions is first presented in standard style, for the sake of comparison with existing non-monotonic formalisms, alternative more elegant and intuitive ways for constructing non-monotonic LPR extensions are also given and proofs of their equivalence are presented.     

A logical calculus with descriptions

Journal of Philosophical Logic -     

A plea for logical objects

An account of validity that makes what is invalid conditional on how many individuals there are is what I call a conditional account of validity. Here I defend conditional accounts against a criticism derived from Etchemendy’s well-known criticism of the model-theoretic analysis of validity. The criticism is essentially that knowledge of the size of the universe is non-logical and so by making knowledge of the extension of validity depend on knowledge of how many individuals there are, conditional accounts fail to reflect that the former knowledge is basic, i.e., independent of knowledge derived from other sciences. Appealing to Russell’s pre-Principia logic, I defend conditional accounts against this criticism by sketching a rationale for thinking that there are infinitely many logical objects.     

A new approach to manipulation arguments

There are several argumentative strategies for advancing the thesis that moral responsibility is incompatible with causal determinism. One prominent such strategy is to argue that agents who meet compatibilist conditions for moral responsibility can nevertheless be subject to responsibility-undermining manipulation. In this paper, I argue that incompatibilists advancing manipulation arguments against compatibilism have been shouldering an unnecessarily heavy dialectical burden. Traditional manipulation arguments present cases in which manipulated agents meet all compatibilist conditions for moral responsibility, but are (allegedly) not responsible for their behavior. I argue, however, that incompatibilists can make do with the more modest (and harder to resist) claim that the manipulation in question is mitigating with respect to moral responsibility. The focus solely on whether a manipulated agent is or is not morally responsible has, I believe, masked the full force of manipulation-style arguments against compatibilism. Here, I aim to unveil their real power.     

Erotetic arguments: A preliminary analysis

The concept of erotetic argument is introduced. Two relations between sets of declarative sentences and questions are analysed; and two classes of erotetic arguments are characterized.     

A Bayesian analysis of debunking arguments in ethics

Philosophical Studies - Debunking arguments in ethics contend that our moral beliefs have dubious evolutionary, cultural, or psychological origins—hence concluding that we should doubt such...