Troy Cross

Humean supervenience, at least in its familiar Lewisian guise, harbors an internal inconsistency. Suppose that: (1) fundamental properties are categorical; (2) fundamental properties endow objects with different dispositions in different possible worlds; and (3) properties are individuated by sets of their possible instances. This chapter demonstrates that if (2) is true, then every fundamental property necessarily correlates with a unique disposition. Therefore, by (3), every fundamental property is identical to a disposition, contrary to (1). This inconsistency can be resolved only by acknowledging the dispositionality of fundamental properties, abandoning realism about dispositions, or allowing for the hyperintensional individuation of properties.

RationaleThere are growing concerns over the occurrence of adverse physiologic events occurring in pilots during operation of United States Air Force and Navy high-performance aircraft. We hypothesize that a heightened inspiratory work of breathing experienced by jet pilots by virtue of the on-board life support system may constitute a “distraction stimulus” consequent to an increased sensation of respiratory muscle effort. As such, the purpose of this study was to determine whether increasing inspiratory muscle effort adversely impacts on attentional performance.MethodsTwelve, healthy participants were recruited for this study. Participants completed six repetitions of a modified Masked Conjunctive Continuous Performance Task protocol while breathing against four different inspiratory threshold loads to assess median reaction times. A computer-controlled threshold loading device was used to set the inspiratory threshold loads. Repeated measures analysis of variances were performed to examine: the efficacy of the threshold loading device to impose significantly higher loading at each loading condition; the effects of loading condition on respiratory muscle effort sensation; and the influence of hypercapnia on MCCPT scores during inspiratory threshold loading. Generalized additive mixed effects models were used to examine the potential non-linear effects of respiratory muscular effort sensation, device loading, and hypercapnia, on MCCPT scores during inspiratory threshold loading.ResultsInspiratory threshold loading significantly augmented inspiratory effort sensation and the inspiratory pressure-time product. Our analyses also revealed that median hit RT was positively associated with inspiratory effort sensation during inspiratory loading trials.ConclusionThe findings of this work suggest that it was not increasing inspiratory muscle effort per se, but rather participant’s subjective perception of inspiratory “load” that impacts negatively on attentional performance; i.e., as the degree of inspiratory effort sensation increased, sotoo did median hit RT. As such, it is reasonable to suggest that minimizing inspiratory effort sensation during high-performance flight operations may prove useful in reducing pilot RTs during complex behavioral tasks.

Are fundamental properties dispositional, like fragility, or categorical, like triangularity? Much hangs on this question, including the modal status of the laws of nature and the relation between conceivability and possibility. I first map the contours of the issue, exploring the space of possible positions and outlining the common assumptions. Next I evaluate the existing arguments, none of which I find ultimately persuasive. Finally, I introduce a novel position, macro-Humeanism, which renders fundamental properties categorical, yet attempts to capture the intuitions driving philosophers to embrace fundamental dispositions as well.

Attempts to capture the distinction between categorical and dispositional states in terms of more primitive modal notions – subjunctive conditionals, causal roles, or combinatorial principles – are bound to fail. Such failure is ensured by a deep symmetry in the ways dispositional and categorical states alike carry modal import. But the categorical/dispositional distinction should not be abandoned; it underpins important metaphysical disputes. Rather, it should be taken as a primitive, after which the doomed attempts at reductive explanation can be transformed into circular but interesting accounts.