Effects of daylight-saving time changes on stock market volatility: a comment

In a recent article in this journal, Berument, Dogan, and Onar (2010) challenged the existence of the previously documented daylight-saving effect. Kamstra, Kramer, and Levi's original finding (2000) was that average stock market returns on Mondays following time changes are economically and statistically significantly lower than typical Monday returns. Kamstra, et al. hypothesized that the effect may arise due to heightened anxiety or risk aversion on the part of market participants after they experience a 1-hr. disruption in their sleep habits, in accordance with prior findings in the psychology literature linking sleep desynchronosis with anxiety. Berument, et al. replicated the original findings using ordinary least squares estimation, but when they modeled the mean of returns using a method prone to producing biased estimates, they obtained puzzling results. The analysis here, based on standard, unbiased modeling techniques, shows that the daylight-saving effect remains intact in the U.S.     

Sleeping Beauty meets Monday

The Sleeping Beauty problem—first presented by A. Elga in a philosophical context—has captured much attention. The problem, we contend, is more aptly regarded as a paradox: apparently, there are cases where one ought to change one’s credence in an event’s taking place even though one gains no new information or evidence, or alternatively, one ought to have a credence other than 1/2 in the outcome of a future coin toss even though one knows that the coin is fair. In this paper we argue for two claims. First, that Sleeping Beauty does gain potentially new relevant information upon waking up on Monday. Second, his credence shift is warranted provided it accords with a calculation that is a result of conditionalization on the relevant information: “this day is an experiment waking day” (a day within the experiment on which one is woken up). Since Sleeping Beauty knows what days d could refer to, he can calculate the probability that the referred to waking day is a Monday or a Tuesday providing an adequate resolution of the paradox.     

Dogmatism repuzzled

Harman and Lewis credit Kripke with having formulated a puzzle that seems to show that knowledge entails dogmatism. The puzzle is widely regarded as having been solved. In this paper we argue that this standard solution, in its various versions, addresses only a limited aspect of the puzzle and holds no promise of fully resolving it. Analyzing this failure and the proper rendering of the puzzle, it is suggested that it poses a significant challenge for the defense of epistemic closure.     

A growth mindset intervention to improve mental health in adolescents during COVID-19

COVID-19 poses a considerable threat to adolescent mental health. We investigated depression rates in teens from pre to post-COVID. We also explored if leveraging a growth mindset intervention (“Healthy Minds”) could improve adolescent mental health outcomes during the pandemic, especially for adolescents experiencing the most distress. In Study 1, we recruited youth from schools in a rural southern community (N = 239) and used a pre-post design. In Study 2, we recruited an online sample (N = 833) and used a longitudinal randomized control trial design to test the effectiveness of Healthy Minds. Across both studies, there is evidence of higher rates of depression in youth during COVID-19, relative to pre-pandemic numbers. In Study 1, the intervention effectively changed psychological and behavioral processes related to mental health, especially for adolescents experiencing greater COVID-19 stress. However, in Study 2, the intervention failed to impact depression rates or symptoms at follow-up.     

What Does the Narcissistic Personality Inventory Measure Across the Total Score Continuum?

The Narcissistic Personality Inventory (NPI) is the most widely used measure of narcissism in the social-personality psychology literature. It contains 40 items that tap into a variety of traits that theoretically comprise narcissism, such as feelings of superiority and willingness to exploit others. Most researchers focus on the total score produced by the NPI and may logically assume that increments in total NPI score correspond with similar increments in underlying narcissism traits. However, research presented in this article suggests that the traits measured by the NPI do not increment at the same rate. Traits reflecting intrapersonally healthy qualities (e.g., leadership, superiority) increment most rapidly within the lower portions of the NPI total score continuum, whereas traits reflecting interpersonally harmful qualities (e.g., entitlement, exploitativeness) increment most rapidly within the upper portions of the NPI continuum. These differences have implications for the meaning of scores on the NPI and how they correlate with other variables. For example, we demonstrate that lower NPI scores best predict self-esteem and higher NPI scores best predict psychopathy.     

Two notions of epistemic validity

How to accept a conditional? F. P. Ramsey proposed the following test in (Ramsey 1990). (RT) ‘If A, then B’ must be accepted with respect to the current epistemic state iff the minimal hypothetical change of it needed to accept A also requires accepting B. In this article we propose a formulation of (RT), which unlike some of its predecessors, is compatible with our best theory of belief revision, the so-called AGM theory (see (Gärdenfors 1988), chapters 1–5 for a survey). The new test, which, we claim, encodes some of the crucial insights defended by F. P. Ramsey in (Ramsey 1990), is used to study the conditionals epistemically validated by the AGM postulates. Our notion of validity (PV) is compared with the notion of negative validity (NV) used by Gärdenfors in (Gärdenfors 1988). It is observed that the notions of PV and NV will in general differ and that when these differences arise it is the notion of PV that is preferable. Finally we compare our formulation of the Ramsey test with a previous formulation offered by Gärdenfors (GRT). We show that any attempt to interpret (GRT) as delivering acceptance conditions for Ramsey's conditionals is doomed to failure.     

Begging what is at issue in the argument

This paper objects to treating begging the question as circular reasoning. It argues that what is at issue in the argument is not to be confused with the claim or position that the arguer is adopting, and that logicians from Aristotle on give the wrong definition and have difficulty making sense of the fallacy because they try to define it in terms of how an argument is defined by logical theory - as a sequence consisting of premises followed by a conclusion. That the problematic about begging the question depends on treating an argument as a context-less sequence of statements seems to be anticipated by the pragma-dialectical approach. The paper offers a critique of this dialogical approach, as exemplified by Douglas Walton in his recent book on begging the question, on the grounds that it raises more problems than it solves. It concludes with the suggestion that what is really at issue in discussions of begging the question is the need for a theory of fallacy.