Comment on "Some novel delta-function identities"

We show that a form for the second partial derivative of $1/r$ proposed by Frahm and subsequently used by other workers applies only when averaged over smooth functions. We use dyadic notation to derive a more general form without that restriction.Comment: 4 page Comment on an AJP paper. The second version modifies the discussion and corrects some misprints. This version will appear in AJP

Comment on Octet Baryon Magnetic Moments in the Chiral Quark Model with Configuration Mixing

The importance of exchange currents, and of conserving isotopic spin at both the quark and baryon levels in application of the chiral quark model to any calculation of baryon magnetic moments is emphasized.Comment: 5 pages, Latex fil

Pascal’s wager and the origins of decision theory: decision-making by real decision-makers

Pascal’s Wager does not exist in a Platonic world of possible gods, abstract probabilities and arbitrary payoffs. Real decision-makers, such as Pascal’s “man of the world” of 1660, face a range of religious options they take to be serious, with fixed probabilities grounded in their evidence, and with utilities that are fixed quantities in actual minds. The many ingenious objections to the Wager dreamed up by philosophers do not apply in such a real decision matrix. In the situation Pascal addresses, the Wager is a good bet. In the situation of a modern Western intellectual, the reasoning of the Wager is still powerful, though the range of options and the actions indicated are not the same as in Pascal’s day

Feature selection methods for solving the reference class problem

Probabilistic inference from frequencies, such as "Most Quakers are pacifists; Nixon is a Quaker, so probably Nixon is a pacifist" suffer from the problem that an individual is typically a member of many "reference classes" (such as Quakers, Republicans, Californians, etc) in which the frequency of the target attribute varies. How to choose the best class or combine the information? The article argues that the problem can be solved by the feature selection methods used in contemporary Big Data science: the correct reference class is that determined by the features relevant to the target, and relevance is measured by correlation (that is, a feature is relevant if it makes a difference to the frequency of the target)

What is the force on a magnetic dipole?

We show that attempts to modify the force on a magnetic dipole by introducing either hidden momentum or internal forces are not correct. The standard textbook result {\bf F=\nabla(\bmu\cdot B)} is correct even in the presence of time dependent electromagnetic fields. Using this expression for the force, overall momentum (the sum of mechanical and electromagnetic momentum) is conserved in changing electromagnetic fields.Comment: This version presents a more compelling argument that the textbook equation for the force on a magnetic dipole is correct, and is needed to preserve overall momentum conservatio

Science by Conceptual Analysis: The Genius of the Late Scholastics

The late scholastics, from the fourteenth to the seventeenth centuries, contributed to many fields of knowledge other than philosophy. They developed a method of conceptual analysis that was very productive in those disciplines in which theory is relatively more important than empirical results. That includes mathematics, where the scholastics developed the analysis of continuous motion, which fed into the calculus, and the theory of risk and probability. The method came to the fore especially in the social sciences. In legal theory they developed, for example, the ethical analyses of the conditions of validity of contracts, and natural rights theory. In political theory, they introduced constitutionalism and the thought experiment of a “state of nature”. Their contributions to economics included concepts still regarded as basic, such as demand, capital, labour, and scarcity. Faculty psychology and semiotics are other areas of significance. In such disciplines, later developments rely crucially on scholastic concepts and vocabulary

I was a nigger, still : Black and White Bodies in the Gay Art of the Twentieth Century

“It’s amazing to me that even the rampant homophobia in the South doesn’t put a dent in the sense of racial privilege presumed by the white gay men who patronize this clear example of racism and misogyny disguised as entertainment.” Lecia Brooks, the education director for the Civil Rights Memorial Center in Montgomery, Alabama, gave this statement to Rolling Stone magazine in 2007 to explain her protests against comedian Charles Knipp, known on stage as Shirley Q. Liquor. While Knipp’s jokes are racist, the major issue with his performances, as Brooks tells us, is his use of blackface minstrelsy as his act. Knipp, a white gay man, dons a large muumuu and masquerades as “a welfare mother with nineteen kids who guzzles malt liquor, drives a Caddy and says in an ‘ignunt’ Gulf Coast black dialect, ‘I’m gonna burn me up some chitlins and put some ketchup on there and aks [sic] Jesus to forgive my sins.’