Who's more generous?

The hot topic of the moment in the philanthropic media (including blogs) is a new book by an economist named Arthur Brooks, entitled "Who Really Cares: America's Charity Divide". His thesis, based on a variety of survey data, is actually three-fold (and to some degree overlapping):

(a) religious households both liberal and conservative give more to charity than secular households do, even without counting giving to their churches;
(b) politically-conservative people give more to charity than do politically-liberal folks; and
(c) the wealthy and the working poor give about the same fractions of their income to charity, while the middle class gives much less.

So to sum up (in my words not his): "middle-class secular people who usually vote Democratic are stingy hypocrites". That would be, um...me, and most of my friends and family, and at least 75% of my colleagues in the non-profit sector. No let's be honest, more like 90%. And a similar fraction of my former colleagues in newspaper journalism.

Coverage of the book, and of Brooks' various recent op-ed pieces promoting it, has centered on whichever of those arguments causes the most outrage with the particular writer. I did get into a brief online debate that's tangentially about this, over at White Courtesy Telephone, but before saying anything further about Brooks' facts I'll read the thing. All I've done thus far is to confirm at a surface level that at least a couple of the surveys that Brooks cite do support at least some of his claims, and locate an unrelated survey that supports at least one of his points. More than that will have to await reading the book and checking its listed sources.