If Donald Trump and Barack Obama agree on something, does that mean it’s true? In the case of Europe’s woeful support of its collective defense, yes: Member states need to contribute their “fair share” toward the North Atlantic Treaty Organization, a phrase both men used in speeches in European capitals. The question is what “fair share” means. Instead of measuring …

Economists, to put it mildly, are not known for their communication skills. The typical economics paper is written in a formal, stilted style, laden with phrases like ‘in the following subsection’ and ‘it has been shown that.’ Jargon flies thick and fast, interspersed with highly formalized mathematical definitions and propositions. For a non-economist to hack through the verbal jungle of …

Why so surprised, bank investors? Shares of two of the largest US lenders, JPMorgan Chase & Co. and Bank of America Corp., tumbled recently to their lowest levels in at least four months after executives said second-quarter trading revenue is poised to fall at least 10 percent from the same period a year ago. Rival Wall Street banks with large …