He was Bobby Kennedy like because in some ways one could never tell if he was a realist masquerading as an idealist or an idealist masquerading as a realist, as people always wondered about Bobby Kennedy and John Kennedy in that way.

America used to have essentially two varieties of foreign policy positions realist and idealist. But today opinions are fragmented across a broad range of positions a situation that also cries out for leadership.

Kissinger is no idealist icon. But he s always worth listening to, and never more so than with respect to the question that he has been asking for years When the next nuclear weapons catastrophe happens, as it surely will, the world will have to respond dramatically.

George W. Bush was the most recent idealist proponent of making democracy promotion the main priority for US foreign policy. Bush embraced the so called democratic peace theory, which holds that democracies not only treat their own citizens better, but also act better toward their neighbors and others.

The world has seen such a synthesis before. When, after the First World War, President Woodrow Wilson proclaimed the advent of the so called New Diplomacy, whereby secrecy and the balance of power would be replaced by open covenants and collective security, many people regarded such things as the dreams of an idealist preacher.

But recent advances in psychology and neuroscience may suggest that if we want to understand social and political behavior, or improve policies, we should be reading Hegel more than Bentham. That may sound weird, given that Hegel was an Idealist and would never have expected neuroscience a material reality independent of Geist (usually translated as Mind or Spirit) to be relevant to his inquiry.

According to this idealist view, countries that are democratic and treat their citizens with respect are more likely to treat other countries citizens with respect. The problem, of course, is that affecting the trajectories of other societies is typically a difficult, long term proposition in the meantime, there are pressing global challenges that need to be addressed, sometimes with the assistance of unsavory regimes.

Then, in 1934, resentment against growing corruption led Calles to choose an honest idealist to become president, a young man who had fought for him early in the revolution, who he thought he could control but who would help the government regain popularity. That honest revolutionary, Lázaro Cárdenas, toured the country, building his popular support, and then turned on Calles, expelling him from Mexico.

Jeffrey Sachs s new book The End of Poverty argues that with proper help from advanced countries the world could see the end of poverty as we know it in coming decades, prompting some to describe him as a starry eyed idealist. But if we take account of both the increased generosity of rich nations and the application of improved financial and insurance technology, he just might be right.

But it is a tribute to the American two party system s capacity for political integration that extremist forces remain marginalized, despite the rhetoric of the Tea Party. President Barack Obama, in particular, has been able to attract support as a liberal left idealist and as a centrist realist at the same time, which enabled him to win re election in the face of a weak economy and an even weaker labor market.