I am spending a few days in the US (leisure plus an academic conference). When I arrived at the Boston airport a few days ago, just after leaving the aircraft we were stuck in a very slow line that ended in the immigration interrogation. Above the line there was a TV screen with the CNN on, precisely at the moment in which Donald Trump was giving a speech about "securing our borders." At that moment, it seemed to me difficult to secure the borders even better than they are. Even if Trump were to win the election, the system of checks and balances, I believe, would make it very difficult to introduce dramatic changes in a system that is relatively strict already in my view. More than the immediate policy concerns, my worry is the deterioration of political discourse and social trust that politicians like Trust implie. His probability of winning the election according to the best political statisticians is now around 22%. If the election was today, he would not win. But incorporate to the statistical model a couple of public relations tricks and a big terror attack and the probability can easily jump, in a very volatile political atmosphere. Before the party conventions in July, the probability was close to 50%. Trump is just one chain in the global exchange program of national-populism. He was visited recently by Nigel Farage and by the leader of the Italian Northern League. Rumours of Vladimir Putin supporting Donald Trump are consistent with financial links between the Russian leader and some Trump aides, as well as by statements of the American tycoon praising Putin. The main message of all these populist leaders is that "good fences make good neighbours." The policy details are scarce and usually inconvenient to them: "I will fix this and that; we will take back control"... It is not easy to see how all this wave is going to be stopped. As Louis Putterman (someone I expect to meet at the Conference I am attending this week-end) says in "The Good, The Bad and the Economy", what is wanted is this: "idealists who are not satisfied with easy answers."