No one really knows how much labour to let in

A temporary foreign worker from Mexico working at a berry farm in Mirabel, Que. Photo by Graham Hughes/The Canadian Press files

In my days as a university professor I was often involved in hiring. My department was ambitious and wanted to improve its competitive standing, so we were always keen to hire the best candidate available. That meant we ignored people’s citizenship and instead focused, like NHL general managers, on their potential — in our case, not to score goals, but to do successful research. (Likely coherence in the classroom also counted, but much less.)

We didn’t ignore Canadians. Quite the opposite: we usually went hard after good Canadians, judging they’d be more likely to accept an offer, not being put off by icy winds or high taxes. (Hiring season for new PhDs in eco