Obviously we are required to carry passports when we go to France and I always do.
It is interesting though to note the differing levels of enthusiasm for checking passports in different French Airports. I have been to Le Touquet loads of times and can't remember ever having been asked to show my passport. In Deauvile though it is markedly different. They always want to see everyone's passports and as I recall, on one occasion wanted to see my pilots licence!