As in any social science, in comparative education, the issue of the links between academics and the political sphere is lively debated; should we be “pure” scientists or experts? The papers maintains that, in spite of the traps existing surveys such as PISA entail, we cannot neglect the data they provide, even if those “facts” are of course socially constructed and so should be used cautiously. That does not mean that we should limit our investigations to the issues they bring on the agenda. In any case, they exist and we may maintain that we are the most competent to assess both their usefulness and their limits. Moreover, not only the comparative empirical work they allow is worthwhile in itself and socially relevant, but it may foster also theoretical advances. In any case, that would be irresponsible not to take our place, on that basis but also integrating our wider knowledge of the field, in the political debates on education issues.