The proposition that trade restrictions reduce economic welfare is certainly not generally valid, and it is violated when certain conditions – such as externalities or increasing returns to scale – are present. Moreover, it requires that economists make value judgments on distributional effects, which are better left to the electorate itself.
考虑我在上文中列举的存在广泛共识的领域。贸易限制降低经济福利的意见显然不是放之四海而皆准的，当出现某些特定状况时（如外部性和规模报酬递增），它就不成立。此外，经济学家还需要做出分配效应的价值判断，而这留给选民本身来做更加合适。