Adolf Hitler. Opponents of immigration restrictions - myself included - often cite the examples of immigrants who make extraordinary contributions to society . For example, immigrants contribute disproportionately to major entrepreneurial and scientific innovations, such as the development of the first two successful Covid vaccines approved by the FDA. The immigrants in question probably would not have been able to make these contributions if they were confined to their countries of origin. Even if only a tiny fraction of immigrants achieve such feats, migration restrictions cumulatively forestall a substantial number of such accomplishments, thereby causing great harm, that goes beyond...