News
Successful PhD Defence Posthumus alumnus Joris Kok
On 18 September 2025, Posthumus alumnus Joris Kok succesfully defended the thesis ‘Social Mobility and Integration of Amsterdam Jews: The Ethnic Niche of the Diamond Industry, 1850-1940’ at Leiden University. Supervisors were Professor Leo Lucassen and Professor Karin Hofmeester (both IISH).
In his dissertation, Joris studies the remarkable social mobility and varied integration patterns of Jews in pre-war Amsterdam, with a particular focus on Jewish diamond workers, who formed the community’s occupational and cultural core. Drawing on uniquely detailed life-course data and a comparative perspective, it demonstrates that Jews, on average, advanced in occupational status and educational attainment faster than non-Jews, surpassing them by the early twentieth century. This upward trajectory was especially striking among diamond workers, whose high wages, strong labour organisation through the founding of the first modern union in the Netherlands, and commitment to education created novel opportunities for men and women alike. The study is the first to examine Dutch-Jewish workers’ social mobility across multiple life domains—work, marriage, residence, and education—within a comparative perspective that includes Gentile counterparts. It highlights, in particular, the exceptional intergenerational gains achieved by Jewish families connected to the diamond industry. Additionally, it demonstrates that upward social mobility and integration did not necessarily coincide and sometimes diverged: despite their increasing social status, Jewish diamond workers were considerably less likely to marry non-Jewish partners or disaffiliate religiously.
The N.W. Posthumus Institute congratulates Joris with this achievement!
