[2] Many intellectuals turned to Herbert Spencer's social Darwinism and blamed Poland's erstwhile Romantic ("Messianist") philosophy for the insurrectionary disasters.
[11][12][13][14][15] This was also the period in which Polish nationalism, which was previously common to both left-wing and right-wing political platforms, became more redefined as being limited to the right-wing,[16] with the emergence of the politician Roman Dmowski (1864-1939), who renamed Liga Polska (the Polish League) as Liga Narodowa (the National League) in 1893.
The post-World War II human migrations from 1945, with the resultant demographic and territorial changes of Poland that drastically reduced the number of ethnic minorities in Poland, also played a major role in the creation of the modern Polish state and nationality.
[18][27] In communist Poland (1945-1989), the regime adopted, modified and used for its official ideology and propaganda some of the nationalist concepts developed by Dmowski.
As Dmowski's National Democrats strongly believed in a "national" (ethnically homogeneous) state, even if this criterion necessitated a reduced territory, their territorial and ethnic ideas were accepted and practically implemented by the Polish communists, acting with Joseph Stalin's permission.
Stalin himself in 1944-45 conferenced with and was influenced by a leading National Democrat Stanisław Grabski, coauthor of the planned border and population shifts and an embodiment of the nationalist-communist collusion.
[28] Polish nationalism, together with pro-American liberalism, played an important part in the development of Solidarity movement in the 1980s.