The twentieth century saw confidence in racial categories collapse into doubt

Evidence

The twentieth century started confident about the use of race to designate certain kinds of group; it ended very doubtful whether any relations can properly be named racial relations, but from discussion of the difficulties much has been learned. — David Theo Goldberg, John Solomos, A Companion to Racial and Ethnic Studies, 684

Categorization

• DEFINE: Distinguishes the eventual ‘race relations’ problematic from the earlier confident use of race as a group designator.