Final answer:
Social races are a cultural construction with no real-world effects, based on arbitrary definitions and rejected by social science organizations. Previous racial categories were pseudoscientific and used to justify racism.
Step-by-step explanation:
The concept of social races is that they are a cultural construction and have no real-world effects. They are groups assumed to have a biological basis, but they are defined in a culturally arbitrary manner. The social science organizations like the American Association of Anthropologists and the American Sociological Association have taken an official position rejecting the biological explanations of race. Research suggests that race is not biologically identifiable and previous racial categories were arbitrarily assigned, based on pseudoscience, and used to justify racist practices.