Final answer:
The term for assuming all are the same and categorizing them based on simplified generalizations is 'stereotype'. These can lead to prejudice and racism, which are negative thoughts, feelings, and beliefs about an individual based on group membership.
Step-by-step explanation:
To assume all are the same and to categorize can be best described by the term stereotype. Stereotypes are oversimplified generalizations about groups of people. They can be based on various characteristics such as race, ethnicity, and gender, and they often do not take individual differences into account. For instance, saying all members of a racial group are lazy is an example of a negative stereotype. Such stereotypes can lead to or reinforce prejudice, which refers to prejudged negative thoughts and feelings about individuals based solely on their group membership. Racism is a more specific form of prejudice, which includes the belief that one race is inherently superior or inferior to other races and may involve discriminatory actions.