Final answer:
Dr. Downey made two extended arguments about why stratification is important to study. The Davis-Moore thesis suggests that stratification promotes excellence and productivity, while Tumin's argument highlights the potential inequalities in opportunity and reward created by social stratification.
Step-by-step explanation:
Dr. Downey made at least two extended arguments about why stratification is important to study. One argument is the Davis-Moore thesis, which states that social stratification is necessary to promote excellence, productivity, and efficiency. According to this thesis, stratification gives people something to strive for and allows everyone to benefit to a certain extent. Another argument is presented by Melvin Tumin, who questioned the degree of importance assigned to different jobs. Tumin argued that social stratification can prevent qualified individuals from pursuing certain roles, leading to inequalities in opportunity and reward.