Answer:
Advantages of reductionism - Reducing behaviour to simple principles can have it's benefits because it makes behaviour easier to understand and develop hypotheses to test.
Disadvantages of reductionism - Many things impact behaviour and by ignoring some factors this means a theory might not fully explain behaviour. Biological reductionism is particularly problematic as biologists are often not concerned with why or how people might behave in a certain way just what biological processes are involved.