Answer :
Science is needed in the study of human development because: non empirically based opinions arise from research.
Science is required in the study of human development because research provides facts and data which will make people enabling to live their lives fully.
There are certain other reasons which make it important to study human development scientifically like the understanding of human development throughout their lifespan, makes a better understanding of the children or the off springs and the way to deal with them. The study of human development usually follows a predictable pattern so it makes a better understanding and enables to take better decisions at certain point of time.