I personally believe that psychology should not be considered a science. Although psychology might sometimes be connected to neuroscience (study of the brain), psychology focuses on why a person or a group of people behave a certain way. Here is one example: lets say you are studying how a person reacts with friends, neuroscience can tell you which hormones are creating what emotions while talking with the person. Psychology on the other hand can explain the way the person speaks, hand gestures, their posture, and what that states about the state of the person right now. So to go back to the question I think psychology must be a social science rather than a science because it focuses more on the human person than the brain itself.