Psychology is something known as a "soft science," which is a science that studies the abstract: Behaviors, interactions, thoughts, feelings, etc. This is in opposition to "hard science" which studies the concrete, natural world. Human behavior is an intangible product of the mind. It cannot be physically studied like the natural world can, and it is susceptible to countless variables such as personality, environment, personal experiences, and so on. As a result, it is difficult to interpret and even more difficult to predict. However, human behavior can be observed, theorized, hypothesized, and experimented upon just like the physical realm. The results may be intangible and abstract, but they can give valuable insight into the human mind and be useful in practical applications where human behaviors can be reasonably predictable.
Psychology studies more than just the abstract. Neuropsychology is a branch of psychology which studies the physical brain in order to understand human behaviors. Since the physical brain can be studied, more concrete data can be used to interpret the abstract workings of the mind. In this way, Psychology should be considered a hard science; or in the very least, neuropsychology should.
[P1] Psychology studies the abstract influences on the human mind. [P2] Psychology is a soft science, but not a hard science.
Rejecting the premises
[Rejecting P1] Neuropsychology, which is a branch of psychology, studies the physical mind to understand human behaviors. [Rejecting P2] Psychology is a hard science.