Hard science and soft science are two categories of knowledge. Hard science is based on facts, which can be tested and proven, while soft science deals more with opinions, feelings, and beliefs. Hard science answers questions using things like experiments, observation, and equations. For example, hard science looks at things like the chemistry of a material or the speed of a river. Soft science is more about understanding behaviors and trends, and using research and theory to explore why things happen and how people think and feel. For example, soft science looks at things like the psychology of how people interact or the economics of how people make decisions.