The term “soft science” is sometimes used to refer to branches of scientific inquiry which rely more on conjecture and qualitative analysis than rigorous adherence to the scientific method. This phrase is often used as a pejorative, differentiating it from “hard science,” with the implication that only hard science is real science. A number of fields could be considered soft science, including the social sciences, psychology, and anthropology, although in fact these fields represent a mix of soft and hard science.
In hard science, the focal point is experiments. Researchers set up experiments which can be carefully controlled and reproduced, and they use these experiments to test a hypothesis, collecting data which can be analyzed in a variety of ways to gather information about the outcome of the experiment. Hard science relies on direct observation, and prides itself on being as balanced and unbiased as possible. The goal is to get to the facts above all else.
Soft science may or may not involve experiments, depending on the field, and the experiments may be harder to control or reproduce. Psychological studies, for example, have a number of variables which cannot be controlled, making it difficult to analyze the data from such experiments, or to ask other researchers to repeat the experiment. This branch of the sciences utilizes conjecture and a more open-ended discussion, rather than sticking to clearly defined boundaries, facts, and topics, and conjectures in soft science may be unprovable with experiments and other research.
Psychology is often used as an example of soft science. Some branches of psychology certainly do tend in the soft direction, since this science involves the exploration of the human mind, consciousness, and other slippery topics. However, psychologists have also managed to stage very successful experiments to test hypotheses, and these experiments have been clearly replicable, demonstrating all the traits of hard science.
Some people suggest that the boundary between soft and hard science is largely artificial, and that the differences between the two may be exaggerated. Some scientists agree with this point of view, preferring to differentiate between good and bad science rather than hard and soft science, and pointing out that many of the alleged “hard sciences,” like physics, rely on vast leaps of logic and conjecture, especially at the higher levels. Had Einstein been limited by the confines of hard science, for example, he might never have come up with this Theory of Relativity, since the theory involved a great deal of conjecture and a scientific leap of faith when he first came up with it.