Scientific materialism is often synonymous with, and has typically been described as being, a reductive materialism. In the early 21st century, Paul and Patricia Churchland advocated a radically contrasting position (at least, in regards to certain hypotheses): eliminative materialism. Eliminative materialism holds that some mental phenomena simply do not exist at all, and that talk of those mental phenomena reflects a totally spurious "folk psychology" and introspection illusion. A materialist of this variety might believe that a concept like "belief" simply has no basis in fact (e.g. the way folk science speaks of demon-caused illnesses).