Fictionalism is the view in philosophy according to which statements that appear to be descriptions of the world should not be construed as such, but should instead be understood as cases of "make believe", of pretending to treat something as literally true (a "useful fiction"). Two important strands of fictionalism are modal fictionalism developed by Gideon Rosen, which states that possible worlds, regardless of whether they exist or not, may be a part of a useful discourse, and mathematical fictionalism advocated by Hartry Field, which states that talk of numbers and other mathematical objects is nothing more than a convenience for doing science. Also in meta-ethics, there is an equivalent position called moral fictionalism (championed by Richard Joyce). Many modern versions of fictionalism are influenced by the work of Kendall Walton in aesthetics.
Fictionalism consists in at least the following three theses: