Fictionalism is a methodological theory in philosophy that suggests that statements of a certain sort should not be taken to be literally true, but merely as a useful fiction. Two important strands of fictionalism are modal fictionalism (which states that possible worlds, regardless of whether they exist or not, may be a part of a useful discourse) and mathematical fictionalism, 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.

Fictionalism consists in at least the following three theses:

1. Claims made within the domain of discourse are taken to be truth-apt; that is, true or false.
2. The domain of discourse is to be interpreted at face value--not reduced to meaning something else.
3. The aim of discourse in any given domain is not truth, but some other virtue(s) (e.g., simplicity, explanatory scope).

Noun

fictionalism (countable and uncountable; plural fictionalisms)

1. (philosophy) The doctrine that certain concepts are simply convenient fictions
   • 2007, July 17, Chris John Daly, “Fictionalism and the attitudes”, Philosophical Studies, volume 139, number 3: 

     But it seems to me that modal fictionalism is also incredible: normally we do not think that there are countless theories and stories besides the ones we will ever tell, much less that they are infinitely complex and infinitely long and so that it would be humanly impossible to tell them.

• fiction
• fictional
• fictitious