1. Complete skepticism (the notion that a belief in philosophical skepticism requires just as much justification as other beliefs);
2. Fallibilism (the view that there are no metaphysical guarantees against the need to revise a belief);
3. Antidualism about "facts" and "values";
4. That practice, properly construed, is primary in philosophy. (WL 152)

1. All ideas and perceptions concerning reality are given to our minds in terms of our own mental language.
2. Mental languages specify how objects in the world are to be constructed from our sense data.
3. Different mental languages will specify different ontologies (different objects existing in the world).
4. There is no way to perfectly translate between two different mental languages: there will always be several, consistent ways in which the terms in each language can be mapped onto the other.
5. Reality apart from our perceptions of it can be thought of as constituting a true, object language, that is, the language which specifies how things actually are.
6. There is no difference in translating between two mental languages as translating between the object language of reality and one's own mental language.
7. Therefore, just as there is no objective way of translating between two mental languages (no one-to-one mapping of terms in one to terms in the other) there is no way of objectively translating (or fitting) the true, object language of reality into our own mental language.
8. And therefore, there are many ontologies (possibly an infinite number) that can be consistently held to represent reality.

1. Languages are used to obtain certain ends within communities.
2. Each language has its own set of rules and objects to which it refers.
3. Just as board games have rules guiding what moves may be made so do languages within communities where the moves to be made within a language game are the types of objects that may be talked about intelligibly.
4. Two people participating in two different language-games cannot be said to communicate in any relevant way.

(1) семантический холизм Ч.С. Пирса, (2) теоретико-познавательный антифундаментализм, (3) натурализм, (4) антидуализм по отношению к фактам и ценностям и (5) практическая ориентация философского мышления.