In philosophy, a theory of everything or ToE is an ultimate, all-encompassing explanation or description of nature or reality.[1][2][3] Adopting the term from physics, where the search for a theory of everything is ongoing, philosophers have discussed the viability of the concept and analyzed its properties and implications.[1][2][3] Among the questions to be addressed by a philosophical theory of everything are: "Why is reality understandable?" "Why are the laws of nature as they are?" "Why is there anything at all?"[1]