 The tree is a statement of similarity and a hypothesis that the similarity results from descent from a common language.The comparative method, a process of deduction, begins from a set of characteristics, or characters, found in the attested languages.If the entire set can be accounted for by descent from the proto-language, which must contain the proto-forms of them all, the tree, or phylogeny, is regarded as a complete explanation and by Occam's razor, is given credibility.