The purpose of the estates of decedents law is to simplify the administration of estates, to reduce the expenses of administration, to clarify the law governing estates of decedents, and to eliminate any provisions of prior law which are archaic, often meaningless under modern procedure and no longer useful. This article shall be liberally construed and applied to promote its underlying purpose. Unless otherwise expressly provided, whenever the estates of decedents law states that a fact is presumed, the presumption is rebuttable.