It seems that one characteristic of the present Western culture is redefining anything. The unborn has now been defined as a human being who is not a person. Marriage is no longer just between a man and a woman. Homosexuality is no longer a mental disorder. With all these redefinition, it is confusing whose testimony is to be believed. My question is: is there any correct criteria for defining anything, or is it simply the case that the definition of something depends on what people thought about it?