Almost at the same time as he adopts the ramified theory of types, Russell abandons propositions. From about 1908 until 1918, although Russell retains the idea that there are true propositions, he denies that there are false ones. When we think about something that is false, say, Zermela is a cat, we are not thinking about a false proposition, but rather the objects of our thought are just Zermela and the property of being a cat. It might seem odd to have a hierarchy especially designed to stratify the propositions and then claim that there are no propositions. Some interpreters, however, have claimed that Russell's denial of the existence of propositions should not be taken seriously and that there are very good reasons to read Principia as being largely a theory of propositions (see Church 1984).