Impossible

• Proof by contradiction:
• First, let us define a list as a countable set of entries, and a leftist tendency as a leftist philosophy with a unique set of beliefs, i.e. at least one belief different from any other tendency.
• Assume that we could create a list of all leftist tendencies.
• Let A be a set of all tendencies, and L be a list of tendencies.
• assume, for contradiction, there is a function L->P, call this function f
• let t be in A. f(i) = t
• but, eventually, there will be a splitter in t that defines a new ideology, t s that changes the i th belief
• t s cannot be in the list as it now differs from f(i)
• this is a contradiction, therefore creating the list is impossible