Ideas cannot be outdated by definition.
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I think you'll find that they can. Ideas become obsolete all the time (except in the very basic sense of still being valuable to historians, both professional and amateur.) You don't hear much about phlogiston theory these days, nor ptolemaic astonomy. You also don't hear much about the finer points of shoeing a horse, or (for a more professional example) positioning data on your hard disk to be read in the lowest average amount of spins. Divine right of kings is all but forgotten in western countries, even ones that have kings. (Fascism, admittedly, seems to be making a comeback, but that is the exception that proves the rule - these ideas are not supposed to become relevant again.)