I am not saying that liberalism and conservatism today are not based in concrete beliefs. What I am arguing is that the concrete beliefs they are based in today are not all the same concrete beliefs the ideologies were based in 30 years ago, or 70 years ago.
For example, there are those that make the claim that if a "true conservative" were to run, that it would awaken the masses and they would all vote for them. (Liberals said the same thing when they were out of power)
In my opinion the problem with that argument is that politicians largely reflect the beliefs of their base they are trying to appeal to. Thus, if the base "modern conservative adherents" really wanted a "true conservative" in the same vein as Barry Goldwater, then Ron Paul would have had the Republican Nomination. So for all practical purposes, conservatism today is different than what it was in 1964.