People like Hertzberg begin from what is, for them, an unassailable proposition: liberalism is right because it is right and so it can never be wrong. And what happens when, by any objective standard, liberal policies fail? The problem is, they weren’t sufficiently liberal.
There are certain advantages to this approach. Those whose minds are obdurate and canonical –regardless of the philosophy they hold — don’t need to grapple with inconvenient facts. They have a reflexive response to every set of facts that challenges their worldview: ignore the facts. This doesn’t help one ascertain the truth. But it does avoid the hard work of facing up to the false assumptions on which their intellectual structure rests. Call it the comforting life of an ideological fanatic.