The problem is not making good arguments or having a good approach: The problem is access.
The Left’s intentionally imposed monopoly on discourse prevents the average liberal of even becoming aware that there is an opposing viewpoint. Only the weakest and most ill-spoken conservative notions even get presented in the liberal media, as token examples to laugh at and scorn. We at PJM (and similar sources) could have the best and most convincing and most brilliant arguments and positions ever, and it would do no good because no liberal would ever see them. This is by design.
The problem is not to come up with better ideas: The problem is how to get those ideas onto the liberal menu.
Another issue to consider: “Deprogramming” never happens in a group setting; it happens in private, individually. Peer pressure prevents people from declaring their new-found views publicly at the time of the conversion. Thus, it’s difficult to “covert” masses of people at once, and it’s basically impossible to ever see any evidence that you may have been successful. You could go to Speakers Corner and have 99 people jeering at you and throwing rotten tomatoes; but neither you nor the tomato throwers will ever notice the silent person at the back of the crowd who internalized your message and walked away a changed man.
And that’s the best we can hope for. One at a time. Silently, privately, little by little. We may already be much more successful than we realize.
As a pioneering blogger wrote a decade ago:
As the old saying has it, the left looks for heretics and the right looks for converts, and both find what they’re looking for. The effect is no doubt subliminal, but people who treat you like crap are, over time, less persuasive than people who don’t. If people on the Left are so unhappy about how many former allies are changing their views, perhaps they should examine how those allies are treated.
Or to put it another way, Krauthammer’s Law posits that “To understand the workings of American politics, you have to understand this fundamental law: Conservatives think liberals are stupid. Liberals think conservatives are evil.” The latter stance seems like a pretty potent firewall against opposing ideas.