They had cliche answers but only to their self-created straw-men. To exaggerate only slightly, they had never talked to anyone who really believed, and had thought deeply about, views drastically different from their own. As a result, when they heard real arguments instead of caricatures, they had no answers, only amazement that such views could be expressed by someone who had the external characteristics of being a member of the intellectual community, and that such views could be defended with apparent cogency. Never have I been more impressed with the advice I once received: “You cannot be sure that you are right unless you understand the arguments against your views better than your opponents do.”
On the error of failing to appreciate your opponents’ three-dimensionality:
Source: Milton Friedman, “Schools at Chicago,” from The Indispensable Milton Friedman
H/T David Henderson at EconLog
Note: The final sentence of the passage, as presented by Henderson, is missing closing quotation marks. I have added them.
Of course, even in this case, you often cannot be very sure.