They always deflect your challenges.

Almost every linchpin or keystone theory is also a “self‑sealing system,” that is, an assumption that cannot be disproven because it can explain away any criticism directed at it. For example, Freudian psychoanalysis includes the concept of “denial”: When patients find certain truths too painful, they may respond at first by denying them. So if an analyst develops an interpretation of a patient’s inner life that the patient rejects, the analyst may respond by explaining that the patient is in denial, not that the analyst is wrong. In that way, the concept of denial makes certain psychoanalytic interpretations a self-sealing system.

Similarly, Marxism and radical feminism can be self-sealing systems. To a Marxist, if a worker doesn’t think she is being exploited, that is because the capitalists have succeeded in creating a “false consciousness” in her. She has, in effect, been brainwashed to buy into a belief system that disables her from recognizing her own exploitation. She doesn’t feel exploited because she views her role as a worker as either the natural order of things or what she deserves, or both. Pure Marxism is thus a self-sealing system because a disagreement with its theory can be explained away as a symptom of the capitalists’ success in imposing their ideology on the masses.

To certain radical feminists, anti-feminist women are the best evidence of women’s subordination, not adversaries whose ideas merit serious reflection. Women who oppose abortion or insist that they have no place at the office have succumbed to male-dominated ideology against their own interests. Men who take advantage of women or think the status quo is the natural state for the sexes have similarly fallen victim to the prevailing culture’s bias. And every argument that chauvinistic men and anti-feminist women marshal to prove their point is simply more evidence of how successfully they’ve been indoctrinated.

As with all self-sealing systems, the fact that Marxism and radical feminism can explain away their critics does not necessarily make these linchpin theories wrong. But that feature of self-sealing systems should at least give us pause. Even if there were such as thing as a perfectly correct linchpin theory, it would appear to be a self-sealing system. Of course, a truly perfect explanation of everything in the world would indeed be able to refute its detractors! Unfortunately, there’s often no easy way to tell an accurate self-sealing system from a flawed one.