Nobility in the age of the Psychopath

I realized the other day that there's a line of thought in David Weber's Honor Harrington series that is never coherently explicated, but it's clearly there.

We, now, live in the Age of the Psychopath. Almost all the restraints that prevented psychopaths from clawing their way into positions of authority are gone; books and magazines on the subject remind us that one out of twenty people is a psychopath-- usually above average in intelligence, unrestrained by common communal or instinctual fear or guilt about mistreating others, and in our hyperindividualized culture, plunked down straight into a mass population of ready victims. Most psychopaths aren't like those in the movies; they're not murderers, for example, because they're mostly above average in intelligence and know that's a crime they're unlikely to get away with.

One of the premises of the Manticoran system is that of entailment, the idea that there is an inherited nobility, with inherited responsibilities and rights, that cannot be transferred out of a family. And one of the follow-on premises is that the nobility, with their own house in Parliament, is a firewall against psychopaths.

If a significant amount of power in the government rests with the House of Lords, and the House of Lords is made up of men and women who inherit their positions from their progenitors, then it follows that, unlike the House of Commons, the House of Lords is made up of a population that, by now, has the same number of psychopaths as the general population.

That's not to say that psychopaths won't rise to the role of Whip, or some other leadership role within the House of Lords, but the house itself is made up mostly of neurotypicals. And their main job is to be a brake as the House of Commons barrels along, determined to make the concentration of wealth and power by means indistinguishable from sadism.