Always know a counter to any hold you try against your opponent.

Perhaps one may best express this by saying that concepts refer to occurrential elements of occurrential structure, while propositions refer to occurrential structures of occurrential elements.

[M]y uncle Toby […] treated himſelf with a handſome ſentry-box, to ſtand at the corner of the bowling-green, betwixt which point and the foot of the glacis, there was left a little kind of eſplanade for him and the corporal to confer and hold councils of war upon. / —The ſentry-box was in caſe of rain.

Given those two points, it comes as no surprise that Miller declined to characterize permanent incorrigibility as such an eligibility criterion.