This eighteenth chapter continues to consider ideologically motivated dissent, here specifically focusing on crises that more acutely threaten to sunder constitutional constraints and destabilize the state. We take pains to consider the function of political ideology in determining these crises, which, of course, also often interact with nonideological group interests. Multilevel selection theory is particularly helpful in this process because it is fundamentally a theory about group dynamics, explaining when and why groups form and fight. Thus, ideological determinants and group determinants can be accommodated within this multilevel selectionist framework. Even strong third-party movements and populist realignments generally garnered at least some energy from nonviolent conflicts between the major political parties; and so it should be no surprise that truly revolutionary events only come from the combination of ideology and faction. Thus, again, we see the interaction of what we have called the two sides of the political, only one of which is purely ideological. In illustration, at this chapter’s end, we briefly review representative historical events wherein ideological and sectional fault lines converge.