Given the axiom that social reality consists of individuals and their interactions, and the conjecture that the interesting way individuals interact is through choice, this paper explicates three postulates in four stages: 1) choices are made up of ‘entrained’ sub-choices: thoughts and acts that must be made for the pursuit of another goal; 2) a sub-choice ‘entrained’ in all other choices is a choice for ‘predictability’: a quasi-Bayesian assessment whereby the greater an option’s predictability, the more likely it is to be chosen; 3) it is axiomatic that decisions should always be informed by as many truths and as few falsehoods as possible; true ‘is’ statements can only result in more fulfilling ‘ought’ statements; 4) 1 and 2, and their implications, constitute ‘is’s of sociodynamics, generating a moral and ethical ‘ought’ which I will call ‘Political Existentialism’, a stance that should inform ways in which we organize and run our societies to allow the pursuit of Eudaimonia. Both concepts point to a sociological ‘constant’: if every choice entrains predictability and predictability is a measurable variable, then each choice can be related to every other choice in a measurable way; because choice is the way in which individuals consciously interact with their environments and one another, predictability can be used as a ‘common ground’ to measure and compare cases of choice-based sociodynamics.

This essay uses an example of Margaret Archer’s morphogenetic approach to sociodynamics to explore the explanatory gap indicated in the following propositions: 1. Individuals act and interact in variable ways from constantly shifting states-of-affairs in pursuit of variable and inconsistent interests; 2. Groups are made-up of individuals and their actions/interactions; 3. The vast majority of groups, current and historic, are stable. It contends that individuals’ choices resolve the problem: the analytical centrality of (neo-Bayesian) predictability to every choice no matter the context bridges the explanatory gap between individual actions and the large-scale sociological phenomena of social stability; in the same way, the analytical centrality of stability to groups and group structures allows us to identify the predictable paths of agency. This analytical dualism is used to identify the mutual morphogenesis of both sociodynamic ‘poles’ in the example…individual and collective, ‘micro’ and ‘macro’, agent and structure-culture, in a way applicable to a wide range of rigorous sociological inquiry.