In the domain of Choice, the Entities row identifies the most basic objects that exist in a one-agent world. Because Choice analyzes decisions made by a single, unified decision-maker under fixed conditions, the ontology must be exceptionally sharp: only the agent and the elements that structure that agent’s decision problem count as real at this level of analysis. Nothing else—no other agents, no system forces, no institutional structures—belongs to the entity set.

This section establishes the primitive building blocks of isolated optimization: the agent, its preferences, its feasible actions, its constraints, and the informational structure within which it chooses. Everything downstream in the theory—optimization rules, comparative statics, intertemporal choice—must be expressible solely in terms of these entities or compositions of them. If something requires another decision-maker or a system-level variable, it exits Choice immediately.

Entities here define what the world is made of when only one decision-maker exists.


1. Choice selects a small set of primitive objects that define its world.

The ontology of Choice consists of the minimal set of primitives needed to model a single agent’s decision problem.
These include:

No other agents exist at this scale.
No institutions exist.
No system-level variables exist.
Only these primitives and the structures built from them define the universe of Choice.

They are the “atoms” of its conceptual world.

2. Choice’s entity-set is mutually exclusive from higher domains and mutually supporting within itself.

Because the domain assumes exactly one agent, it cannot assume:

Likewise, Choice does not assume:

Its ontology is intentionally narrow and self-contained:
each entity depends only on the agent and its environment-as-parameters.
This exclusivity prevents the domain from collapsing upward or downward into other fields.

3. Choice’s ontology determines the correct level of explanation.

By defining the agent as the only active entity, Choice implicitly sets:

Everything outside this frame—strategic behavior, institutional mediation, systemic evolution—is simply not an allowable explanation.

The entity list becomes the filter that determines what explanations are valid.

4. Composite entities build upward in Choice, but only through its own rules.

Choice permits composite objects only if they are derivable from its primitives:

But it does not permit composite entities that rely on:

The only composites allowed must be internal constructions of the agent’s decision problem, not external structures.

5. Interdisciplinary fields expose joints between Choice and adjacent domains.

Hybrid zones occur precisely at the boundaries where entity sets intersect:

These interfaces exist because Choice’s ontology is cleanly defined.
Hybrid work succeeds only when entity distinctions remain intact.

6. Choice accepts formal entities only as abstract tools anchored to its primitives.

Choice relies on mathematical and logical objects—preferences, utility functions, feasible sets, operators—but treats them strictly as abstract representations of the agent’s internal decision structure.

They are not “entities” in the physical or social sense; they are formal constructs tied to the single-agent ontology.
For example:

They do not become independent objects of study as they might in higher domains or formal sciences.

7. The resulting ontology of Choice is clean, non-overlapping, and precisely bounded.

Once entities are fixed, Choice becomes an ontologically distinct field:

All downstream analysis—laws, models, methods, conclusions—must reference only these entities or compositions built exclusively from them.

Choice now has a full ontological foundation:
clean, non-redundant, non-overlapping, and structurally distinct from the domains above and below it.