In Interaction, classifications play a far more explicit and central role than in Choice. Whereas Choice focuses on individual allocation over objects, Interaction concerns structured relationships among multiple agents, where outcomes depend on how actions intersect. As a result, interaction economics relies on formal, named classification systems that partition social and economic arrangements into distinct kinds, each governed by different rules, equilibria, and institutional constraints. These classifications define the grammar of interaction—the types of strategic situations, market forms, and institutional settings within which economic behavior unfolds.
Hierarchies and Multi-Level Categories
Interaction classifications are commonly hierarchical, organizing broad interaction environments into progressively more specific forms. At the highest level, interaction settings are often divided into markets, games, and institutions, which then subdivide into specialized types. For example, markets may be classified into competitive and non-competitive forms, which further subdivide into monopolies, oligopolies, and differentiated markets. Similarly, strategic interactions are organized into broad classes of games, which then branch into subclasses based on move structure, information, or payoff relationships. These hierarchies allow economists to compare interaction structures systematically while preserving distinctions that matter for equilibrium behavior and policy.
Binary Dichotomies and Conceptual Oppositions
Interaction theory makes heavy use of binary and contrastive classifications to mark structural boundaries between fundamentally different interaction regimes. These dichotomies are not descriptive conveniences; they identify qualitative shifts in strategic logic. Canonical examples include:
- Competitive vs. Strategic interaction, distinguishing price-taking environments from settings where agents explicitly anticipate one another’s actions.
- Simultaneous vs. Sequential interaction, distinguishing environments where moves occur at the same time from those governed by order and timing.
- Cooperative vs. Non-cooperative settings, distinguishing interactions governed by binding agreements from those without enforceable coordination.
- Market-based vs. Hierarchical coordination, distinguishing decentralized price systems from command or organizational structures.
Crossing these boundaries changes equilibrium concepts, admissible strategies, and feasible institutional arrangements.
Scale and Context Dependence
Classifications in Interaction are highly sensitive to institutional and contextual scale. The same agents may interact competitively in one context and hierarchically or cooperatively in another. Similarly, interaction structures may fragment or consolidate as the scale of analysis shifts—for example, competitive markets at a local level may appear as strategic blocs at an international level. Interaction classifications therefore function as contextual partitions, tuned to the institutional environment, enforcement structure, and scope of interaction under study.
Structure vs. Function (Interaction Forms vs. Strategic Behavior)
A defining feature of Interaction classifications is the separation between interaction form and strategic behavior. Classifications identify the type of interaction environment—such as a market form, game type, or institutional arrangement—while strategic behavior, beliefs, and learning processes are treated separately. This distinction allows economists to compare how different behaviors play out within the same interaction class, or how similar behaviors yield different outcomes across classes. The classification fixes the structural constraints within which strategic behavior operates.
Universal Role of Classification in Interaction
Classification is indispensable in Interaction because rules, equilibria, and welfare outcomes are class-specific. Whether prices form, coordination succeeds, or institutions stabilize depends critically on the type of interaction in play. By explicitly classifying interaction environments—markets, games, bargaining settings, hierarchies, and networks—economists can determine which analytical tools apply and where standard results break down. In this way, classifications in Interaction serve as the structural backbone of strategic and institutional analysis, enabling comparison across settings and supporting coherent explanations of collective economic behavior.