Where does agent collide?

In an economic model, an agent is a decision-making unit: an entity with preferences and a choice set that picks actions to maximize an objective, such as a household maximizing utility or a firm maximizing profit. Much of modern macroeconomics runs on a single representative agent that stands in for a whole population, a shortcut Kirman questioned in 1992 by showing the aggregate need not behave like anyone in it. The word also names one side of a delegation: in Jensen and Meckling's 1976 principal-agent account, the agent is the party engaged to act for a principal. Either way the referent is a modeled chooser, not a substance and not a grammatical role, and what makes something an agent here is that it holds an objective and decides.[1][2]

Unit

A decision-making unit in a model

Recovery means

Not applicable

Measured by

Not measured directly; inferred from choices under an assumed objective and constraint set

In artificial intelligence, an agent is anything that perceives its environment through sensors and acts on it through actuators, and a rational agent is one that chooses the action expected to maximize a performance measure. Russell and Norvig built the standard textbook around this definition, which stretches from a thermostat to a software assistant. The referent is a system coupled to an environment, individuated by its sensors, actuators, and objective, not by any inner life. It shares the language of maximizing an objective with the economic agent, but this agent is engineered and runs rather than being posited on paper, and an environment, not a market, is what it acts on.[3]

Unit

A system coupled to an environment

Recovery means

Not applicable

Measured by

Performance measure over an environment; task success; degree of autonomy

In linguistics, the agent is a semantic role: the participant that deliberately or causally brings about the action a verb names, the doer in a sentence such as "the cook broke the egg." It is one of the thematic roles that tie a verb's meaning to its syntax. Dowty's 1991 account traded the sharp category for a cluster of proto-agent properties, volition, sentience, causation, and movement, so that arguments are more or less agent-like and the most agent-like one tends to become the subject. The referent is a role carried by an argument and assigned by the verb, not an entity in the world, and a grammatical agent can be inanimate, as the wind is in "the wind opened the door." Fillmore had introduced the agent case earlier, in 1968.[4][5]

Unit

A thematic role assigned to a verb's argument

Recovery means

Not applicable

Measured by

Not measured; identified by argument-structure and entailment tests