ABSTRACT
Ontological agents, which may therefore fulfill the agent role of an action, comprise humans, animals, robots believed to be intelligent, culturally postulated counterintuitive agents, and fictive counterintuitive agents a slightly broader class of entities can be called agentive categories, to incorporate anything that can act by itself, such as non-goal-directed natural forces. At the same time, some linguists introduce natural cause as a thematic role for verbs whose agent can be a natural force. The agent role and the natural cause role will be referred to together as agentive roles. A generalized version of the agency filter axiom requires that only agentive categories may fulfill the agentive roles. Accordingly, both John and the heat can melt the wax without any anterior cause. Rituals are, typically, either exciting, infrequent, and belonging to the special-agent ritual category, or emotionally less imposing, frequent, and belonging to the special-patient or special-instrument type.
