The role of invention in contemporary rhetorical theory poses two problems: how to deal systematically with both the general topics and the more specific topics that respect the different modes of knowledge, and how to incorporate these topics into a conceptual framework that includes other elements of discourse for which theories or partial theories exist. The epistemology of Michael Polanyi offers three main concepts that suggest solutions for these problems: tacit inference provides epistemological grounds for adopting the informal procedures needed to treat a variety of subject matters; focal awareness applies to the interdependence of general and specific topics at two stages of the inventional process; and marginal control, an hierarchical principle, permits the accommodation of substantive and linguistic elements in a single framework. Such a framework based on Polanyian principles contains two major parts, one called "speaker, during the process of invention," the second called "audience, projected by speaker for the purpose of rhetorical invention." Tacit inference leads to a pattern of coherence for the speaker where meaning is linked with communicated material and relates to the audience through the topic, methods of argument, style, and linguistic elements that result in communication. (MAI)