He defines the following paradigms: (All explanations are direct quotations taken from 288).
- Positivist: The “belief system” of positivist inquiry, Guba asserts, include a “realist” ontology, and a “dualist/objectivist” epistemology, and values an “experimental/manipulative” methodology. That is, positivist inquiry holds that reality “exists ‘out there’ and is driven by immutable natural laws.” Knowledge is summarized in "time- and context-free generalizations" that sometimes are stated as "cause-effect laws." This paradigm assumes that the inquirer can adopt a "distant, noninteractive posture" toward reality, and can exclude "biasing and other confounding factors" from influencing the inquiry. The researcher states hypotheses in advance "in propositional form" and subjects these hypotheses to empirical tests under "carefully controlled conditions" (p. 20).
- Postpositivism: "Postpositivism," says Guba, adopts a "critical realist" ontology, a "modified objectivist" epistemology, and a "modified experimental/ manipulative" methodology. It holds that reality "can never be fully apprehended" (and therefore that investigators need always to be "critical" of their work), that objectivity "can only be approximated" (with help from readers and peers who constitute the "critical community"), and that research must employ multiple probes. Researchers need to work more in natural settings, to use more qualitative methods, and to depend more on grounded theory (theory grounded, that is, in local circumstances that give rise to the theory, instead of theory based on broad a priori generalities that positivism invites). Researchers need to acknowledge the role of "creative discovery," not just efforts at "verification" of theories or hypotheses, as central to inquiry (p. 23).
- Critical theory: The "critical theory" paradigm, says Guba, retains the "critical realist" ontology of postpositivism. But it adopts a "subjectivist" epistemology (no inquiry is "value-free:" a person's value system "mediate[s] inquiry") and a "dialogic, transformative" methodology (a methodology that seeks through dialogue to "transform" people by revealing how "oppressed" they are in their earlier "false consciousness," and by revealing "truth").
- Constructivist*: [T]he constructivist paradigm … adopts a "relativist" ontology, a "subjectivist" epistemology, and a "hermeneutic, dialectic" methodology. "Realities" (note the plural) are "multiple mental constructions [many different people do the constructing], socially and experientally based, local and specific." In the study of these realities, "inquirer and inquired into are fused”…; findings are created by the "process of interaction between the two." The methodology relies on individual constructions "elicited and refined hermeneutically, and compared and contrasted dialectically," with those of others - all this carried on with a view toward reaching "consensus" on at least some constructions (228). Larson emphasizes that the constructivist paradigm “accepts as potentially helpful the results from different research procedures, and in language popular today asserts the value of viewing an issue from multiple perspectives” (291).
*The constructivist paradigm represents a genuinely new paradigm (compared to the positivist paradigm).