Selection From Alasdair MacIntyre, Three Rival Versions of Moral Inquiry: Encyclopedia, Genealogy, and Tradition, (Notre Dame, IN: University of Notre Dame Press, 1991), 87-89.
What saved the twelfth century from eclecticism was the existence of an overall framework of belief within which the different uses of different parts of ancient philosophy had to be put to work and in terms of which they had in the end to be justified. . . . In this application [of dialectic to theological questions], three different and originally independent strands in the intellectual development of the Augustinian tradition came together. The first concerned the use of the quaestio. Beginning from Augustine's own formulation of quaestiones there had developed by the eleventh century the custom of interpolating quaestiones into commentary on Scripture, both spoken and written, and gradually the proportion of space devoted to such quaestiones rather than to commentary increased. In the statement of the alternative solutions to a quaestio and the arguments pro and contra for each solution more and more was made of materials provided by the subordinate liberal arts of grammar and dialectic, and at the same time, especially in the eleventh century, quaestiones were posed concerning the truth of falsity of certain theological doctrines and not simply concerning the interpretation of texts. So emerges a conception of enquiry as consisting in the sequential posing of a series of related quaestiones through which the problems concerning some particular subject matter were posed in a sequential systematic way.
To this development in the quaestio there corresponds a development in the use of dialectic. The master-text for dialectic in the earlier Middle Ages was that provided by Boethius in the De topicis differentiis, a work which followed Aristotle's Topics closely, and which, like Aristotle's work, deals with what is distinctive in dialectical as contrasted with demonstrative arguments. Certain differences between dialectic and demonstration are crucial. Demonstrative arguments state and order already known truths, vindicating the status of such truths as certain knowledge, as parts of some science. A perfected science exhibits its form as a chain of such arguments, descending from its necessary first principles to its subordinate conclusions. By contrast dialectical argument is exploratory. Dialectic is the instrument of enquiry which is still in via. It is through dialectic that we construct demonstrative arguments, and thus while in demonstrative reasoning we argue from first principles, in dialectical we argue to first principles. Since on the Augustinian conception the movement of enquiry is towards first principles, dialectic is necessarily its argumentative instrument. But since dialectic argues from premises so far agreed, or at least not put in question, to conclusions which are not necessary truths but only the most compelling conclusion to be arrived at so far, the work of dialectic always has an essentially uncompleted and provisional character. A dialectical conclusion is always open to further challenge.
A third strand of intellectual development was the systematic growth in the making of distinctions in types of sense, not only in explicating Scripture but also in understanding secular texts, so that in time there arises a new genre, a set of works characteristically entitled Distinctiones. The technique of making such distinctions of sense was enriched by the contributions of grammarians as well as of commentators. And this technique could then become an additional instrument of dialectical argument, which in turn could serve the purposes of systematic enquiry organized as a succession of quaestiones. Thus what had been three relatively independent strands of development came together in the newly comprehensive works of the twelfth century.