“The art of speaking in a probable way”

Down below, in response to the question “how do you know?” Steve Hays commented:

Why must we “know” that we have the right interpretation? Why is it not enough to have the most reasonable interpretation?

If God holds us responsible for what we can know, and if our interpretations come down to the most reasonable or probable interpretation, then that’s all that God requires of us.

A Roman apologist like Bryan Cross will tend to propose that God’s method for creation and revelation involves rigorous logical deduction. The problem with that is, the history that God has given us is not a rigorous sequence of causes and events; Scripture and history are not comprised of rigorously logical arguments or sets of arguments.

For Rome, and for Bryan following, however, “the Church” (meaning the “Roman Catholic Church”) was given by God in a logical and an ontological way in Matt 16:18, never to change. The same exact ontological structure that it has today was ontologically in place at Matt 16:18, and therefore it (and all of its rules and strictures) must be obeyed as if Rome’s rules and strictures come to us directly from the very mouth of Christ.

That, of course, is merely an assumption: it is an empty, unprovable assumption upon which the whole Roman edifice is resting: all of its historical claims to authority, its claims of epistemological certainty, its sacraments, its treadmill of religious practices – all of the Roman Catholic “things you gotta do” to appease God are resting upon a meaningless claim of authority.


There is a way of thinking about these things that is more respectful of both the natural ordering and the history of things, bypassing strictly logical deduction in favor of a more inductive, inferential way of thinking.

This is outlined by Richard Muller in his work “The Unaccommodated Calvin”:

The prominence of the locus or topos in the dialectic of the later Middle Ages, the Renaissance, and the Reformation rested in no small degree on the perception that the elicitation of topics or loci from the subject under examination provided the optimal point of departure for the examination of the subject.

Melancthon commented that Cicero’s Topics described “the method of locating arguments” and of “amplifying or explaining discourse”. He owed his point to the efforts of Rudolf Agricola (1443-85), whose De invention dialecta libri III (1480/1515) had been championed by Erasmus and echoed In Erasmus’s popular treatise on argument and the gathering of materials for argumentation, De copia (1512).

Agricola was not, by intention, a creative thinker: his hope was rather to renew interest in the classical disciplines. But his emphasis on grounding logic in rhetoric and on deriving the rules of logic from the examination of the works of great classical orators led to the view of logic as an art of probabilities rather than a science of necessities—“dialectics,” he wrote, “is the art of speaking in a probable way”—based on the examination of fundamental topics or loci.

The basic work of this rhetorical logic, “invention,” was defined by Agricola as the location of proof or grounds of argument in and through the identification of the loci, which is to say the “places” or the topoi in which they might be found.

Muller, R. A. (2000), “The Unaccommodated Calvin”, Oxford, UK: Oxford University Press, Pgs 108-109.

This is not a 15th-century way of thinking. Some of the better thinkers in history have looked at life in these terms and understood that life is not a rigorous argument; it is not a series of “necessary conclusions”.

As [Eleonore] Stump has argued, the movement of later medieval logic prior to Agricola had tended away from a logic of probabilities toward a logic of necessary conclusions. With reference to Aristotle’s and Cicero’s Topics, a “concentration on the nature of the rules for consequences” tended to subsume the logic of the Topics under the stricter models of the Analytics [one of Aristotle’s works].

(Of course, Aristotle himself did not make a strict division between logic and rhetoric: in the rhetorical forms of the Topics, logic is applied to persuasion, with the result that its structures are not quite as strict but still belong to the realm of logic.)

Agricola, by emphasizing the logic of Aristotle’s and Cicero’s Topics, pressed in the opposite direction: in Agricola’s model, dialectic focused on the Topics and, therefore, on probability and on the persuasive use of probable propositions. Agricola thus echoed a Ciceronian use of logic in persuasion and identified the “sources” or “seats” of argument (fonts or sedes argumentorum) as the knowledge found in basic loci or topoi and defined the dialectical study of the loci as “the art of establishing the probability or credibility of whatever had been proposed.

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I would be remiss if I did not digress here and note that Bryan Cross’s whole apologetic, when dealing with the history that has been presented to him, has been to suggest that a particular Roman Catholic doctrine “is not inconsistent with” some particular fact or set of facts from history.

“Not inconsistent with” simply is fancy-speak for “not totally excluded by”.

At its broadest level, Bryan’s defense of the nonexistent early papacy papacy (which is not necessarily Rome’s concept of the papacy – but we can assume they are at least close cousins) claims that it is “not totally excluded by” history. Yet at the same time, it is rendered “extremely improbable” by that same history.

(I call them “close cousins” because Bryan seems to think that his apologetic is better than Rome’s – more logically rigorous and therefore better suited in the polemical world that he’s trying to say he’s not participating in. In fact, I think Bryan has the hope some day that his apologetic arguments will be recognized by some pope as better than what’s already out there, and he’ll see his “Called to Communion” articles in a future edition of Denzinger.)

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It’s not as if Agricola (and later Erasmus) was pulling all of this out of a hat. This inductive methodology has much earlier roots. Back to Muller and Agricola:

… a strong element must also be noted in this development of dialectic: the basic connection between the loci or topica and the academic exercise of disputationes remained unchanged during this development of place logic. In Stump’s words, “the scholastic tradition of dialectic has its roots in Aristotle’s Topics,” the large part of which “is devoted to a method for finding arguments useful in dialectical disputations.”

Whether understood as providing the grounds for arguing logical consequences or as understood in the more rhetorical (i.e., the Agricolan) sense of establishing probabilities for the purpose of persuasion, the examination of loci or topica was foundational to argument and, therefore, to the construction of disputationes.

Moreover, from a methodological perspective, the virtual identity of the “maxims of dialectic, the sententiae or “maxims” of theology, and the loci communes of rhetoric was noted specifically by Alain of Lille at the end of the twelfth century—just as the application of the locus method to theology was noted by both Erasmus and Melanchthon in the early sixteenth century.

This connection between the several exercises and methods, altered little by the Renaissance restructuring of the relationship between logic and rhetoric, remains in force in the theological loci communes and disputationes of the sixteenth-century Reformers and of their seventeenth-century successors as well (“The Unaccommodated Calvin” pgs 109-110).