by Scott F. Aikin and Robert B. Talisse
Textbook discussions of logic often proceed as if reasoning were a relatively simple, albeit challenging, process. One simply begins from one's evidence, articulates one's premises, and then, by means of the application of rules of induction or deduction, one draws one's conclusion. On this common picture, the assessment of reasoning fixes on two main elements: (1) the quality of one's premises given one's evidence; and (2) the quality of the inference by which one's conclusion is drawn. From this perspective, there has emerged a wealth of important theorizing about the various logical properties that reasoning can embody, including validity, soundness, cogency, and supportiveness.
Yet we all know that in real-time contexts, reasoning is a far more complicated affair. For one thing, real-time reasoning occurs under conditions where one must draw one's conclusion on the basis of partial or conflicted evidence. We often must reason while relevant evidence is still being gathered and evaluated. Reasoning, under these conditions, inevitably involves the drawing of provisional conclusions based on premises rooted in incomplete evidence. Consequently, reasoning in real-time is largely a matter of coordinating and calibrating one's conclusion with an unsteady and still-developing evidential environment. Moreover, much of the reasoning we do as issues develop is reason in light of the fact that we often already have a view on the matter. We've drawn a conclusion earlier, and now we are revisiting the question of whether we must revise it. That is, we must not only reason critically before we form beliefs, but we also must reason critically after we form them, too. To employ a philosopher's distinction: textbook treatments emphasize the role reasoning plays in the acquisition and justification of beliefs, whereas in real-world contexts reasoning has mainly to do with the maintenance and revision of beliefs.
Of course, in real-world contexts, even modest changes of belief can be practically costly, and sometimes psychologically taxing. Unsurprisingly, then, a lot of real-world reasoning aims at preserving one's belief in the light of new and unanticipated evidence. In confronting new data, we understandably try to hold on to the belief we formed previously. One sure-fire way of accomplishing this is to show how the new evidence lends further support to what we already believe. Failing that, we can also attempt to establish that the new data poses no challenge to the existing belief. To be sure, there are methods of belief-preservation that are intellectually vicious and dishonest; what is called rationalization is one case in point. Nonetheless, holding one's belief steady in the face of new data is not intrinsically degenerate, and, again, a lot of important work has been done in argumentation theory and epistemology that attempts to give an account of intellectually virtuous belief-preservation in the face of new evidence. Of course, we cannot survey this work here. But there is one important feature of virtuous belief-preservation that we want to highlight.
We can capture the points just made about real-world reasoning by saying that much of our reasoning is aimed at making a case. Again, we often must draw provisional conclusions from incomplete data, and, given the costliness of belief-revision, we must attempt to preserve insofar as we can our preliminary conclusions in the face of new and unanticipated evidence. We might say, then, that in contexts where evidence is still being gathered, once we reason our way to a conclusion from our initial evidence, we then must reason back from the conclusion to accommodate the new data. In other words, we draw from the various considerations available to us at the time in building support for our antecedently-drawn conclusion.
The important thing to notice is that when one is making a case for a conclusion, one is engaged in a comparative enterprise. Unlike the demonstrations and proofs of formal logic, making a case involves showing how newly-collected data either contributes to the existing support for one's conclusion, or at least does not detract from it. However, the degree of support that is enjoyed by one's conclusion is partially a matter of the degree to which opposing conclusions are supported by the available data. A new piece of evidence lends no real support to one's own conclusion unless it either speaks against or does not affect its competitors. Making a case, then, must have a two-steps. First, one must show how new data lends support to (or does not detract from the existing support of) one's conclusion. Second, one must show, at the very least, that the new data does not provide an equal degree of support for opposing conclusions.
This second comparative dimension of making a case is frequently overlooked in real-world argumentation. Often in these contexts one finds reasoners simply showing that new data support or can be accommodated by their antecedent view. Rarely do they take up the task of comparing the degree of support the new data lends to their own view to the impact of that very data on their opponents' views. And this failure to compare is a mark of the intellectually vicious kind of belief-preservation. Until the comparative force of new data is reckoned, one engages only in rationalization, cherry-picking, or casuistry on behalf of one's conclusion; one fails to make a case for it.
A few lessons arise from these observations. First, we can see why a kind of intellectual conservatism arises from the procedural tasks of cognitive rationality – if one is allowed to form beliefs in medias res, then one will be inclined to reason in light of those beliefs going forward. Second, we can see why a certain vice of conservatism arises, too – if one is looking only at the rational considerations on the maintenance of the belief, one misses the comparative work of assessing how the new evidence affects the status of other commitments. Third, and finally, we can see the importance of John Stuart Mill's requirement that one know the views of one's critics and opponents well, too. Without that knowledge and comparative work, what looks from the inside as manifest rationality is actually an exercise in rationalization.
Our point can be summarized like this. Much real-world reasoning is devoted to making a case for an antecedently-drawn conclusion in the light of new evidence. If they are to avoid the intellectual vices associated with rationalization and other failures when making a case, reasoners must consider the ways in which new data impact the support not only of their antecedent view, but also of the opposing views.