Oliver O’Donovan, Self, World and Time, pp. 45-47:

Discussion is a shared struggle to reach truth and overcome error.  It may often unfold in an eristic form, as an exchange of arguments and rebuttals.  (We see this especially in the phenomenon of the combative personality, the individual who has difficulty thinking through anything at all without picking a quarrel, thrusting discussion-partners into the role of opponents.)  The eristic form has its own right.  Differences at the outset provide the stimulus for thought to progress dialectically.  As we know from politics, the discussion cannot get off the ground if either party denies the other the right to its independent starting point; when the condition for entering discussion is that a key point is surrendered in advance, no discussion can occur.  Paradoxically, then, discussion depends at once on conflicting assertions and on mutual concessions.  But what is asserted and what is conceded are not the same.  We may enter a discussion in perfect confidence that we are in the right against our opponent.  We may be sure that once we have explained ourselves fully, no shred of an answer can be made.  Yet we may still sense the need to prove our impregnability in a clash of steel, to gain real knowledge of what the opponent actually says when confronted with our case and to discern, if we can, what alternative reasoning can be brought to bear against our own.  Even the most confident discussant can expect to learn something from the exercise.

Let us suppose that I disapprove strongly of the death penalty, and take up the cudgels against someone who defends it.  As our discussion proceeds, certain things will become clear.  One is that there are various reasons for disapproving of the death penalty, some of which may plausibly claim a perennial moral truth, while others are more circumstantial.  If my opponent forces me to think hard, I shall understand better what social and historical conditions have made the death penalty appear reasonable to past generations, and I shall have to ask whether those conditions could ever recur.  I shall come to see that my view of the matter is part and parcel of a wider philosophy of penal justice and governmental responsibility, and I shall be forced to elucidate that philosophy more fully and to test its capacity to shed illumination on other questions, too.  None of this could I have gained from talking to those who agreed with me.  What it amounts to is that if at the end of the day I still say, ‘I disapprove of the death penalty!’ I know much better than before what I mean by it.

. . . Individual moral thinking is social not only in its beginnings but in its ends.  Our most secret deliberations, our most independent conclusions, are directed towards a community of understanding.  We think as though trying to win the approval of a judicious audience hidden in the darkness of the stalls, ready to applaud our point of view when the lights go up.  It is not simply that without a community of inquiry our thought cannot begin.  If we cannot envisage a community of agreement our thought cannot have any end in view, either.

When parties to a discussion punctuate it with decisive stands expressed in the first-person singular (‘I passionately oppose . . . !’) that is neither the beginning nor the end of moral thought.  It is a moment in-between, a moment at which the common inquiry has broken down and the common agreement at which thought is aimed has disappeared from view.  The affirmation of the ‘I’-position is a strategy for regrouping and relaunching the discussion, as when a standard is thrust into the ground and the scattered soldiers gather to it.  Rhetorical inebriation may make the standard-bearer forget that he is part of an army, but that is the logic of it.  In the moment of affirmation the ‘I’ takes responsibility for the whole, making a decision on what must be held in common by all.  And so together with the right of a distinctive point of approach must be granted also an anticipation of persuasion.  Serious discussion is entered expectantly, with a view to finding a common perspective which makes sense of an object of hope, still to be looked for; yet it is something to be discovered, not devised.  It is not a negotiated add-on to the prior private convictions of the discussants; it is the realization of those convictions, which, though they may have been held privately, were intended socially.