As Donald Davidson once reminded us, differences in opinions are only possible with a huge amount of shared opinions or beliefs presupposed.  Otherwise we would not have disagreement but incomprehension. And that means that a difference in opinion is only possible if and when we presuppose a large set of shared knowledge and beliefs.
In a sense knowledge is very trivial. It’s what is shared and what is presupposed to make meaningful disagreements even possible. (An other function is that it is that on which we rely to justify a certain claim. In a sense knowledge doesn’t need justification, it is, what justifies others. But I leave this aside.) We don’t congratulate each others for having obtained knowledge pieces like “Grass is green”, “The sky is blue”, “2 + 2 = 4”. Knowledge is not only what is presupposed and shared to make differences in opinions possible, it is what we do not or do no longer articulate or emphasize in order to have a meaningful disagreement.
So we come to two points: Firstly, knowledge shows up in what is implicitly presupposed to make even disagreement possible; secondly, it is something we have in common in order that you and I may have individual different opinions at all.
Knowledge is what we share, and what is shared unanimously. Situations of unanimity are such that distinctions like subjective vs. objective, I vs. Thou, and the parlance of perspectives don’t even arise. They do not arise until we have a moment of disagreement, of differences in opinions. (In a sense not knowledge, but belief and opinion are the more problematic phenomena to define and to explain. In most cases the predicates of belief and opinion have explanatory value only because knowledge has none.) To be more precise: Knowledge as shared by a We is presupposed in order to have opinions that are being hold by an I and a Thou. In cases of unanimity those differences simply do not occur, and accordingly the distinctions between subjective and objective, me and you simply do not arise. In moments of unanimity there is a We, but not an I, not a subjective perspective, and no task to find an epistemic relation from the opinion to the knowledge and from the individual person to the We.
Imagine a lake whose surface is plane and calm. Then someone throws in a stone and the circles keep spreading from the centre to the distance until the water is calm again. In the same manner the We is a state of unanimity. In case of conflict, of differences of opinion this We splits up into an I and a Thou, into me and you, into subjective and objective, with the aim of reconciling the differences. If successful, the We returns to its state of unanimity. If not, the participating people leave the discussion. (I simplify matters here.) But that means that the distinctions between the I and the Thou, between persons and perspectives, don’t lie in the persons themselves, but in the We. Accordingly, I and Thou, subjective and objective, unanimity and disagreements are not phenomena in themselves, but qualities, properties or states of a We. Turned differently, they indicate the present state of a We.
The dynamic is somewhat like this: The unanimous We is “disturbed” (or “aroused”, like the surface of a lake) by an interference. It divides itself into I-s and Thou-s, tries to ease the disagreements with the goal of returning to the state of unanimity again. Subjective and objective, I and Thou, me and you, are primarily ways a We ascertains itself about its own present state, not so much phenomena in themselves.
But what, then, is a person? If there is no I, no Thou, no me or you, then what are we, and how are we distinct from all the others we experience us not to be and them not to be us?
The individual person, the I, does not arise from delineation to others, but from the understanding what one has in common with others, through identification. (I guess this is so even in the time of the terrible twos.) Most of the time we make our experiences through and with other people or in the proximity of other people. (It is rather late in one’s live and more the exception that we make impressive or lasting experiences with nature, with art, etc., on our own, alone.)
Again an image may help: See the movements of a flock of birds. They circle in the skies, one takes the lead, only to be succeeded by another. The movement of the flock depends on the number of birds, small flocks rush in a direction like an arrow, big flocks move more like oil in a bowl, slowly from one side to the other, up and down. But in doing so the birds always circle around a centre, and the centre is created by the birds circling around it.
In the same way we can understand a person as a flock of other persons, a flock of its voices, dreams, moods and sentiments, memories, pathologies, goals, handicaps. They circle around, one takes the lead for a while just to be succeeded by another. And in this overall movement these voices and memories circle around a center, creating it by circling around it. The I in the middle. So what we get at is that a person is a We too, consisting of different voices, memories, people. Just look at how all our lovers (former and present), how our families stay with us and talk to us, even when they are long gone. A chorus of souls in a soul.
As a consequence the We is not bound to the present or the skin of the body, but spread out through space and time, reaching to ancestors and grandchildren alike, to people far away and deep down in us, across places and landscapes. A person is a We, an assembly of voices, a flock of birds. And whoever leads this gathering should be hospitable and offer them ghosts a place at the fire and a coffee to drink.
 ∧ Donald Davidson, “On the Very Idea of a Conceptual Scheme (1974)”, in: Donald Davidson, Inquiries into Truth and Interpretation, 2nd ed., Oxford [et al.]: Clarendon Press, 2001, p.184.
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