The fathers of families, whose doctrine Plato censures, adopted this doctrine of reciprocity, and built upon it their exhortations to their children. "Be just to others: without that condition, you cannot expect that they will be just to you." Plato objects to their doctrine, on the ground, that it assumed justice to be onerous to the agent, and therefore indirectly encouraged the evading of the onerous preliminary condition, for the purpose of extorting or stealing the valuable consequent without earning it fairly. Persons acting thus unjustly would efface reciprocity by taking away the antecedent. Now Plato, in correcting them, sets up a counter-doctrine which effaces reciprocity by removing the consequent. His counter-doctrine promises me that if I am just towards others, I shall be happy in and through that single circumstance; and that I ought not to care whether they behave justly or unjustly towards me. Reciprocity thus disappears. The authoritative terms _right_ and _obligation_ lose all their specific meaning. [Side-note: Plato's own theory, respecting the genesis of society, is based on reciprocity.] In thus eliminating reciprocity--in affirming that the performance of justice is not an onerous duty, but in itself happiness-giving, to the just agent--Plato contradicts his own theory respecting the genesis and foundation of society. What is the explanation which he himself gives (in this very Republic) of the primary origin of a city? It arises (he says) from the fact, that each individual among us is not self-sufficing, but full of wants. All having many wants, each takes to himself others as partners and auxiliaries to supply them: thus grows up the aggregation called a city.[26] Each man gives to another, and receives from another, in the belief that it will be better for him to do so. It is found most advantageous to all, that each man shall devote himself exclusively to one mode of production, and shall exchange his produce with that of others. Such interchange of productions and services is the generating motive which brings about civic communion.[27] Justice and injustice will be found in certain modes of carrying on this useful interchange between each man and the rest.[28] [Footnote 26: Plato, Republic, ii. p. 369 B-C. [Greek: gi/gnetai po/lis, e)peidê\ tugcha/nei ê(mô=n e(/kastos ou)k au)ta/rkês a)lla\ pollô=n e)ndeê/s . . . metadi/dôsi dê\ a)/llos a)/llô|, ei)/ ti metadi/dôsin, ê)\ metalamba/nei, _oi)o/menos au(tô=| a)/meinon ei)=nai_ . . . poiê/sei de\ au)tê\n (tê\n po/lin), ô(s e)/oiken, ê)\ _ê(mete/ra chrei/a_.]] [Footnote 27: Plato, Republic, ii. pp. 371 B. [Greek: Ti/ de\ dê/? e)n au)tê=| tê=| po/lei pô=s a)llê/lois metadô/sousin ô(=n a)\n e(/kastoi e)rga/zôntai? _ô(=n dê\_ e(/neka _kai\ koinôni/an poiêsa/menoi po/lin ô)|ki/samen_.]]