Sin and the Law
It follows that Paul would be making a much stronger statement—but also a much more “localized” one—about the relation between sin and the Law. If the sin of Adam and Eve was sexual—either the discovery of sexuality itself or a change in the nature of sexuality—, a view that was held throughout much if not most of ancient interpretation—then it was the positive commandment to have children that led them into it, through the occasion of Sin's (the Serpent's) manipulations. They had been commanded to procreate but also to avoid sexual desire. No wonder that the Serpent (Sin) was able to exploit the commandment to cause them to sin! Within any interpretation that begins with the assumption that sexuality is sinful, as it certainly was for many Jews and Christians in late antiquity, the blessing of procreation is going to be a logical and hermeneutical conundrum, as witness the myriad difficulties of the Church Fathers in sorting out the sequence of events here (Anderson 1989).
Adam's double bind, commanded on the one hand to procreate and on the other to avoid eating of the fruit of the tree of (carnal) knowledge, is the type of Jewish humanity under the flesh, commanded to procreate but also to not have lustful desires, let alone act on them. The Christian, however, having been released from procreation and thus from sexuality, can conquer her desires and bear fruit for God. On this reading, Paul's references to “bearing fruit,” καρποφορήσωμεν, whether for God, i.e., spiritual fruit in verse 4, or for death, i.e., children in verse 5, are precisely an allusion to the commandment: Be fruitful and multiply, of Genesis 1:28.