[34] The marriage rights of criminals, degenerates, and other socially dangerous persons, are passed over here as not pertinent to the present discussion. For the same reason nothing is said of the perfectly valid social argument in favour of the individual right of marriage.
[35] Cf. Vermeersch, "Quaestiones de Justitia," no. 204.
[36] The argument in the text is obviously empirical, drawn from consequences. There is, however, a putatively intrinsic or metaphysical argument which is sometimes urged against the justice of the Single Tax system. It runs thus: since the fruits of a thing belong to the owner of the thing, "res fructificat domino," rent, which is the economically imputed fruit of land, necessarily and as a matter of natural right should go to the owner of the land. As will be shown later, the formula at the basis of this contention is not a metaphysical principle at all, but a conclusion from experience. Like every other formula or principle of property rights, it must find its ultimate basis in human welfare.
[37] Liberatore, "Principles of Political Economy," pp. 130, 134.
[38] Cf. Vermeersch, op. cit., no. 210; Ryan, "Alleged Socialism of the Church Fathers."
[39] "In IV Sent.," d. 15, q. 2, n. 5; and "Reportata parisiensia," d. 15, q. 4, n. 7-12.
[40] "De Justitia et Jure," tr. 2, d. 18 and 20.
[41] "De Justitia et Jure," c. 5, n. 3.
[42] "De Legibus," l. 2, c. 14, n. 13 and 16.
[43] "In Summa," 1ma 2ae, d. 157, n. 17.