Front Page Titles (by Subject) Chapter 5: Incest - The Principles of Moral and Political Philosophy
The Online Library of Liberty
A project of Liberty Fund, Inc.
Search this Title:
Chapter 5: Incest - William Paley, The Principles of Moral and Political Philosophy 
The Principles of Moral and Political Philosophy, Foreword by D.L. Le Mahieu (Indianapolis: Liberty Fund, 2002).
About Liberty Fund:
The copyright to this edition, in both print and electronic forms, is held by Liberty Fund, Inc.
Fair use statement:
In order to preserve chastity in families, and between persons of different sexes, brought up and living together in a state of unreserved intimacy, it is necessary by every method possible to inculcate an abhorrence of incestuous conjunctions; which abhorrence can only be upholden by the absolute reprobation of all commerce of the sexes between near relations. Upon this principle, the marriage as well as other cohabitations of brothers and sisters, of lineal kindred, and of all who usually live in the same family, may be said to be forbidden by the law of nature.
Restrictions which extend to remoter degrees of kindred than what this reason makes it necessary to prohibit from intermarriage, are founded in the authority of the positive law which ordains them, and can only be justified by their tendency to diffuse wealth, to connect families, or to promote some political advantage.
The Levitical law, which is received in this country, and from which the rule of the Roman law differs very little, prohibits* marriage between relations, within three degrees of kindred; computing the generations, not from, but through the common ancestor, and accounting affinity the same as consanguinity. The issue, however, of such marriages are not bastardised, unless the parents be divorced during their life-time.
The Egyptians are said to have allowed of the marriage of brothers and sisters. Amongst the Athenians, a very singular regulation prevailed; brothers and sisters of the half-blood, if related by the father’s side, might marry; if by the mother’s side, they were prohibited from marrying. The same custom also probably obtained in Chaldea so early as the age in which Abraham left it; for he and Sarah his wife stood in this relation to each other: “And yet, indeed, she is my sister; she is the daughter of my father, but not of my mother; and she became my wife.” Gen. xx. 12.
[* ]The Roman law continued the prohibition to the descendants of brothers and sisters without limits. In the Levitical and English law, there is nothing to hinder a man from marrying his great-niece.