O'Mahony, Conor (1594–1656), Jesuit academic and author, was a native of Muskerry, west Co. Cork. Little of his early life is known until his entrance into the Irish College at Seville, probably in 1614, where he studied philosophy and theology for three and four years respectively, ultimately graduating as master of arts and doctor of divinity. He was admitted to minor orders on 7 June 1618 and was ordained a priest on 21 December 1619. The following year he was almost expelled from the college for unspecified misdemeanours. In 1621 he entered the novitiate of the Society of Jesus in Lisbon and took the name ‘Cornelius a Sancto Patricio’. In and around 1626 he went to the college of San Miguel in the Azores, where he was to spend seven years as professor of moral theology. He is also recorded as having performed great service to the victims of an earthquake and eruption at Ponta Delgada in 1630. O'Mahony held the chair of moral theology at the university of Evora (1633–5), and in 1636, the year of his final profession as a Jesuit, was transferred to Lisbon, where he became professor of dogmatic theology for five years.
The experience of living in Portugal during the Braganza revolt against the Spanish Habsburgs and, almost certainly, personal acquaintance with several of the Jesuit scholars who provided intellectual justification for the Braganza position, were of critical importance in conditioning his own reaction to rebellion in Ireland and the formation of the Confederate Catholic Association in 1642. In 1645 he published in Lisbon the text on which his historical reputation rests, the Disputatio apologetica de iure regni Hiberniae pro catholicis Hibernis adversus haereticos Anglos, a two-part work consisting of a ‘disputatio’ and an ‘exhortatio’.
O'Mahony's purpose was to demonstrate that the ‘Hiberni’, a generic term which he used to denote all the catholics of the island, had the right to reject the authority of the monarchs of England over Ireland. In the ‘disputatio’ he first rehearsed a series of arguments which might be advanced to legitimise English authority, and then proceeded to attack them. His arguments were intensely legalistic and the historical underpinning was somewhat weak. The second part of the ‘disputatio’ was relatively stronger. It adapted the work of Bellarmine, Suarez, and Molina to build a case that, even if English monarchs had once legitimately ruled over Ireland, the Irish retained the right to eliminate their authority because of the lapse into heresy of Charles I and his two predecessors. The ‘exhortatio’ that followed, drawing heavily on biblical example, urged the Irish people to choose a new catholic and native monarch and to eliminate all the remaining heretics in the island.
Although emotional resonances with O'Mahony's book can be detected in some manuscript material produced after the rebellion of 1641, it received almost no public support among the audience for which it was avowedly written, the Confederate Catholics of Ireland. The book ran counter to the dominant current in Irish catholic political ideology, which stressed the legitimacy of Stuart rule. In 1645, the year of its publication, even the clerical convocation, the most militant group within the association, dismissed out of hand the idea that Charles was not the confederates’ legitimate king. Radical catholics within the association opted to refer to the confederate oath of association to justify their objectives, rather than to O'Mahony's dangerously divisive argumentation. Moreover, the frank approbation in the ‘exhortatio’ for the killing of 150,000 protestants since the initial rebellion was particularly unwelcome to the great mass of the Confederate Catholic leadership, who wished to avoid any link to the alleged massacres of 1641. The confederate executive ordered that copies of the book should be burned by the common hangman, and evidence has survived that the city of Galway independently expressed its abhorrence for the book and its author. Peter Walsh (qv) is also said to have preached nine sermons against the book in Kilkenny.
Although it attracted little support in Ireland, O'Mahony's text did contribute to the divisions that racked the confederate association in the later years of the decade. It was feared in some quarters that his book was intended to provide the theoretical underpinning to an attempt by Owen Roe O'Neill (qv) to wrest the sovereignty of Ireland from the Stuart monarchy. O'Mahony's work also increased the difficulties of the papal nuncio Rinuccini (qv), who was suspected of plotting to establish papal suzerainty over Ireland and who was accused in Rome by Sir Kenelm Digby of tolerating the Disputatio apologetica. Rinuccini may also have refused to hand John Bane, a parish priest in Athlone, over to secular justice after he was discovered with a copy of the book in his possession. For his part the papal nuncio related some of the hysteria evoked by the text to the fears of secular landowners that O'Mahony's arguments might be used to delegitimise their continued possession of former monastic property. The divisive effect of the book seems to have been heightened by the general lack of knowledge concerning the true identity of its author. This may well have been a conscious decision on the part of O'Mahony, as the title page of the book gave a bogus place of publication. Alternatively, the reference to Frankfurt as the place of publication in the title imprint may have been a device to escape the attentions of the Portuguese censor. As it transpired, the efforts of the English ambassador, Sir Henry Compton, resulted in two separate condemnations of the text in Portugal on 6 April and 5 December 1647, although no action seems to have been taken against O'Mahony. In the post-confederate period the Irish Jesuit did reveal himself as the text's author to Patrick Plunkett (qv), bishop of Ardagh. Having been in good health, he died suddenly 28 February 1656 at the Jesuit House in Lisbon.
After his decease, copies of the Disputatio were never common: the authors of the Commentarius Rinuccinianus, for instance, had never seen the text but it did enter into later Irish protestant mythology. In 1689 Richard Cox (qv) described it as ‘a most treasonable and scandalous book’ and observed that it was not publicly condemned by the congregation of catholic clergy in Dublin in 1666. A small number of copies of the work were reprinted, apparently in 1826, probably as part of the campaign against catholic emancipation.