Palmarius (Palmer), Thomas (c.1350–c.1415), Anglo-Irish Dominican friar, was born probably in Palmerstown, Co. Kildare. Nothing seems to be known of his background or early years. His first appearance in historical documentation is as a friar of Winchester convent in 1371, where he was still present in 1376. He was made an acolyte there on 20 September 1371, subdeacon on 22 December 1375, and priest on 20 September 1376. He was assigned by the general chapter of the order, held at Carcassone in 1378, legere sentencias – that is, to read the ‘Sentences’ of Peter Lombard, the prescribed text for bachelors of theology – at Cambridge in 1378–9. He obtained a doctorate of theology there in 1393. He made the papal schism of Avignon the subject of a determination in the faculty of theology at Oxford university c.1396, which was subsequently published as the ‘Determinatio in materia schismatica’, one of a number of Thomas's surviving written works, a copy of which John Leland reported as being formerly in the library of Westminster Abbey (Collectanea, iv, 49).
One of his most public engagements was when he engaged successfully in disputation with magister Peter Payne (‘Peter the Clerk’), an Oxford Lollard and supporter of Wyclif, in 1404/5 on the lawfulness of the vernacular versions of sacred scripture. He was a senior monk of the Dominican house of Holborn, or Blackfriars. Unlike his fellow countryman, Richard FitzRalph (qv), archbishop of Armagh, a section of whose ‘Summa de quaestionibus Armenorum’ was quoted by Peter in support of the use of the vernacular texts of scripture, Thomas was opposed to the use in the schools or by layfolk of any translation of the Vulgate. His arguments are summarised in the short tract, ‘De translatione sacrae scripturae in linguam Anglicanam’. Thomas had earlier in 1393 defended the former Lollard Nicholas of Hereford against the charge of backsliding.
Thomas achieved a succession of high offices in the English Dominican Order. The highest was his appointment in 1393 as prior provincial of the English order, of which he was absolved on 28 June 1396. He then became prior of London convent in 1397, a post that he vacated in 1407. In April 1384 he became visitor of the visitations of London and the marches. He is known to have preached before Richard II (qv) at Southampton on 29 June 1384, and at All Saints church, Eltham, Kent, in 1389. He also preached before Henry IV at Eltham on Palm Sunday 1403. He was present as a judge at the trials of John Oldcastle for heresy and treason in 1413 (Oldcastle was later convicted and sentenced to death), and again of Joseph Claydon for heresy in August 1415, which is the last known reference to Thomas.
The Irish antiquarian James Ware (qv) first confused this Thomas Palmer with Thomas of Ireland (qv) and the earlier Thomas Hibernigena (qv) in De scriptoribus Hibernicis (1639), whence it was taken by Luke Wadding (qv) (d. 1657) into his Scriptores ordinis minorum (1650) and thence into modern biographies. The three were successfully disentangled by Quétif and Échard in their Scriptores ordinis praedicatorum (Paris, 1719), i, 744–6, and later by Hauréau, Histoire littéraire de la France, xxx, 398–408.