This article investigates the linguistic work of the English Jesuit James Adams (1737–1802). It places Adams’ work in the socio-cultural context of 18th-century linguistic writing, in particular with respect to two ongoing debates: (1) on a monogenetic vs. a polygenetic origin of language and (2) on the origins of Scots. Both of these were highly ideological debates, in the first case between a biblical and a scientific world view, and in the latter between those who were content with the political state of affairs (the Union of Scotland and England), and those who would rather have had an independent Scotland. Adams manages to reconcile linguistic evidence with monogenism, while his views on language and dialects are guided by ‘Christian phil­anthropy’. They contrast sharply with those of many of his contemporaries. In his “Vindication of the Dialect of Scotland”, which is the central part of the “Appendix” of his Pronunciation of the English Language (published in 1799), Adams strongly votes for Scottish linguistic independence, though not for political independence, even advocating a separate Scots spelling. The analysis of this work shows that his attitude to dialects is informed by his education and life as a Jesuit in the 18th century, his belief that all people are created as equals, his didactic concerns as a teacher, and the personal experience of an extended stay in Scotland.