The earliest tandem use of the terms was by the renowned medical geneticist, Dr. Victor McKusick, in his 1969 paper: "On lumpers and splitters, or the nosology of genetic disease.
Another early use emerged from a debate in 1975 between J. H. Hexter and Christopher Hill, in the Times Literary Supplement. It followed from Hexter's detailed review of Hill's book Change and Continuity in Seventeenth Century England, in which Hill developed Max Weber's argument that the rise of capitalism was facilitated by Calvinist Puritanism. Hexter objected to Hill's 'mining' of sources to find evidence that supported his theories. Hexter argued that Hill plucked quotations from sources in a way that distorted their meaning. Hexter explained this as a mental habit that he called 'lumping'. According to him, 'Lumpers' rejected differences and chose to emphasize similarities. Any evidence that did not fit their arguments was ignored as aberrant. 'Splitters', in contrast, emphasised differences, and resisted simple schemes. 'Lumpers' consistently tried to create coherent patterns. 'Splitters' preferred incoherent complexity. In a similar vein, historian of ideas Isaiah Berlin categorized thinkers as 'Hedgehogs' (lumpers) and 'Foxes' (splitters) in his essay on Leo Tolstoy, 'The Hedgehog and the Fox'.
Each approach has its well known problems. Lumping tends to create a more and more unwieldy definition, with members having less and less mutually in common. This can lead to definitions which are little more than conventionalities, or groups which join fundamentally different examples. Splitting often leads to "distinctions without difference", ornate and fussy categories, and failure to see underlying similarities.
For example, in the arts, "Romantic" can refer specifically to a period of German poetry roughly from 1780-1810, but would exclude the later work of Goethe, among other writers. In music it can mean every composer from Hummel through Rachmaninoff, plus many that came after.
Language families with lumper-splitter controversies include Ural-Altaic, Altaic itself, Austric, Nostratic, and Joseph Greenberg's similar Eurasiatic, his Amerind languages, Indo-Pacific, and Nilo-Saharan, and above all Merritt Ruhlen's Proto-World.
Splitters regard reconstruction of a common ancestor (protolanguage) via the comparative method as the only valid proof of relationship, and consider genetic relatedness to be the question of interest. American linguists of recent decades tend to be splitters.
Lumpers are more willing to admit techniques like mass lexical comparison or lexicostatistics, and mass typological comparison, and to tolerate the uncertainty of whether relationships found by these methods are the result of linguistic divergence (descent from common ancestor) or language convergence (borrowing). Much long-range comparison work has been from Russian linguists like Vladislav Illich-Svitych and Sergei Starostin. In the US, Greenberg's and Ruhlen's work has been well publicized, though it has met with little acceptance from linguists. Some well-known earlier American linguists like Morris Swadesh and Edward Sapir also pursued large-scale classifications.