When Leibniz writes to Caroline to express his concern over the dangerous thinking in England he specifically names “Locke and his followers” and “Newton and his followers.” But who exactly were Locke’s “followers,” and why don’t we talk about them more in the context of the Leibniz-Clarke correspondence?
First, some context. Sophie Charlotte and her husband, King Frederick I of Prussia, were (for a while) guardians to Princess Caroline of Ansbach. Sophie Charlotte frequently hosted Leibniz in Berlin and elsewhere (while Leibniz was supposed to be working on his history of the Brunswick family), and it is in her court that he met Caroline and eventually became her tutor. Caroline would become the central (but hidden) figure in the Leibniz-Clarke correspondence, passing the letters between them with her own observations stated in accompanying letters. In addition to the broader public and the official correspondent, Caroline is the unstated audience for both Leibniz and Clarke. (See Meli 1999 for more on Caroline’s role in the Leibniz-Clarke correspondence.)
Leibniz’s initial letter to Caroline (printed as the first letter in the Leibniz-Clarke correspondence) is an attempt to keep Caroline from straying from his views and toward the (to Leibniz) dangerous views in England. He specifically mentions “Locke and his followers” and “Newton and his followers” in his opening salvo.
Because Clarke, who takes up the cause of English “natural religion,” is clearly a member of “Newton and his followers” and defends (half-heartedly) Newton’s use of sensorium and defends (very well) Newton’s “very odd opinion concerning God’s workmanship,” scholarship has focused on the letters as a debate between Leibniz on the one side and Newton-Clarke (with various weightings assigned to Newton and Clarke as author) on the other. Partly this is because Clarke is clearly opposed to the position ascribed to “Locke and his followers” that they “aren’t sure whether the soul is material and naturally perishable.” In asking who “Locke and his followers” are, we can look to those who think the soul is “material and naturally perishable.”
The debate about a “naturally perishable” soul focused in early eighteenth century Britain on Henry Dodwell, who had argued that the soul only became immortal at baptism. Clarke opposes this view in a typically public letter. Anthony Collins responds, and the two men’s subsequent correspondence (1707-1708) on the immateriality and natural immortality of the soul is a fascinating example of a substance dualist (who unlike Cartesian dualists is open to the soul being extended) and someone working towards an emergentist view long before such views became popular. Collins holds the sort of view that Leibniz sees as following from Locke’s openness to thinking matter in the later editions of the Essay Concerning Human Understanding, while Clarke defends a thinking, immaterial soul. Leibniz is aware of Dodwell as early as 1706, due perhaps to his primary British correspondent Thomas Burnett. Dodwell, then, is the first candidate for “Locke and his followers,” with Collins worth consideration, as well.
The debate between Clarke and Leibniz quickly focuses on Leibniz’s objections to Newton and Clarke rather than on the thinking matter views entertained by Locke and Collins because Clarke is the clear opponent of both Dodwell and Collins. This is part of why, I think, we think today of the Leibniz-Clarke correspondence as about Leibniz’s problems with Newtonian natural philosophy and Clarkean natural theology rather than with post-Lockean concerns about whether all souls are immortal. Because it was Clarke who, at Caroline’s request, answered Leibniz’s charge, the Leibniz-Clarke correspondence focuses on the immortality question only insofar as it is connected to questions like the nature of the sensorium and God’s relationship to space (e.g., as a world-soul).