Of Liberty and Necessity: The Free Will Debate in Eighteenth-Century British Philosophy (review)

Early modern historians and philosophers interested in human freedom can profitably read this book, which provides a synoptic view of the eighteenth-century British free will debate from Locke through Dugald Stewart. Scholars have not ignored the debate, but as they have tended to focus on canonical figures (Locke, Hume, and Reid), the author’s inclusion of lesser-known yet significant thinkers such as Lord Kames, Jonathan Edwards, and James Beattie is especially welcome. The main thesis of James Harris’s book is that the eighteenth-century British debate was animated by a general commitment to “experimentalism,” i.e., the view that we should be faithful to the data of our experiences of willing. Locke initiated the turn to experimentalism, but in Harris’s judgment it was Hume who first fully adopted it. Of course, Hume’s deflationary moves did nothing to slow the debate, let alone settle it, and necessitarians (Kames, Edwards, Joseph Priestley, and Alexander Crombie) continued to battle libertarians (Beattie, Reid, James Gregory, and Stewart).

An equally important theme in the book is the changing fortunes of the contrary notions of moral and physical necessity. In the beginning, only libertarians (Bramhall and Clarke) ascribed moral necessity to the motives underlying human behavior, over the objections of necessitarians (Hobbes and Collins) that physical necessity is the only sort of necessity. Later, however, necessitarians such as Edwards began utilizing the distinction between moral and physical necessity. The book seems to imply a connection between these two themes and the idea that somehow the commitment to experimentalism, which is lacking in the Hobbes-Bramhall and Collins-Clarke debates, pushed necessitarians toward the distinction between moral and physical necessity, but the nature of that connection remains obscure. In any case, the story is fundamentally one of philosophical failure because the commitment to experimentalism provided these thinkers with no leverage against questions about our freedom. Despite their new orientation, the debate remained stalled because, Harris suggests, there was “profound disagreement about what exactly it meant . . . ‘to introduce the experimental method of reasoning into moral subjects’.”

What makes this a good book are its interesting and provocative discussions of Hume and Reid. Harris sees Hume’s treatment as more revolutionary than most, arguing that it rests on a “contentious” understanding of the copy principle that all simple ideas are copies of impressions—it does not follow from my being unable to identify an idea’s aboriginal impression that the resulting idea is incoherent. And regarding Reid, Harris finds parallels between his common-sense commitments to libertarianism and the possibility of knowledge that suggest his critique of the way of ideas is inadequate without a full defense of libertarianism.

To have made this a great book, however, Harris should have engaged the secondary literature more and shown why his interpretations are preferable to the alternatives. He clearly knows the literature and has something to say about it, but his comments are buried in footnotes and tend to be passing notices of differences rather efforts to engage the contrary arguments. The biggest flaw, however, is the book’s failure to demonstrate the impact of the rise of experimentalism, a thesis that looks strained when applied to thinkers after Reid. James Gregory, for example, rejects the experimentalist’s “direct appeals to [our] consciousness” of willing for deciding the issue in favor of a priori arguments, and against the necessitarian’s conception of human agency and causation as constant conjunction. So too, Alexander Crombie defends necessitarianism by postulating that many of our motives are unconscious, contrary to Reid’s experimentalist appeals to motiveless activity. Moreover, there are several thinkers, often though not always necessaritarian (e.g., Richard Price and James Oswald in their arguments from moral responsibility), who utilize speculative theses in their analyses of the experience of willing, which makes one wonder about their commitment to experimentalism. Part of the problem is the way Harris focuses on simply laying out...