The Eighteenth Century and early Nineteenth Century saw a number of novels written by political theorists
Montesquieu, Persian Letters (1721)
Montesquieu was also the author of The Spirit of the Laws
Jean-Jacques Rousseau, Julie or the New Heloise (1761) and Émile (1762)
Rousseau was also the author of The Social Contract
Benjamin Constant, Adolphe (1816)
Constant was also the author of Principles of Politics Applicable to all Governments
These are all writers in French, though Constant and Rousseau were Swiss in origin, which might or might not tell us something about why they liked to write in fiction as well as in theoretical prose. Voltaire’s Candide (1759) is maybe a related case, but not the same thing.
This trio is united by an interest in liberty and the institutions which maintain liberty. Rousseau is associated with a belief in economic equality and antique republicanism of an anti-individualistic anti-commercial kind; Constant with a preference for the most commercial and individualistic aspects of the ancient Athenian republic and a very individualistic understanding of liberty; Montesquieu might be placed between them. This is terribly crude and I would say there is more in common between them than this kind of typography suggests. In particular, Rousseau was somewhat more open to a heterogeneous modern polity based on commercial wealth, and was more individualistic in his thinking than the stereotypical readings suggest. What they all have in common is a sense that the individual is not fully at home in modern social organisation, which is why they write ‘novels’ full of natural feeling and free individuality, or at least the awareness of them and desire for them.
There was a a few decades in which major liberal or republican thinkers, in France, felt it necessary to express ideas through novelistic fictions. In the late 1790s Friedrich Schlegel related the novel as dialogue with republicanism in politics, but the practice of major theorists expressing themselves through works of literature did not last long, and does not have many clear precedents. The closest I can think of is Milton’s Paradise Lost (1667), as Milton also wrote political essays but this is not an example of a major theorist turning to fiction.
After the time I am referring to, the English poet Samuel Taylor Coleridge published On The Constitution of the Church and State (1830). Like Schlegel, in his later years he moved away from the radicalism that liberal and republican ideas represented at that time. Coleridge’s book is conservative classic which regards the state as joined with a national church as a prime expression of the nation. The liberal or republican view of the aesthetic as individualist has evolved into an organicist conservatism in which there is an aesthetic harmony of the traditional parts of the nation. However, this kind of organicist conservatism was the starting point of the political thinking of the leading liberal politician of Nineteenth Century Britain, William Ewart Gladstone. His main rival as greatest Prime Minister of late Nineteenth Century Britain was Benjamin Disraeli. Disraeli wrote organicist conservative novels like Sybil or Two Nations (1845) which is concerned with the poor in anti-democratic anti-commercial aristocratic way. As a political leader, Disraeli’s conservatism was more democratic, individualistic and commercial, and so Gladstone and Disraeli evolved in the same direction while often opposing each other on issues of the day. They were also very opposed in character and the rivalry is almost a real life novel.
The move from the literary expression of the political in Montesquieu, Rousseau and Constant seems to be a move from aesthetic individualism at odds with society to an aesthetic harmony of society. This becomes an oscillation however, in which one side of the opposition can transform into the other side.