Beginning during the pandemic, David Runciman made a series of discursive podcasts devoted to some of the great political thinkers of the past. His first book of essays based on those podcasts, Confronting Leviathan, was a perfect primer for the examination of the exercise of power, through the eyes and words of De Tocqueville and Marx and Hannah Arendt and others, in a time of state-enforced restriction of liberty.

This second collection is timely in a different way. It is loosely themed around those thinkers whose primary focus was imagining different kinds of improvements to the politics and the societies in which they lived; they each attend, in different ways, to the question, Runciman says, of “wanting to know why we find ourselves in the situation we do and how we could achieve something better”. It would be a useful volume to place at the bedsides of Keir Starmer and Rachel Reeves.

Runciman, professor of politics at Cambridge University, wears his scholarship with half a smile. He has that gift, both as a podcaster and as a writer, to illuminate abstruse and abstract ideas with human charm. He also has a journalistic sense of where the story lies. In different ways, then, the meditations here, each 20 or so pages long, on figures as distinct as Jeremy Bentham, and Rosa Luxemburg and Simone de Beauvoir are that rare kind of treat: page-turning life stories that, sentence by sentence, make you feel a little more learned than you felt before.

He begins with Rousseau, and in particular his 1755 Discourse on Inequality, the Swiss philosopher’s entry to an essay competition run by the Academy of Dijon – a sort of Enlightenment France Has Got Talent – that addressed how we ended up in a world in which “an imbecile should lead a wise man, and a handful of people should gorge themselves on superfluities while the hungry multitude goes in want of necessities”. Briskly examining Jean-Jacques’s rewind into human prehistory to explain this state of affairs, Runciman is able to collapse certain myths, not least that persistent idea that Rousseau was the “friendly” and “natural” philosopher, the first hippy, the consummate rewilder, by reminding the reader that so indifferent was he to the “artificial” and “constraining” bonds of society, that he put all his five children into a foundling home, dramatising his belief that even family ties were a “sham”, and that the individual and his relationship with nature was all that counted.

At the other “bracing” extreme from Rousseau he argues that Nietzsche, another great unraveller of human political DNA, comes at the “how the hell did we get here?” question from the diametrically opposed position: not “how did the privileged few come to dominate the many” but how did the many, through religion and democracy, come to dominate the few, the elite, the powerful, their true masters? In both cases, however, Runciman argues, their upending of received wisdom on property and propriety, on good and evil, had a forward-looking intent. It was Rousseau’s contention that we had to understand our origins in order to overturn ingrained social hierarchies. In the case of Nietzsche, in Runciman’s generous reading, the speculation on human pre-history was designed to provoke a sense of all that we might be capable of: “We can do anything.”

Between these biggest of philosophical beasts, his accounts of how the nuance and practicality of the world might be remade starts to get evermore interesting. Bentham, a figure too often reduced to his utilitarian catchphrase (and armchair-diagnosed as autistic), is brilliantly revived here; the section on Frederick Douglass, who spent his early years as an enslaved person in Maryland and became the most erudite voice of emancipation, makes you want to immediately download everything he wrote.

Runciman has the curiosity to give that kind of intellectual “rizz” to the soberest of minds. He shows that the Harvard philosopher John Rawls, author of A Theory of Justice (1971), was shaped not only by his experience of the horrors of the second world war, but by the pressing question of “what we were fighting for” - a query his book took 20 years of careful gestation to answer. That act of supremely concentrated attention is set here, as in life, against the work of Rawls’s Harvard colleague Robert Nozick, whose Anarchy, State, and Utopia (1974) has become a foundational text for the billionaire tech dreamers of Silicon Valley. Rawls, Runciman reminds you, was a reference point in the “liberal fantasy” of The West Wing, while there was a nod to Nozick in The Sopranos, when a character decides only a madman would give evidence against the mob. The future of American democracy, you may imagine, lies somewhere between those two poles.

• The History of Ideas: Equality, Justice and Revolution by David Runciman is published by Profile Books (£22). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply