Henrik Lagerlund, Skepticism in Philosophy: A Comprehensive, Historical Introduction.
Routledge, 2020. 254pp. Paperback: £34.99. ISBN: 9781138555563.

There is a certain kind of philosopher—usually tenured, always convinced—who treats scepticism as a disease to be cured. For these people, Sextus Empiricus is a problem to be solved, not a man to be understood. Truth, for them, is a hill worth dying on, preferably surrounded by footnotes. And yet, for those of us who have read the Greeks with our eyes open, and lived among the moderns with our noses unblocked, scepticism feels less like a pathology and more like a very basic precaution—like not drinking from a puddle just because someone in robes says it’s holy.

Henrik Lagerlund’s Skepticism in Philosophy is a pleasantly honest attempt to treat the history of philosophical doubt with something like respect. This book is marketed as a general historical introduction, and it serves that purpose well. But it does more than walk readers through two millennia of anti-certainty; it questions the traditional narrative in useful ways, rescuing important thinkers from neglect and showing that the cracks in philosophy’s foundations go deeper than most are willing to admit.

Lagerlund opens with the usual beginning: Sextus Empiricus, the second-century Greek physician whose writings form the backbone of what is now called Pyrrhonian scepticism. Unlike the caricature I’ve seen in some of the basic histories, Sextus was not a shrill relativist or a confused nihilist. He did not deny the possibility of truth. He denied our ability to claim it. This distinction—between truth’s existence and our access to it—is the insight that has gone missing in almost every popular treatment of scepticism since Augustine turned it into a problem for theologians.

What made Sextus dangerous then, and still intolerable now, was not his rejection of knowledge per se, but his ability to dismantle it wherever it was claimed. His method was simple: for every argument, provide a counterargument of equal strength. For every assertion, show the possibility of its opposite. His goal was not refutation but what he called epoche—the suspension of judgement. And, in a move that continues to baffle the faithful, he claimed this suspension led not to despair but to tranquillity (ataraxia).

Lagerlund is aware of the incredulity this provokes. What kind of lunatic, after all, finds peace by admitting he doesn’t know anything? But, as the book makes clear, Sextus did not reject practical life. He ate when hungry, slept when tired, and walked around like any other man. What he didn’t do was pretend to know what lay beyond appearances. He lived by habit, not dogma. In other words, he lived better than most of us.

From here, the book moves chronologically through scepticism’s long and often interrupted history. It challenges the view—pushed most famously by Richard Popkin—that Sextus Empiricus disappeared entirely from the West until Montaigne rediscovered him in the sixteenth century. Lagerlund grants that sceptical concerns went quiet during the Aristotelian hegemony of the thirteenth century. But he points out that a complete Latin translation of the Outlines of Pyrrhonism was made before 1300. The torch of doubt, in other words, may have flickered, but it was not extinguished.

This sets up one of the book’s main strengths: its reassessment of the medieval period. Where most histories rush from the Stoics to Descartes with little more than a shrug at Scholasticism, Lagerlund pays serious attention to neglected figures like John of Salisbury, Nicholas of Autrecourt, and even Al-Ghazālī, all of whom anticipated arguments about causality that we normally credit to Hume. When Autrecourt says there is no necessary connection between cause and effect, he’s not just warming up for Scottish Enlightenment seminars. He is saying, with admirable clarity, that the world gives us impressions, not explanations.

It is on Montaigne that Lagerlund becomes more cautious. He grants that Montaigne was the first major thinker of the early modern period to grasp the implications of Sextus’s work. But he argues, rather oddly, that Montaigne is not really a sceptic, calling his conclusion “one of pessimism more than scepticism.” This strikes me as wrong on two levels. First, Montaigne was not especially pessimistic. He was amused, he was sardonic—but not despairing. Second, his adoption of the Pyrrhonian motto epokhō (I abstain), which he had engraved on a medallion along with his age—43, in 1576—suggests something more than a passing flirtation. Montaigne read Sextus and recognised the trap: to demand certainty in an uncertain world is to guarantee anxiety. Better, he thought, to live freely with uncertainty than become a slave to invented convictions.

Where Sextus claimed that suspending belief led to peace, Montaigne held that relaxing one’s grip on certainty allowed room for life to be lived. Knowledge, he said, is fine—but not worth worshipping. “Those who despise it give evidence of their stupidity,” he wrote, “but yet I do not set its value at that extreme measure that some attribute to it.” That, in a single sentence, is a better education than three years of analytic epistemology.

Lagerlund also brings in non-Western parallels, most notably Chuang Tzu, the fourth-century BC Chinese philosopher whose butterfly dream is now philosophy’s most charming entry into radical doubt: the story of a man who dreamed he was a butterfly, and was unsure on waking if he was a man who had dreamed he was a butterfly, or a butterfly now dreaming he was a man. Chuang Tzu, like Sextus, was interested less in metaphysical truth than in the practical consequences of pretending we possess it. He argued that we must act, even while acknowledging that our perceptions may be dreams. Unlike Sextus, however, he did not claim that this insight brings peace. His conclusions were more modest: we must choose, knowing we may be wrong.

That tension—between necessary action and unavoidable ignorance—is at the heart of all honest philosophy. And it’s the reason why so many modern philosophers are dishonest.

From Montaigne, Lagerlund proceeds to the usual suspects: Descartes, Hume, Bayle, Kant, Reid. The treatment is brisk but fair. Descartes, we are reminded, borrowed sceptical methods to build a fortress of certainty. He doubted everything to establish something indubitable. Hume, by contrast, saw no point in pretending this was possible. He recognised that human behaviour rests on habit, not on rational insight. We believe in causation not because we can justify it, but because we’re wired to expect it. The sun rose yesterday, and we assume it will tomorrow. That’s not logic. It’s psychology.

Bayle, one of the most underrated thinkers in the tradition, argued that scepticism is not a threat to science, which deals in probabilities, but a threat to religion, which demands certainty. He thought scepticism liberated the mind while leaving ordinary life untouched. Lagerlund gives him the attention he deserves—something few histories of philosophy manage.

With Thomas Reid, we enter the stage of counter-attack. Reid’s argument is simple: scepticism contradicts common sense. Of course there is a world. Of course I have hands. This line of thought culminates in G.E. Moore’s famous gesture of holding up both hands and saying, “Here is one hand, here is another.” That, apparently, is supposed to settle the matter.

Wittgenstein was not impressed. He wrote that Moore was fighting on the wrong battlefield. Scepticism, he argued, does not arise from denying common sense but from the misuse of language. “There is no common-sense answer to a philosophical problem,” he wrote. “You cure the philosopher by dissolving the temptation to pose such questions.” What looks like doubt is often a confusion of categories. The sceptic isn’t saying, “I don’t know if I have hands.” He’s saying, “I don’t see how I could justify that belief in a way that defeats every possible counterargument.” The former is madness. The latter is philosophy.

Lagerlund traces this insight through to more recent thinkers like Kripke and Barry Stroud, before veering into slightly more dubious territory. He is a political leftist, and his efforts to deny that scepticism about the environmentalist claims is honest doubt are an embarrassment. These parts should have been cut, or at least confined to a footnote. Including them in the main body of the text risks harming the long range value of the book.

If I have a final criticism of the book, it is this: it still plays the game of treating scepticism as a challenge to be answered. It is not. It is a position—a lived posture, not a puzzle. Pyrrhonian scepticism is not the claim that we should doubt. It is the claim that we should neither affirm nor deny. We should attend to the world without making final claims about it. That posture, once adopted, cannot be argued away. It can only be abandoned, either through cowardice or fatigue.

Lagerlund’s history, however, is excellent. It is well-written and lucid. It introduces important figures neglected by other histories. And it reminds us that philosophy’s most persistent question has never been “What is true?” but “How can you be so sure?”

For those already committed to scepticism, this book is a useful primer. For those still under the illusion that Plato, Descartes, or Kant ever solved anything, it may be the first step towards recovery.