Ancient Scepticism Explained — Pyrrho, Agrippa’s Five Modes, and the Path to Inner Peace

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Introduction — The Fourth Hellenistic School

Ancient Scepticism is the fourth of the five Hellenistic philosophical schools that developed between the death of Aristotle and the rise of Christian philosophy. It shares the Hellenistic period’s characteristic concern — how to live well in conditions of uncertainty and diminished control — but addresses it in a distinctive way. Rather than offering a positive doctrine about the nature of happiness or the good life, Scepticism begins with a prior question: can we know anything at all? And its answer, carefully formulated, is: it appears that we cannot.

This lecture traces sceptical thought from its founding figure Pyrrho through the Academic Sceptics Arcesilaus and Carneades, through Agrippa’s systematic five modes, to Sextus Empiricus — the most important surviving source for the entire tradition. The thread connecting all these thinkers is a single, enduring philosophical challenge: no matter how carefully we reason or how attentively we observe, we cannot verify that our conclusions match reality. What we have is always appearances — never the things themselves.

Table of Contents

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1. What Is Scepticism? — The Problem of Definition

The word ‘scepticism’ derives from the Greek skeptikos, meaning one who inquires or examines. Sceptics examine the foundations of human belief — the grounds on which we claim to know things — and find those foundations inadequate.

But here an immediate difficulty arises — one that the lecturer explicitly flags at the outset of this lecture. Defining scepticism carelessly leads straight into self-contradiction.

The Self-Refutation Problem

The most common naive formulation of scepticism — ‘knowledge is impossible’ or ‘we cannot know anything’ — is self-refuting. If knowledge is impossible, then the claim that knowledge is impossible is itself impossible to know. The statement undermines itself before it has begun.

This is not merely an abstract logical puzzle. It reflects a genuine and deep structural difficulty: any sceptical claim that is stated as a positive truth about reality faces the same objection as every other claim about reality. If sceptics cannot trust the senses or reason to reveal reality, they equally cannot trust them to reveal that ‘knowledge is impossible.’ The sceptical conclusion, stated dogmatically, is just one more unjustified claim about how things are.

Appearance Language — The Sceptical Solution

Genuine sceptics are therefore extremely careful about how they speak. They use appearance language consistently — language that reports only how things seem, not how they are. This precision is the logical heart of the sceptical position, not a stylistic flourish.

	Dogmatic language (what sceptics avoid)	Sceptical appearance language (what sceptics use)
Statement about colour	The apple is red. (A claim about reality — what the apple IS.)	The apple appears red to me. / The apple looks red to me. (A claim about appearance only — how it seems.)
Statement about sensation	The water is hot. (A claim about reality — the water’s actual temperature.)	The water feels hot to me. (A claim about how I experience it — not what it actually is.)
Statement about knowledge	Knowledge is impossible. (A claim about reality — and a self-refuting one: if nothing can be known, how do you know this?)	It appears to me that knowledge may not be possible. (An appearance claim — not a dogmatic assertion, and therefore not self-refuting.)
Statement about scepticism itself	Scepticism is true. (A dogmatic claim about the truth of scepticism — which contradicts its own method.)	It appears that scepticism may be the most reasonable approach. (An appearance claim — the sceptic applies the same method to their own position.)
The underlying principle	Every claim about reality presupposes a way of verifying it — which sceptics argue we do not have.	Every claim is limited to ‘how things appear from within my perspective’ — which is all we genuinely have access to.

Notice that this precision extends even to scepticism itself. A rigorous sceptic does not say ‘scepticism is true’ — that would be a claim about reality. They say ‘it appears to us that scepticism may be the most reasonable approach.’ They apply the same method to their own position that they apply to everything else: no final verdict, only reported appearances.

Sceptics do not say ‘the apple is red’ — they say ‘the apple appears red to me.’ They do not say ‘the water is hot’ — they say ‘the water feels hot to me.’ The shift is systematic: everything is expressed as appearance, never as reality. And this applies equally to scepticism about knowledge itself: not ‘knowledge is impossible’ but ‘it appears that knowledge may not be possible.’

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2. Pyrrho of Elis — The Founding Figure

Pyrrho of Elis (c. 360–270 BC) is the philosopher most associated with the founding of the sceptical tradition, so much so that ancient scepticism is often called Pyrrhonism. He left no written works, and our knowledge of his views comes through later sources. But his central argument has proven extraordinarily durable.

Why the Senses Cannot Give Us Knowledge

The blue lens analogy: Imagine you are wearing glasses with a blue-tinted lens. Everything you see appears with a blue cast. To verify whether things are actually blue or only appear blue through the lens, you need to do something straightforward: remove the lens and compare. Look at the same thing through the lens, then without it. Compare the two views. This gives you a way to distinguish ‘how things appear through the lens’ from ‘how things actually are.’ But now consider your naked eyes. You see a book in front of you. How would you verify whether the book actually looks the way it appears to your eyes — without using your eyes? You cannot remove your eyes and set them aside for comparison. There is no ‘lens-free’ view of reality available to you. You are permanently inside your own senses. Therefore you can know how things appear through your senses but you cannot know whether appearances match reality.

This is Pyrrho’s fundamental point. We are never outside our sensory apparatus. Our senses do not give us the world as it is; they give us the world as it appears through the specific sensory organs we happen to possess. And since we cannot step outside those organs to compare, the question of whether appearances match reality cannot be answered.

Why Reason Also Falls Short

Pyrrho applies the same critique to rational argument. For any argument presented in favour of a conclusion, a counterargument can be constructed against it. From Thales to Aristotle — and now from the Epicureans to the Stoics — every philosopher has offered their account of reality using reason, and every account has been challenged by others using reason equally carefully. The persistence of disagreement across centuries of careful reasoning is itself evidence that reason alone cannot settle the question of truth.

Pyrrho’s practical conclusion was straightforward: since we cannot establish certainty through either senses or reason, we should stop trying to force definitive answers onto questions that resist them. Spend less time on theories and more time on life. Things are indeterminable — no fixed, certain description can be attached to them. This indeterminability invites us to suspend judgment, and suspension of judgment brings inner freedom.

Pyrrho and the Indian Connection

Christopher Beckwith, in his book ‘Greek Buddha,’ argues that Pyrrho accompanied Alexander the Great’s expedition to India and there encountered Buddhist monks — possibly Madhyamika scholars. If accurate, this would suggest a connection between Pyrrho’s concept of ‘indeterminability’ (things having no fixed nature that can be definitively described) and the Madhyamika concept of śūnyatā (emptiness — the absence of inherent, fixed nature in things). This remains a scholarly hypothesis, not a settled historical conclusion, and is presented here as a possibility worth noting rather than an established fact.

A Practical Philosophy

Pyrrho was not primarily interested in metaphysical theory for its own sake. His scepticism was in service of a practical goal: living well. He observed that certainty-seekers are perpetually restless, and that those who believe they have found certainty are driven by their beliefs in ways that create suffering. The alternative was to suspend all judgment about reality — and discover that without a belief system to defend or pursue, a kind of deep freedom and peace becomes available.

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3. Scepticism in Plato’s Academy

One of the more surprising episodes in the history of philosophy is the transformation of Plato’s Academy — founded as a direct response to the Sophists’ relativism — into a stronghold of scepticism. This transformation was engineered principally by Arcesilaus and then extended by Carneades.

Arcesilaus — The Sceptical Reading of Plato

Arcesilaus (~316–241 BC) became head of Plato’s Academy and redirected its philosophical programme toward scepticism. His justification for this direction was subtle: he argued that Socrates and Plato, read carefully, were themselves not dogmatists.

• Socrates repeatedly declared: ‘I know nothing.’ This was not false modesty — it was a genuine philosophical position that the examination of alleged knowledge consistently revealed ignorance.
• The Socratic dialogues never reach settled conclusions. Every dialogue ends with a question or an unresolved tension, not a definitive answer. This structure itself suggests that philosophy is an ongoing inquiry, not a doctrine.
• Plato himself, in the Timaeus, described his account of physical reality as ‘a likely story’ — not a certain truth but a probable account. This was Plato’s own admission that certainty about physical reality is beyond reach.

By selectively highlighting these aspects of the Socratic and Platonic tradition, Arcesilaus could present scepticism not as a departure from the Academy’s heritage but as its most faithful continuation. Whether this was an accurate reading of Plato is another question — but it was rhetorically and philosophically significant.

Carneades — Probability and the Two-Faced Arguments

Carneades (~214–129 BC) was among the most brilliant philosophers of his era. He became famous in Rome for his demonstrations of what might be called the ‘two-faced argument.’

The two-faced arguments: Carneades would give a public lecture on day one arguing passionately and with great skill for a particular position — justice, say, or the gods — convincing his audience entirely. On day two he would lecture with equal passion and equal skill for the opposite position, again convincing the same audience. The effect was to show, vividly, that reason is an instrument of persuasion rather than a detector of truth. If reason could construct equally compelling arguments on both sides of any question, it could not be the means by which we reach certainty.

Carneades’ Answer to the Stoic Objection

The Stoics raised what seemed to be a decisive objection to scepticism: if nothing can be known with certainty, action becomes impossible. Every action requires a judgment — this path is safer, this food is edible, this person is trustworthy. If all such judgments are unjustified, life grinds to a halt.

Carneades conceded the point but argued that the Stoics had confused certainty with probability. Certainty is not required for action. We act on probability every day — and we always have.

The fruit example: You pick up a fruit in the market to buy. You cannot open it to see whether it is good inside. But from its external appearance — its colour, firmness, smell — you can form a probability judgment: this fruit is probably good. That probability judgment is sufficient to make the purchase. You do not need certainty to buy fruit; you need a reasonable probability assessment. Life is full of such assessments, and they serve us well enough.

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4. Carneades’ Theory of Probability — Cross-Checking Appearances

Carneades developed a more sophisticated philosophical account of how probability works in practice — an account that anticipates important ideas in modern epistemology.

When we experience any object or event, we do not receive a single piece of sense data. We receive many different types of sensory information simultaneously, all about the same thing. And these different data types can be compared with each other.

The fire example: Standing before a fire, your senses simultaneously provide you with: the colour and light of the flames (sight); the heat radiating from it (touch); the crackling and popping sounds it makes (hearing); the smoke you can see rising (sight); the specific smell of burning material (smell). None of these can be compared directly with ‘actual fire’ — you have no unmediated access to fire-as-it-is-in-itself. But you can compare all these different types of appearance data with each other. Do they form a consistent picture? Yes — the colour, heat, sound, smoke, and smell all cohere in the way you would expect from a fire. This consistency across multiple independent data sources gives you grounds for treating your experience as probably genuine.

The doctor’s diagnosis: A doctor diagnosing fever does not rely on a single measurement. He checks temperature. He checks pulse. He examines the eyes. He asks about headache, fatigue, and appetite. Each of these is a separate type of data, drawn from different sources. If they are all consistent — elevated temperature, elevated pulse, flushed eyes, reported headache and fatigue, reduced appetite — this consistency across multiple independent indicators gives reasonable grounds for the diagnosis. The doctor may still be wrong. But the diagnosis is not arbitrary — it is grounded in the mutual consistency of diverse data. This is how probability justifies action even in the absence of certainty.

The logical structure of Carneades’ method is: since appearances cannot be compared with reality directly (we have no unmediated access to reality), we compare the different dimensions of appearance with each other. Consistent appearances across multiple independent sensory channels give us a higher probability that our overall experience is reliable — without ever achieving certainty.

This approach was rejected by more rigorous sceptics who argued that even probability involves a judgment about appearances, and is therefore unjustified by strict sceptical standards. But Carneades’ insight proved influential far beyond the ancient world — it anticipates Bayesian reasoning, coherentism in epistemology, and scientific method’s reliance on convergent evidence.

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5. Agrippa’s Five Modes — A Systematic Sceptical Framework

After Carneades, the philosopher Agrippa systematised the sceptical critique into five formal modes — five independent arguments, each showing that no belief can be conclusively justified. Together they are comprehensive: they address disagreement among believers, the logical structure of justification, the variability of perception, the status of starting assumptions, and the circularity of some proofs.

#	Mode	The argument	Illustration
1	Disagreement (Diaphonia)	On any topic — ethical, scientific, or philosophical — no universal agreement is ever reached; different people and different cultures have always disagreed.	Moral values: some cultures value individual rights; others value collective harmony. Scientific theories: Thales said water; Democritus said atoms; Aristotle said substance and form. If truth were knowable, we would expect convergence — but we find endless disagreement instead.
2	Infinite Regress (Eis apeiron)	Every belief requires a justification. That justification requires its own justification. The chain goes back forever with no resting point.	Why believe X? Because of reason A. Why believe A? Because of reason B. Why believe B? Because of C. The chain never reaches bedrock — there is no self-justifying foundation that stops the regress.
3	Relativity (To pros ti)	All perception and judgment depends on the observer, their condition, their culture, their emotional state, and their context. No ‘view from nowhere’ is available.	Rain: excellent news for the farmer whose crops need water; terrible news for the potter whose clay products will be ruined. Honey: tastes sweet to a healthy person; tastes unpleasant to someone with a fever. Same event, same substance — opposite experiences.
4	Hypothesis (Hypolēpsis)	Reasoning systems require starting assumptions (‘axioms’ or ‘first principles’). These are typically declared ‘self-evident’ — needing no justification. But sceptics argue nothing is truly self-evident; every starting point is arbitrary.	‘All humans desire happiness’ — taken as a self-evident premise in many ethical systems. But is it true of everyone? Some desire power; some desire status; some desire knowledge above happiness. What makes it ‘self-evident,’ and on what basis is that self-evidence established?
5	Circularity (Diallelos)	Some arguments prove their conclusion by secretly assuming it in the premises — the proof goes in a circle rather than moving forward.	‘The Bible is true because God wrote it. God exists because the Bible says so.’ The conclusion (‘the Bible is true / God exists’) is already hidden in the premises — neither claim establishes the other independently.

The Combined Force of the Five Modes

Considered together, the five modes leave no obvious escape route for the dogmatist — the person who claims to know something with certainty.

• If you try to justify your belief by pointing to the agreement of others, you run into disagreement — others disagree with equal force.
• If you try to justify it by argument, you face infinite regress — the argument’s premises need their own justification.
• If you try to ground it in direct experience, you face relativity — experience varies with the observer.
• If you try to stop the regress by declaring certain starting points self-evident, you face the hypothesis problem — nothing is genuinely self-evident.
• If your proof circles back to what you were trying to establish, you face circularity — you have proved nothing.

The five modes together constitute what modern epistemologists sometimes call ‘Agrippa’s Trilemma‘ — the observation that any attempt to justify a belief leads to one of three unpalatable outcomes: infinite regress, circularity, or arbitrary foundations. This problem is not merely historical; it remains a central unresolved issue in contemporary epistemology.

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6. Sextus Empiricus — The Great Systematiser

Sextus Empiricus (c. 160–210 AD) lived approximately five centuries after Pyrrho. He was not primarily an original philosopher but rather the most important preserver and systematiser of the sceptical tradition. His Outlines of Pyrrhonism (Pyrrhōneioi Hypotypōseis) is the single most reliable surviving source for ancient scepticism, recording the views of earlier thinkers with great care and organising them into a coherent framework.

The Precision of His Method

What makes Sextus Empiricus philosophically distinctive is his extreme care with language — the quality the lecturer singles out as particularly admirable. He is acutely aware of the self-refutation problem and works hard to avoid it at every step.

• He does not say ‘knowledge is impossible’ — this would be a positive claim about reality, and therefore a form of the dogmatism he is opposing.
• He says instead: ‘we have not yet found the truth, but we are still searching’ — a formulation that is honest about the current state of inquiry without claiming certainty about whether truth is findable.
• He applies appearance language consistently throughout his work, modelling in practice the very precision he advocates in theory.

The Criterion Problem

One of Sextus Empiricus’s clearest contributions is his formulation of what is called the criterion problem. The problem arises directly from the diversity of philosophical views across the history of philosophy.

From Thales to Aristotle, and from Epicurus to the Stoics, philosophers have given radically different answers to the most fundamental questions: what is reality made of? What is the highest good? What is the nature of the soul? Each claims to have the truth. But these answers contradict each other. To decide which is correct, we need a standard — a criterion of truth.

But before we can use a criterion to evaluate philosophical claims, we need to know that the criterion itself is correct. And to know that the criterion is correct, we need another criterion to evaluate it. Which leads to yet another criterion, and so on without end.

The measuring tool analogy: To measure whether a table is three feet wide, you use a ruler. But to trust the ruler’s measurement, you need to know the ruler is correctly calibrated. To verify the ruler’s calibration, you compare it with a standard metre or another verified measuring instrument. And to trust that instrument, you need to verify it too. The regress is clear: any measuring tool must itself be verified, which requires another measuring tool, which requires another. At some point you reach a tool you simply assume is correct — but that assumption is not itself verified. The same logic applies to any criterion of truth: before using it, you must verify it is reliable; and to verify it, you need another criterion; and so on without end.

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7. Epochē and Ataraxia — How Scepticism Leads to Happiness

Ancient scepticism is not merely a theoretical position about the limits of knowledge. Like all the Hellenistic schools, it is fundamentally a practical philosophy — a way of living. And like Epicureanism and Stoicism, it offers a path to ataraxia — inner peace and freedom from disturbance. But the sceptical path to this state is unique.

Two Types of Disturbed People

	The Truth-Seeker	The Truth-Claimer	The Sceptic
Core belief	Truth exists and I can find it — but I have not found it yet	I have found the truth; I know what is good and what is bad	I do not know whether truth is findable, and I make no claim either way
Relationship to ‘good’	Pursues what they hope will turn out to be good, once truth is found	Relentlessly pursues what they believe is good	Makes no pursuit based on knowledge of what is good — acts on appearances only
Relationship to ‘bad’	Anxious about what might turn out to be bad	Actively flees what they believe is bad	Makes no avoidance based on knowledge of what is bad
Mental state	Perpetual restlessness — the search is never complete; satisfaction is always deferred	Perpetually driven — belief system pulls them toward and away from things; creates ongoing desire and aversion	Neither restless nor driven — no theory to be anxious about; no belief to defend
Result	Unhappy — the gap between ‘truth not yet found’ and ‘truth needed’ creates chronic dissatisfaction	Unhappy — the belief system creates desire, aversion, and the suffering these produce	Inner peace (ataraxia) — freedom from the disturbance of both seeking and claiming

What this table reveals is that disturbance — chronic anxiety, restlessness, driven desire and aversion — is not a product of external circumstances. It is a product of belief. The truth-seeker is disturbed by the gap between the truth they believe exists and the truth they have not found. The truth-claimer is disturbed by the demand their beliefs place on them — pursue this, avoid that, defend this position, attack that one.

Epochē — Suspension of Judgment

The sceptical response is epochē — suspension of judgment. Neither assert nor deny; neither pursue on the basis of knowledge nor avoid on the basis of knowledge. Observe what appears; report appearances; act on probability when action is required; but make no final claim about what is really the case.

Epochē is not intellectual defeat or resignation. It is intellectual honesty — the honest acknowledgment that, after centuries of philosophical inquiry, certainty has not been achieved and the means to achieve it have not been established. The sceptic is not someone who has given up; they are someone who is honest about what has and has not been found.

This suspension of judgment produces its own form of happiness. Without a belief system to defend, there is nothing to protect. Without a theory of the good driving pursuit of specific outcomes, there is no chronic desire. Without a theory of the bad driving avoidance of specific circumstances, there is no chronic fear. The mind, released from the pressure of its own convictions, settles into a natural, unforced equilibrium — ataraxia.

This is similar in outward appearance to the Stoic apatheia and the Epicurean ataraxia, but the route to it is entirely different. The Stoic reaches equanimity by correctly understanding the logos and eliminating false judgments about external things. The Epicurean reaches it by eliminating false beliefs about gods and death. The sceptic reaches it by eliminating all fixed beliefs — not correcting them, but suspending them entirely.

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8. Scepticism as Philosophy’s Ghost

The lecturer closes with an observation that deserves to be treated as a philosophical claim in its own right: scepticism is philosophy’s ghost.

Throughout the history of philosophy, scepticism has repeatedly been challenged and apparently refuted. Plato’s Forms were meant to provide objects of genuine knowledge, immune to the variability of sense experience. Descartes thought he had defeated scepticism with the cogito. Kant thought he had set epistemology on secure foundations. Each generation has believed it found the answer — and each generation has found scepticism returning in a new form.

The reason is not that sceptics are merely being difficult. It is that they are pressing on a genuine problem: the gap between how things appear and how things are, the difficulty of justifying our starting assumptions, the inability to verify our own cognitive instruments using those same instruments. These are not problems that philosophical ingenuity has been able to dissolve — they have been reformulated, redirected, and at times obscured, but they have not been resolved.

Scepticism’s philosophical value:  Scepticism keeps philosophy honest. It is the persistent internal critic that prevents any system of thought from hardening into dogmatism. If we are not self-critical — if we do not regularly examine the foundations of what we believe we know — we become dogmatic: we accept our starting assumptions without scrutiny, our conclusions without examination, our methods without question. Scepticism is the philosophical discipline that makes that kind of self-examination inevitable.

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Conclusion

Ancient scepticism is the most philosophically careful of the Hellenistic schools. It makes no positive claims about the nature of reality, the structure of the cosmos, or the definition of the good. It does something harder and, in its own way, more honest: it examines the foundations of all such claims and finds those foundations impossible to secure. The lens analogy, the criterion problem, and Agrippa’s five modes are not rhetorical flourishes — they are serious philosophical arguments that have not been definitively answered in over two thousand years of subsequent philosophy.

The sceptical path to happiness — suspension of judgment leading to inner peace — is therefore not a path of intellectual laziness but of intellectual honesty. The sceptic is not someone who refuses to think; they are someone who has thought very carefully indeed, found no secure foundation, and drawn the appropriate practical conclusion: let go of the need for certainty, and discover that a settled, undisturbed life is available without it.

Scepticism will reappear throughout the subsequent history of Western philosophy — in Descartes’ method of doubt, in Hume’s scepticism about causation and induction, in Kant’s critical philosophy, and in contemporary debates about the regress problem in epistemology. It is not a school that was resolved and set aside. It is a question that philosophy is still working through.

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Frequently Asked Questions

Why can’t sceptics simply say ‘knowledge is impossible’?

Because that formulation is self-refuting — it destroys itself before it can stand. If knowledge is genuinely impossible, then the claim that ‘knowledge is impossible’ is itself a piece of knowledge — which means knowledge is possible after all, contradicting the very claim. The statement undermines its own foundations. This is why rigorous sceptics from Pyrrho through Sextus Empiricus are so careful with language. They do not make positive claims about what is or is not the case in reality. Instead they use appearance language: ‘it appears to us that certainty may not be achievable’; ‘we have not yet found the truth, but we continue to search.’ These formulations report how things seem without claiming to know how they are — and therefore they are not vulnerable to the self-refutation objection.

How does Pyrrho’s argument about the senses actually work?

Pyrrho’s argument begins with a simple observation: to verify that any instrument is working correctly, you must be able to compare its output with something independent of it. If you suspect your blue-tinted glasses are distorting what you see, you can remove them and compare: how does the object look through the glasses, and how does it look without them? The comparison gives you a way to assess whether the glasses are introducing distortion. But you cannot do the same thing with your own senses. To verify whether your eyes are showing you things accurately, you would need to see the same object without your eyes — which is obviously impossible. You are permanently inside your own sensory apparatus with no exit. Therefore, while the senses provide abundant information about how the world appears, they cannot provide certainty about whether those appearances match reality. The same logic applies to the other senses: there is no sensory experience of ‘things as they are in themselves,’ only of ‘things as they appear through our particular sensory organs.’

How does Carneades’ probability approach differ from ordinary scepticism?

Carneades accepts the core sceptical claim that certainty is unavailable through either senses or reason. But he responds to the Stoic objection — that without certainty, action is impossible — by pointing out that certainty has never been required for action. We act on probability all the time. His specific contribution is a theory of how probability is established in practice: by cross-checking multiple independent types of sense data about the same object. If your visual, tactile, auditory, and olfactory data about a fire are all mutually consistent — if the colour, heat, sound, smoke, and smell form a coherent picture — this consistency gives grounds for treating your experience as probably reliable. This is how a doctor builds up a diagnosis from multiple consistent symptoms, and how we judge fruit by its external qualities before purchasing it. Carneades is not claiming certainty; he is claiming that consistent appearances provide sufficient grounds for reasonable action. This was rejected by more rigorous sceptics, but it anticipates important ideas in modern scientific reasoning and Bayesian epistemology.

What are Agrippa’s five modes, and why are they important?

Agrippa’s five modes are five independent arguments, each showing that no belief can be conclusively justified. Disagreement: no topic produces universal agreement, which shows that certainty is not achievable. Infinite regress: any justification for a belief requires its own justification, producing an endless chain with no resting point. Relativity: all perception varies with the observer, their condition, and their context, so no single perspective can be declared the correct one. Hypothesis: every reasoning system must start somewhere, but any starting point can be challenged — nothing is truly self-evident. Circularity: some arguments secretly assume their conclusion in their premises, proving nothing. Together these five modes are sometimes called ‘Agrippa’s Trilemma’ in modern epistemology, where the problem is restated as: any attempt to justify a belief leads to regress, circularity, or arbitrary assumption. This trilemma is a live issue in contemporary philosophy — it has not been definitively resolved, which is one reason why scepticism keeps returning.

How does sceptical epochē lead to happiness?

The sceptical route to happiness rests on a diagnosis of what causes human unhappiness. Two types of people are chronically disturbed: those who believe truth exists and are restlessly searching for it without success, and those who believe they have found the truth and are relentlessly driven by their beliefs — pursuing what they call ‘good,’ avoiding what they call ‘bad.’ Both are disturbed by their belief systems: the first by the gap between what they believe should be known and what they actually know; the second by the demands their beliefs place on them. The sceptic escapes both forms of disturbance through epochē — suspension of judgment. Without a fixed belief about what is good, there is no chronic pursuit. Without a fixed belief about what is bad, there is no chronic avoidance. The mind, freed from the pressure of its own convictions, settles into ataraxia — the same deep inner peace sought by Epicureans and Stoics, but reached by a different path. The sceptic does not achieve peace by correctly understanding the world; they achieve it by releasing the need to understand the world with certainty.

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