Plutarch's dialogue defending the Academy by arguing that Stoic doctrine, not Academic skepticism, actually violates humanity's common conceptions.
De Communibus Notitiis Adversus Stoicos ("On the Common Conceptions, Against the Stoics") is one of Plutarch's polemical philosophical essays, cast as a dialogue in which the character Diadoumenus arrives shaken after an encounter with Stoic critics of the Academy, and Lamprias sets out to reverse the charge. The Stoics had accused Academic skeptics of being 'destroyers' who philosophize contrary to koinai ennoiai, the common notions or basic conceptions shared by all human beings simply by virtue of having minds and senses. Plutarch's speaker turns the argument around: it is Chrysippus and the Stoa, he insists, who trample on common conceptions at every turn, while the Academy's suspension of judgment leaves ordinary belief undisturbed.
The bulk of the essay is a running catalogue of Stoic paradoxes measured against ordinary intuition. Plutarch presses on the Stoic claim that only virtue is good and only vice bad, so that mutilation, disease, and pain are technically 'indifferent' even though nature supposedly drives us away from them; he mocks the notion that a wise man will die for great matters yet also owes solemn praise to someone who bravely endured a fly bite. He then moves into Stoic physics: the doctrine that virtues, vices, arts, and even passions are literally bodies, indeed rational living creatures inhabiting the single point that is the soul, so that each person becomes a menagerie of hostile creatures. He hammers Chrysippus's account of night, day, and time as bodies, and closes by attacking the Stoic theory of matter, elements, and qualities as internally inconsistent, unable to say coherently what a 'simple' element or a substance 'without quality' could actually be.
The essay matters as a rare extended window into Hellenistic philosophical combat over epistemology and physics, preserving Chrysippus quotations and Stoic technical vocabulary (prolepsis, koinai ennoiai, pneuma) that would otherwise be lost, while showing a committed Academic skeptic wielding reductio ad absurdum as his chief weapon against Stoic dogmatism.
“It is natural enough, Diadoumenus, that you should not much mind if people think that you philosophize contrary to the common conceptions, since you openly profess also to look down on the senses”
— De Communibus Notitiis Adversus Stoicos · read this chapter →
“they accused the older members with real anger, calling them sophists and destroyers of the doctrines of philosophy who walk the straight road”
— De Communibus Notitiis Adversus Stoicos · read this chapter →
“a man bravely endured the bite of a fly, and prudently refrained from an old woman near death”
— De Communibus Notitiis Adversus Stoicos · read this chapter →
“to declare that each of us is a park, or a pen, or a wooden horse”
— De Communibus Notitiis Adversus Stoicos · read this chapter →
“As for the four bodies — earth, water, air, and fire — which they call the primary elements, I do not know how they make some of them simple and pure and others composite and mixed”
— De Communibus Notitiis Adversus Stoicos · read this chapter →
It is Plutarch's dialogue defending the Academic skeptics against the Stoic charge that they philosophize contrary to 'common conceptions' shared by all people. Plutarch's speaker turns the accusation back on the Stoics, arguing at length that Stoic ethics and physics are the ones that violate ordinary intuition.
Chrysippus is the essay's main target, the Stoic philosopher who, per the dialogue, came after Arcesilaus and before Carneades and 'blocked up' confusion over common notions in favor of Stoic doctrine. Plutarch quotes his works on Exhortation and Physical Questions directly to expose contradictions.
He argues it is absurd for Stoics to hold that only virtue is good yet still praise trivial acts of endurance, such as bearing the bite of a fly, as instances of that same virtue. He also attacks the idea that mutilation and disease are merely 'indifferent' while nature simultaneously justifies suicide to escape them.
He mocks the Stoic doctrine that virtues, vices, passions, and even arts are literal bodies and rational living creatures housed within the single point of the soul, and he challenges Chrysippus's claims that night, evening, and time itself are bodies.
It defends the Academy. The speaker Lamprias answers Stoic critics who called the Academics 'sophists and destroyers' of common belief by showing, point by point, that Stoic doctrine is the more paradoxical system.
Koinai ennoiai are the basic notions all humans are assumed to share simply from ordinary sense experience, such as that pain is bad or that an element must be simple. Both Stoics and Academics in this dialogue claim to uphold them while accusing the other side of violating them.
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