Deities were, in ancient Greek and other cultures alike, a prominent part of the world. Although invisible, the divine was made apparent by the natural world’s phenomena, the authority of poets, or dreams and visions.
At the dawn of Western philosophy, this level of belief started to erode. The first seeds of the history of doubt were planted by Pre-Socratic philosophers, who introduced a new way of inquiring into the world and the place of human beings in it.
Socrates challenged all previous conceptions of life, and because he questioned every faith, his contemporaries called his thought “atheism” — for which he was later indicted. Socrates’ use of doubt to challenge the world’s knowledge didn’t make him a skeptic, though: while he considered himself ignorant, he was aware of that. Doubt and truth were reconciled.
His disciple Plato further leveraged doubt to question how real is the understanding of our world; with his allegory of the cave, he argued that just as things are more real than their shadows, then there was another realm beyond the visible that was more real than the things themselves.
Plato’s greatest student, Aristotle, founded his own school and gave doubt a whole new path. Aristotle’s empirical conception of the universe is essential in the history of doubt because it championed rationalism. Throughout his work, he called for proofs and demonstration and worked out the beginnings of whole disciplines. Arguably, Aristotle was the first real scientist and the inventor of science as we know it. His primary objects of study were the observable things around him.
The most prominent cases of doubt date back to the Hellenistic period, a time in Mediterranean history between Alexander the Great’s death in 323 BC and the rise of the Roman Empire, as signified by the conquest of Ptolemaic Egypt in 32 BC. This period was so permeated by doubt that its philosophers were the original Cynics and Skeptics.
The Hellenistic period which marked one of the significant changes between two very specific historical eras. In a way, the history of doubt is written in the in-between times—those defined by the lack of something we can’t rely on anymore. Plato and Aristotle lived in a time when the individual poleis, the ancient Greek city-states, began to break down. Alexander the Great’s death coincided with the loss of control on the new cosmopolitan network of urban centers he created under his reign, which spanned from the Adriatic Sea to the Baer river in India.
“Doubters in every century have made use of that which came before,” explains philosopher and historian Jennifer Hecht in her book Doubt: A History. “Patterns of questioning have mirrored certain types of social change, and it’s through these patterns that we can compile a history of doubt,” writes Hecht.
As a philosophical school or movement, skepticism arose both in ancient Greece and India.
In India, the Ajñana school became known as the radical Indian skepticism as it didn’t believe in karma but in the fact that suffering is inevitable. In Greece, philosopher Gorgias argued that nothing exists, that even if there were something we could not know it, and that even if we could know it, we could not communicate it. Cratylus pushed it even further: he refused to discuss anything and would merely wriggle his finger, claiming that communication is impossible since meanings are constantly changing.
In the East, the history of doubt isn’t related to the divine as much as it is in the West. And yet, doubting the karma “was marvelously similar to doubting God in the West,” writes Jennifer Hecht.
In the recollection of doubt in Chinese history up until the first century CE, the historian and philosopher traces a fascinating line connecting Taoism, Confucianism, and Buddhism: they all assert “that our deepest assumptions about life are misleading in the extreme.” And these erroneous assumptions are the cause of our suffering. The act of doubting, for the adherents of these beliefs and religions, becomes necessary to reach freedom.
In India, the earliest example of radical doubt dates back to the seventh century BC. The Charvaka philosophy rejected inference as a means to establish valid, universal knowledge and metaphysical truths. Fast forward to about 200 CE, Brahman priest Nagarjuna wanted to know how the Buddha’s system really worked. Drawing on the sutras, he argued that everything our human minds come up with as a duality is equally wrong. We define the night as the opposite of the day, for example. Knowing that ordinary knowledge is useless for seeing the truth is the condition that allows the rising of prajna, the transcendent, intuitive knowledge.
A history of doubt would not be complete without mentioning the ancient Romans. Cicero, Lucretius, Pliny the Elder, Emperor Marcus Aurelius, Sextus Empiricus, and Lucian of Samosata were among the great thinkers who “invented some stylish new doubt and brought many older traditions of doubt to a culmination,” reflects Hecht. They schooled themselves in the history of Greek thought and then explained it to their peers in Latin. In doing so, they offered the most shapely theories of doubt.
With Christianity and after the Roman empire crumbled, the direction of doubt was, in a way, reversed: doubt was about the individual’s ability to believe. Religion was set up around the idea that belief is hard and that we must work towards it. Managing one’s doubt became the central drama because Jesus challenged people to have faith.
Augustine of Hippo, who died in 430 CE, about 40 years before the end of the Roman empire, praised doubt as the road to knowing anything, as long as it does not question God. But the exile of doubt from the West was completed a century later, when the Christian emperor Justinian outlawed paganism and closed the Epicurean Garden, the Skeptic Academy, the Lyceum, and the Stoic Porch. For eight centuries, the philosophies representing the beacons of doubt and rationalism were banished from Europe.
Renaissance and Reformation mark the comeback of doubt across Europe. The rediscovery of Cicero’s letters by Italian scholar Petrarch, who died in 1374, and the correspondence with writer Giovanni Boccaccio, author of the Decameron, officially kick-started the Renaissance. The following century was another profound change: the invention of the printing press allowed not just the distribution of the Bible but also of Lucretius’ On the Nature of Things. The idea that people need threats of heaven and hell in order to be moral was rejected, and demons and angels were not real anymore.
But the great unbeliever was Niccolò Machiavelli. He shook the general political idea that a leader should be a moral guide for people to follow to go to heaven. Erasmus’s call for reform was the result of deep skepticism. The tension spread like fire around Europe. While the Inquisition tried to impose control over the huge waves of doubt that were shaking society, the wind of change was blowing much harder.
To determine truth, theorized mathematician René Descartes, we must find out if there is one thing that we can know for certain and build from there, just as in ancient geometry. Everything, for Descartes, was an illusion. The tool to deconstruct it was doubt. So there we have it: cogito, ergo sum. I think, therefore I am.
Copernicus and Galilei redefined the notions and knowledge of astronomy. Travels and explorations increased the reasons for doubt, and bars or public houses became the place to find radical talk—often accompanied by coffee and tea, not just alcohol. Doubters of the eighteenth and nineteenth centuries such as Henri de Saint-Simon, Charles Fourier, and Pierre-Joseph Proudhon pushed the boundaries to establish the terms of democracy.
Science expedited the nineteenth-century belief that doubt had turned a corner. The twentieth century, which shares so much with other peak cosmopolitan moments of human history, unveiled the deep skepticism we have about our ability to understand the world, say anything true, or find a universal value.
Freud’s discussion of doubt in his work, the deep shockings after the first and second world wars, the threat of the Cold War and decolonization, made clear that to approach truth, we need to look at things from many vantage points. “Nowadays, all the classic forms of doubt run wild,” concludes Jennifer Hecht. We are living in a culture held together by a shared dedication to inquiry—a perfect time for doubt-lovers.