⑥ Revolutionary Science▪On the politicization of science during the French Revolution

The French Revolution was the culmination of Enlightenment thinking. But rather than celebrating science, the revolutionaries suppressed ideas and killed the people that held them.

Jones, Steve

Revolutionary Science: Transformation and Turmoil in the Age of the Guillotine Book

2017, ISBN: 1681773090.

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Israel, Jonathan

Revolutionary Ideas: An Intellectual History of the French Revolution from The Rights of Man to Robespierre Book

2015, ISBN: 0691169713.

Links | BibTeX

In the last decade of the eighteenth century, one of the greatest experiments ever was being conducted. It wasn’t a scientific experiment, even though it was the culmination of Enlightenment thinking. It wasn’t led by scientists, although many of the most prominent leaders had discoveries and inventions to their names. And even though it was conducted in the name of progress and reason, it ended up suppressing ideas and killing the people that held them. I am talking, of course, about the French Revolution.

Hello and welcome to A History of Science: Episode 6: Revolutionary Science.


France was not a backward country before the revolution. Rather, it was closer to being the intellectual center of the world. During the eighteenth century, French academies had transformed from rigid schools teaching ancient concepts to breeding grounds for theorizing and experimentation. French public debate was alive with new ideas on natural philosophy and humanist thinking. Periodical publications, including the world’s first ever academic journal, Le Journal des Savants, disseminated these exciting new thoughts to eager French audiences.

The kings of France were amongst the enthusiastic patrons of this new scientific community. They very much liked to style themselves as enlightened monarchs of a modern state. As such, many institutions, observatories, and laboratories enjoyed the royal prefix – most notably the prestigious Royal Academy of Sciences, and were financially sponsored by the state. But individual researchers, too, were known to benefit from royal patronage. One alumnus of the University of Paris, who had become a renowned experimenter in his own right, was Pierre Polinière. He was known for exciting his audiences with demonstrations of scientific principles. At the height of his fame, king Louis XV invited him to lecture at his court. He allegedly dazzled the noble crowd by making an apple explode with an air-pump. Even Louis XVI, the ill-fated last king of France before the revolution, was known to have a keen interest in technology. Under his watch, scientists experimented with balloon flight in the gardens of Versailles, while he himself tried his hand at lock-making in his state-of-the-art workshop.

But it was in this enlightened society, inspired by thinkers such as Voltaire, Rousseau, and Montesquieu, where, in 1789, the revolutionary flash hit the pan. Frustrated by famine, taxes, and oppressive government, the lower house overthrew the political order and thoroughly reformed the state. In quick succession, parliament abolished feudal obligations, noble titles, tax exemptions, and corporal punishment. They introduced a constitution promising equality before the law, freedom of speech, and democratic representation. At the stroke of a pen, France had entered the age of modernity.

Or so the story goes. The ancient regime, the old order, was denounced as a tyrannical dictatorship, based on the arbitrary whims of a decadent aristocracy. The new France was to be built on the pillars of liberty, equality, and brotherhood – ideas that had somehow sprouted in that tyrannical intellectual climate of the ancient regime. Above all, though, the revolutionaries appealed to reason as the foundation of their ideal state. They envisioned a nation of enlightened people – citizens, not subjects – who formed a virtuous meritocracy, where no man would bow to another.

That hopeful assembly of equals in 1789 would soon be displaced by a wartime dictatorship that wielded terror as a revolutionary principle. Universities would be closed, scientists would be guillotined – all in the name of reason. In this episode, we’ll explore this ironic paradox. And we’ll start with the daily struggles of a peasant, just moments before the ominous summer of 1789.

Measures in the Ancient Regime

Imagine a peasant in pre-revolutionary France. Let’s call him Jacques. Jacques works his landlord’s fields. After the grain harvest, he goes by his landlord’s estate to pay his feudal dues. The landlord owns the scale and the weights; he determines how the shares are split. With the grain he doesn’t keep to feed his family, Jacques tries to make a profit on the weekly market in a neighbouring town. Along the way there he pays toll tax to a local customs officer – another share of his grain gone, once again determined by someone else’s weights and measures. On the market square, Jacques has to abide by the town’s local units of measurement when making his sales. Poor Jacques; he has to depend on a lot of different measures; and he has to put a lot of faith in the authorities controlling them.

This example of Jacques was not uncommon in early modern France. Measures were not standardized, and as many as seven or eight hundred different ones were in use throughout the country. You could measure weight in onces, livres, or talents, and volumes in litrons – for dry goods – or pintes – for liquids. Or you could resort to units of measurement based on labour, rather than output. A journal, for example, referred to one peasant’s day worth of work on the field, rather than the produce he yielded. Distances were commonly expressed in lieues, or leagues; there were multiple variants of leagues, however. The oldest one, the lieu ancienne, measured a little over three kilometers, while the Parisian league measured just under four. The postal league beat them both with a metric equivalent of well over four kilometers.

Many people realized this was far from ideal. Various French kings, starting all the way back with Charlemagne, had tried to introduce a nation-wide measure. This had culminated in the toise becoming a more or less reliable royal standard. Charlemagne himself had defined it as the length between a man’s outstretched arms, possibly his own. An iron bar representing this measure was kept safe in the castle of Chatelet. Not safe enough, though, since at one point it fell off and had to be hammered back in place by builders. Unfortunately, they deformed it with their blows, causing Charlemagne’s arms, and France’s official royal measure, to lose a couple of millimeters.

The Metric System

The revolutionary French government was determined to settle this age-old problem once and for all. It was, after all, a perfect example of enlightened democrats achieving what no French king ever could. They envisioned a nation-wide system of measures that would not be based on the length of some arbitrary monarch’s limbs, but on an eternal natural constant: the size of the earth.

A committee of some of the greatest minds of the age was assembled to define this new system of measurement. It included illustrious names such as the mathematician Nicolas de Condorcet and the brilliant chemist Antoine Lavoisier. They determined that the new measure should be exactly one ten-millionth part of the length of the meridian from the North Pole to the equator, in a line that passed right through Paris. Agreeing on a definition wasn’t the greatest challenge, though. Measuring the meridian’s length was.

Measuring such enormous distances was no small feat. It required delicate equipment to be set up on tall structures throughout the country, such as mountains or towers. The scientists’ plan was to measure the distance between Dunkirk in the north and Barcelona in the south, and then extrapolate those measures to find the earth’s meridian. This turned out to be a massive undertaking that would take twenty years to complete. The surveyors traveled through a country without proper roads, in bouncing carriages in which their expensive equipment was easily damaged. Circumstances during the tumultuous revolutionary years didn’t help either. To their despair, tall structures such as fortresses or churches had often been razed to the ground by the shelling of invading armies or the zeal of anti-Christian republicans. One surveyor recounted that, when he inquired about the location of a village’s church tower, the inhabitants told him that they had “demolished those steeples that arrogantly elevated themselves above the humble dwellings of the French people”.

In spite of these hardships, however, the surveyors did ultimately succeed. At the dawn of the new century they presented their preliminary findings to an international conference of scientists. Perhaps the only blemish on that significant moment was that their newly proposed meter just happened to be exactly the same size as Charlemagne’s outstretched arms.

Use of the metric system would become widespread in the decades that followed. Napoleon would spread the meter throughout Europe with every country he conquered. Later, those countries would, in turn, introduce it to their colonies all over the world. In its early years, the French republic had achieved a major scientific success. The revolutionaries had applied reason to decidedly solve a problem that had deluded the world for centuries. They were convinced it would be the first of many. And in the darker days of the French Revolution, science would be put to use for ever more eccentric and sinister goals.

The Revolutionary Calendar

Ancient local measurements of weight, volume, and distance had been successfully transformed into mathematically sound units. Time would be next. No longer would twenty-four hours of sixty arbitrary minutes constitute a day. Nor would years be counted from the approximate birth of a messiah worshipped by a superstitious, decadent clergy.

For a people reborn into reason, a day would have ten hours. An hour would have a hundred minutes. A minute would have a hundred seconds. There would be ten days in a week, three weeks in a month, and twelve months in a year. Years would be counted from the birth of the republic, 1792 – or, as the revolutionaries said, year I of the French Republic.

To give this new calendar some poetic decoration, playwright Fabre d’Eglantine was recruited to propose the names of the new months. He came up with names based on seasonal characteristics; for example, Thermidor – from Greek thermon, meaning heat – would overlap with July, the warmest period in summer; Floreal – from French fleur, or flower – would be roughly the equivalent of May, the springtime when flowers blossomed. In Great Britain, commentators at the time ridiculed the new months of the overzealous French republicans with ironic English ‘translations’ such as Wheezy, Sneezy, and Freezy for the winter months, and Hoppy, Poppy, and Croppy for summer.

The British were not entirely unjustified in their reaction, though. The decimal calendar was decidedly more difficult to use than the Gregorian one, and it wasn’t popular with anyone. French peasants hated it, because it prolonged their working week with three days. Administrators hated it, because it was notoriously difficult to apply correctly; many aspects, such as leap years, had been inadequately thought out and had to be fixed as time went by. The clergy, many of whom had been ardent supporters of the early revolution, hated it, because it set aside their sacred calendar, and reduced them to second-rate revolutionaries.

Systems of Measurement Politicized

On the outset, the metric system and the republican calendar may seem to have a lot in common; they both strive to create mathematically sound systems of reasoning for everyday use. The differences between them, however, perfectly illustrate the changing role of reason throughout the early revolutionary years. In 1789, the rationalization of the old, inefficient state with its hodgepodge of laws and taxes was a leading principle of the revolution. A few years later, though, science was reduced to merely serving the megalomaniac visions of a new elite.

Work on the metric system started early in 1790, in a spirit of liberty, equality, and progressive change. It was an ambitious initiative that demonstrated clearly how science could create fair, practical systems of thought. It would ensure that no feudal overlord would ever again demand a greater share of the harvest, simply because he happened to own the scale. The decimal calendar, on the other hand, was realized in 1793, by a paranoid wartime government that saw counter-revolutionaries everywhere. It was purposefully created as a political instrument to increase control over the French people. Longer working weeks would make peasants more productive. The abolition of sundays would make them less religious. Whoever controlled the calendar, controlled religion, economy, and ultimately, the nation itself.

Seen from a political perspective, both systems of measurement are polar opposites of each other. The metric system was designed to serve the people; the decimal calendar was created to make the people subservient to the state.

In the remainder of this episode, we’ll take a closer look at how the role of reason changed over the revolutionary years. We’ll do so through the eyes of one of the most detested characters in the French Revolution, who surprisingly, started out as a scientist himself: Jean-Paul Marat.

Jean-Paul Marat’s Scientific Achievements

Jean-Paul Marat was not French by birth. He was born in Switzerland, to a family of religious refugees. His father, despite being well-educated, had a hard time providing for his family. Marat must have realized at a young age that as a Huguenot, he was a marked man. Any success he sought he would have to gain through tireless perspiration.

Marat left for Paris when he was still in his teens. There he studied medicine, receiving his medical degree for a treatise on curing gonorrhea, with which a friend of his was reportedly afflicted. To increase his social standing, he entered into the world of Parisian intellectuals. He started publishing on the philosophical issues of the day: liberty, equality, slavery. His sharp pen did get him noticed, and before long he found himself in the employ of the comte d’Artois, the younger brother of king Louis XVI.

Using his new-found wealth as a court physician, Marat concentrated his efforts on other fields of science: fire, electricity, and light. He performed countless experiments, wrote down their results in voluminous tomes, and, to his amazement, found that not all perspiration pays off.

When Marat completed his first scientific book, in which he argued that fire was a fluid rather than a material element, he sent it to the Royal Academy of Sciences for appraisal. The academy reviewed his work and was impressed with the 166 “new, precise, and well-executed experiments” Marat described in it. They did not, however, endorse his conclusions. That did not stop Marat from publishing his book with their ringing endorsement prominently covered. Infuriated members of the academy, among them renowned chemist Antoine Lavoisier, demanded he rectified. Yielding to the pressure, Marat removed the endorsement from his book. It would be the start of his tenuous relationship with the scientific establishment.

When he started conducting a second set of experiments, this time on light, Marat involved the academy early on. Over a period of seven months, he performed all experiments in front of a delegation of scientists. His peers were again impressed by his experimental zeal and persistence, but felt that they did not justify the conclusions he drew. Once again, Marat did not gain the endorsement of the academy that he so desperately sought. Disillusioned, he published his book in England rather than France. When completing his third and final academic book, on electricity, he didn’t even bother to involve the academy at all.

When the revolution broke out in 1789, Marat discarded science altogether to devote himself entirely to politics. He would not, however, forget the scientific community, or how he felt they had mistreated him.

Marat and the Revolution

A few years later, things had changed dramatically for Marat, and for France. Marat had started publishing a popular daily newspaper, l’Ami du Peuple – the Friend of the People – in which he expressed his increasingly radical political views. His popularity as a journalist got him elected to the new parliament. Radical politicians, Marat included, tried to appeal to popular opinion with ever more extreme proposals, culminating in them voting to execute the deposed king Louis XVI. As France was being invaded by foreign powers, determined to restore order and absolutism to the country, the French people entered into a state of constant fear of invasion and paranoia. Marat fueled the fire by constantly publishing accusations of suspected counter-revolutionaries, especially within the old noble ranks. This culminated in the notorious prison massacres, in which over a thousand prisoners were lynched by mobs of fired-up citizens.

Gone were the days of equality and brotherhood. The will of the people, carefully molded by Marat’s journal and catered to by extremist politicians, ruled. Anyone not considered a member of the common French people was suspect. This hatred of the aristocracy did not end with the old nobility. The aristocracy of intelligence was denounced just as well.

Marat allied himself with Maximilian Robespierre, the orchestrator of the revolution’s most extreme and violent period. Together, they declared war on what they saw as the scientific aristocracy. “No race of men is more dangerous to liberty, more an enemy to equality,” Robespierre declared, “than the aristocrats of science.” Science should directly serve and benefit the people, or it should not be conducted at all. “What do the diverse hypotheses with which certain scientists explain natural phenomena matter to legislators?”, he continued. Common sense should rule instead. In 1793, by order of Robespierre’s government, all universities, all academies, and all literary societies were closed down.

The Paradox

So here we are. In 1793, the darkest days of the French Revolution. Universities have been closed. Scientists, many of whom having been born into noble families, are being executed under the guillotine. And in a perverse irony, the people are encouraged to literally worship reason. A Cult of Reason has been invented to substitute Christianity. It encourages worship of concepts such as truth and liberty, usually portrayed by young women in Roman attire, complete with white togas and laurel wreaths. In a Festival of Reason, churches are converted into Temples of Reason, its altars replaced with ones dedicated to philosophy. The irony cannot be greater: places of worship being converted into farcical temples of reason, while science’s real temples, its universities and academies, stand empty.

Was the French Revolution, at this point, still devoted to scientific principles? I think not. Never mind the revolutionaries’ constant use of words like reason, rationality, and truth, the scientific culture had become oppressive, dogmatic, and anti-intellectual. There was no longer a free public discourse, a sharing of ideas, or a culture of investigation. The revolutionaries’ use of scientific words, by 1793, had become just decorum.

Now, there’s no denying that the French Revolution was strongly based on philosophical ideas. It also developed forms of state civics and nation building that greatly influenced modern states, and which are still relevant today. In the short term, however, France’s scientific community suffered. Science became a political instrument, rather than an independent entity. Scientists were expected to cater to the expectations of the populace, rather than follow their own academic interests. The intellectual culture that had formed Rousseau, Voltaire, and Montesquieu, whose ideas had made the revolution possible in the first place, was suppressed and replaced with dogma. It would take a decade before the universities were again officially recognized by Napoleon, and many more before France regained a scientific culture to form the likes of Louis Pasteur and Marie Curie.


How did it all play out for the characters in our story? Jean-Paul Marat was murdered by a woman whose whole family had been guillotined. For a short time afterwards, busts of his head were used to try and instill a sense of martyrdom into the followers of the Cult of Reason. In 1794, however, all prominent members of the Cult were guillotined in one of Robespierre’s power plays, practically ending its existence. A few months later, Robespierre himself was guillotined, finally ending the revolution’s darkest days. It had cost the lives or careers of dozens of renowned scientists. Among those who died were all scientists I mentioned in this episode. Gilbert Romme, mathematician and creator of the Republican Calendar, committed suicide after having been sentenced to death. Nicolas de Condorcet, mathematician and instigator of the metric system, was found murdered in his cell. Antoine Lavoisier, chemist and co-creator of the metric system, was guillotined because of his noble background. When appealing for his life, the judge perfectly demonstrated the arrogance and hypocrisy of the time: “The Republic has no need for scientists”.

If you enjoyed this episode, and want to know more about the strange paradox of science during the French Revolution, I recommend two books that served as the main sources for this episode. The first is an easy read, Steve Jones’ No Need for Geniuses, ideal for an accessible overview. If you want to get all in, try Jonathan Israel’s Revolutionary Ideas, a dense academic work detailing the philosophy that shaped the revolution. Oh, and if you’re at all interested in the French Revolution, do yourself a favor and listen to Mike Duncan’s Revolutions podcast.

Thanks for listening. Hopefully until another History of Science.