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"Otherworldly Science: Margaret Cavendish’s Critique of the Experimental Method" by Peter West

White house on hill

From The Philosopher, vol. 109, no. 1 ("Nothing").

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One of the most remarkable texts in the history of science is Robert Hooke’s Micrographia. Published in 1665, Micrographia was the first book to provide an in-depth and varied account of what everyday objects look like through the lens of a microscope. Using both detailed written descriptions and large fold-out illustrations (most likely composed with the assistance of his friend, the architect Christopher Wren), Hooke wanted to show – and this really is the operative word – the seventeenth-century reading public what the world looks like under a microscope.

The text itself is a marvel. Even today, it is a joy to peruse the vivid drawings of various plants, animals, and household objects, and put yourself in the shoes of Hooke’s contemporaries as they did the same. One can only imagine what it must have been like to unfold an enormous pop-out illustration of a woodlouse and learn, for the very first time, that they are considerably more monstrous than they appear via the naked eye. The idea of magnified insects is a familiar one today and has captured the imaginations of writers and filmmakers in recent popular culture – but Hooke’s readers weren’t reading sci-fi, they were being informed that such creatures actually inhabited the world around them.

As an early attempt at what we would now call “public philosophy”, the intellectual and cultural impact of Hooke’s Micrographia cannot be understated.

One early reader and enthusiast was the famous diarist Samuel Pepys who (in January 1665) ordered a copy of the text from his bookseller because it was “so pretty”. Once his copy arrived, Pepys stayed up until two o’clock in the morning reading it and then declared it “the most ingenious book that ever I read in my life”. But Hooke did not just have aesthetic or even purely scholarly aims in mind. As various historians have argued, Micrographia was neither intended to be solely a contribution to ongoing scholarly debates nor something pretty to keep on one’s bookshelf. Rather, it was an attempt to get the wider reading public to completely re-think the way they understand the world around them. In John T. Harwood’s words, Hooke wanted his audience to “take another look” at the world (for more on philosophical responses to microscope in this period, see Catherine Wilson’s The Invisible World: Early Modern Philosophy and the Invention of the Microscope). As an early attempt at what we would now call “public philosophy”, the intellectual and cultural impact of Hooke’s Micrographia cannot be understated.


Hooke’s work was not, however, universally acclaimed. In 1666, a year after its publication, another text appeared in London, entitled Observations upon Experimental Philosophy. To which is added, The Description of a New Blazing World. This treatise included a prolonged critique of the experimental method in science championed by Hooke and his associates in the Royal Society of London. The Observations was the latest piece of writing from another remarkable seventeenth-century figure: the natural philosopher Margaret Cavendish, the Duchess of Newcastle (who was also a poet and playwright). Even by the standards of the time, Cavendish was a prolific writer and her philosophical works include pertinent critiques of prominent thinkers like Descartes, Hobbes, and many others.

In May 1667, Cavendish visited London, having been invited to attend a meeting of the Royal Society. Once again, Samuel Pepys was on hand to describe her visit and explains that it was near impossible to even catch a glimpse of her. He blames this on a throng of coaches and valets constantly surrounding her and, to the contemporary eye, his descriptions of Cavendish’s trip invoke images of the Beatles being chased around the streets of London.

In many ways Cavendish was a radical thinker. For example, her natural philosophy involved a rejection of two of the most dominant metaphysical worldviews at the time: atomistic philosophy, which has its roots in the Ancient Greek thinker Democritus, and mechanistic accounts of the natural world, which were accepted by many of the most prominent scientists and philosophers in seventeenth-century Britain (including Robert Boyle and, later, John Locke). Yet, when it comes to scientific instruments and the revelations contained in Hooke’s Micrographia, Cavendish’s response seems peculiarly conservative.

In the Observations, she develops a two-pronged case against Hooke’s endorsement of microscopes and telescopes. First, she argues that since we cannot verify with the naked eye that insects, for example, really look like they do in Hooke’s illustrations, we cannot be certain that observations made using a microscope are accurate (for instance, she doubts the plausibility of the observation that flies have up to 14,000 eyes). Second, she argues that what science should really focus on is helping us to better understand the world we see with the naked eye. What good is it, she asks, to learn that under certain circumstances (i.e., through the lens of a microscope) household objects, plants, and animals look radically different? Hooke’s observations included the fact that a needle looks blunt under a microscope and that a block of wood is much more porous than it appears to the naked eye. That’s all very well and good but, Cavendish asks, what can that tell us about the world that we actually inhabit; one full of tiny insects, sharp needles, and solid blocks of wood?


One might be tempted to dismiss Cavendish’s objections as short-sighted (no pun intended). After all, we can now point to developments in, say, cancer research as just one of myriad cases where knowledge gained by looking at the world through the lens of a microscope has been crucial. But it is important to note that the kinds of question outlined above are just that: questions. The developments in science advertised in Hooke’s Micrographia were in their earliest stages and his findings were shocking. Cavendish is responding to the considerable fanfare generated by the likes of Hooke, his colleagues in the Royal Society, and wider readers such as Pepys. She wants to cut through this furore and straight to the point: what can these scientific instruments actually tell us about the world?

There is one passage in Hooke’s Preface to Micrographia which Cavendish seems to have found especially problematic. In this passage, he explains that microscopes and telescopes not only help us to study the “already visible world” but can also discover “new Worlds and Terra-Incognita’s”. Borrowing terminology that would have been found on a map at the time, Hooke’s claim is that there are many unknown worlds out there waiting to be discovered by scientists armed with microscopes and telescopes. Even though Hooke was most likely speaking metaphorically, Cavendish’s response suggests she thought it revealed a more pressing issue with his scientific project.

Cavendish never questions Hooke’s claim that these instruments can show us new worlds, but instead raises the question of why that makes experimental philosophy a task worth pursuing. In the Observations (in the “Dedication” to the Duke of Newcastle), she writes:

The Truth is, My Lord, that most men in these latter times, busy themselves more with other worlds, than with this they live in, which to me seems strange, unless they could find some art that would carry them in[to] those celestial worlds[.]

Her concern is this: accruing information about a “world” will be of benefit to us if we already inhabit or could possibly inhabit it. But we neither currently inhabit the “microscopical worlds” and “telescopical worlds” that scientific instruments show us, nor will it ever be possible for us to do so. The illnesses that inflict us, our feelings of hunger or pain, social needs such as housing, trade, travel, and infrastructure, political issues concerning the church and justice system, and matters of war and peace, all take place in the macroscopic world of everyday experience. What, then, is the good in accruing information about the microscopic world? Hooke’s Micrographia is full of amazing facts and illustrations but Cavendish wants to know what purpose it serves. Why think that information about “new worlds” can inform us about our own?

Cavendish clearly did not think that proponents of the emerging professions of microscopy and telescopy had done enough to provide a satisfactory answer to such questions, and writes:

And therefore, I confess, I have but little faith in such arts [by which she means artificial or man-made instruments], and as little in telescopical, microscopical, and the like inspections; and prefer rational and judicious observations, before deluding glasses and experiments[.]

In short, Cavendish does not think Hooke has made it clear enough why we should trust microscopes and telescopes – “deluding glasses and experiments” – to inform us reliably about the world around us. Instead, she thinks, Hooke (to his detriment) focuses on the novelty of the things they reveal.

Hooke himself, in another work (Of the True Method of Building a Solid Philosophy) agrees that “the Pictures of things which only serve for Ornament or Pleasure… [are] rather noxious [i.e., harmful] than useful”. But clearly Cavendish did not think he had done enough to show that the pictures in Micrographia were useful rather that “noxious”.


Over the course of her lifetime, alongside her works of natural philosophy and science, Cavendish wrote poetry, plays, and short stories. She was also fascinated by the writing process itself and had much to say about her own writing as well as the relationship between the different genres that it straddles. One way of learning more about why Cavendish thinks that Hooke’s claims about the discovery of new worlds under a microscope or through a telescope are so problematic is by looking at her fiction-writing, where she embarks on her own attempt not just to discover but create “new worlds”.

Cavendish’s best-known piece of fiction is the novella A Description of a New World, Called the Blazing World which was published alongside her philosophical Observations. The two works are, she tells us, “joined… as two worlds at the end of their poles”. As the historian of philosophy Emily Thomas (in her recent book The Meaning of Travel) explains, Cavendish is here playing off the fact that many seventeenth-century maps depicted the two faces of the earth alongside one another and joined together at the pole. The Blazing World charts the journey of an unnamed protagonist who is abducted and taken aboard a ship heading towards the North Pole. Once the ship reaches and passes through the North Pole, she finds herself in a new world whose sky is full of bright stars even in the middle of the day: the Blazing World. The world is inhabited by anthropomorphic animals, including bear-people, fox-people, bird-people, and worm-people, who take the protagonist to their Emperor. The Emperor is immediately stricken with adoration and marries her, making her the Empress of the Blazing World.

The beauty of The Blazing World is in the details, and there is much more that could be said about the story (for example, in a bizarre fourth-wall-breaking turn of events, the Empress is offered the chance to summon the spirit of a great thinker and chooses the author: Margaret Cavendish). However, I want to focus on what Cavendish is doing in this text: what her aims are and how she achieves them. In her dedication “To The Reader”, Cavendish explains that she wrote The Blazing World and attached it to her philosophical Observations, both “for my own sake, to divert my studious thoughts” and “to delight the reader with variety, which is always pleasing”. And yet, there seems to be something more significant going on.

That The Blazing World was written with an agenda in mind becomes clear when we consider the fact that the protagonist of the story is from the same social, political, and intellectual context as Cavendish (i.e., seventeenth-century England). The Empress has the power to set the agenda for the men who make up the scientific and philosophical academies in the Blazing World and is able to construct a society founded on her own social, political, and scientific views which (unsurprisingly) are the same views one can find espoused in Cavendish’s Observations and elsewhere in her philosophical writing. This would have been a rare position for a woman to find herself in in seventeenth-century England. However, since Cavendish has created a new world, one made out of what she calls “wit”, she is able to determine that this turn of events takes place.


The best way to understand what Cavendish is doing in The Blazing World is to think of it as a thought experiment. Like any experiment, a thought experiment involves running a scenario under specific, variable conditions in order to determine what the outcome of that scenario is when those conditions are in place. The difference with a thought experiment, however, is that it all happens within a text, in conversation, or in thought – rather than in a laboratory. By considering The Blazing World as a thought experiment, we can appreciate why Cavendish saw the value of creating other worlds in fiction.

What is important, and what differentiates Cavendish’s focus on other worlds from Hooke’s, is that Cavendish is hoping to better understand our world by creating new ones. As a citizen of seventeenth-century England, it is unlikely that Cavendish could actually observe what would happen were a woman elevated to a position of power and granted the intellectual freedom of men in similar positions. But she can run a scenario and put in place certain conditions – for example, the Empress has total control over the scholarly and political activities of the denizens of the Blazing World – and by allowing the scenario to run its course, gain a better understanding of what would happen were this scenario to take place in our world. Cavendish evidently thought that if such conditions were met then very good things would happen; not only do the Empress’ designs lead to an age of prosperity in the Blazing World but she also resolves a war taking place in her own world – and wins a legal trial on behalf of the Duke of Newcastle to-boot.

Despite Cavendish’s humble suggestion that The Blazing World was intended to “delight the reader with variety” it is not (to borrow Hooke’s words) merely a set of “Pictures… which only serve for Ornament or Pleasure”. While Hooke, his colleagues in the Royal Society, and enthusiastic readers of Micrographia fawned over the shocking revelations presented via his drawings and descriptions of “new worlds”, Cavendish denied that there were any obvious upshots for our understanding of the world we actually live in. That doesn’t mean that she thought the burgeoning professions of microscopy and telescopy should be halted immediately but rather that their proponents needed to do more to show that these arts are reliable (and valuable) sources of information.

The study of “other worlds” can only be worthwhile if it ultimately helps us to better navigate the world which we currently inhabit.

In other words, Cavendish wanted evidence that Hooke’s instruments had the power to do more than just reveal “Terra-Incognita’s” that merely amuse and distract. That’s because, she thinks, the study of “other worlds” – like her Blazing World – can only be worthwhile if it ultimately helps us to better navigate the world which we currently inhabit. To be fair to Hooke, he is keen to indicate that the observations made using microscopes and telescopes can provide us with new insights into the world around us. For example, he suggests that microscopes may reveal to us that things in nature “are manag’d by Wheels, and Engines, and Springs” and thus understandable in the same way we understand things “devised by humane wit”. This would provide us with “Mechanick Knowledge” of nature and allow us to predict cause and effect relations much more accurately than the naked eye allows us to. Yet, for the most part, Hooke’s suggestions remain fairly non-specific; he seems more interested in emphasising the advantages the experimental method in science has over scholastic “armchair” metaphysics. Cavendish pushes him to stop looking over his shoulder at medieval philosophy and to outline some clear upshots of the experimental method.


As I see it, the take-away point from Cavendish’s critique of Micrographia is that while scientific progress may well emerge out of the discovery of “new worlds” it is not constituted by it and the two should not be conflated. Thus, it seems plausible to attribute to Cavendish the view that scientists should be following a general rule of thumb: if you cannot be sure that your findings reliably inform us about the world we inhabit then think carefully about whether what you are doing really constitutes scientific progress. Cavendish’s writing thus offers a challenge to the experimental method which came to prominence in the academies and laboratories of seventeenth-century Britain. Members of the Royal Society, including Hooke, insisted that we ought to be doing our utmost to go out into the world and collect data. Put very simply, Cavendish’s response is an attempt to elicit greater clarity when it comes to the question: why?


From The Philosopher, vol. 109, no. 1 ("Nothing").

If you enjoyed reading this, please consider becoming a patron or making a small donation.

We are unfunded and your support is greatly appreciated.

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