Do snails have eyes? Seventeenth century ‘mythbuster’ and science communicator, Sir Thomas Browne, investigates
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Version 0 of 1. Sir Thomas Browne was born in 1605, in London, and although his mother and step-father ‘wasted & consumed’ much of the estate he and his four siblings should have inherited, enough money was saved to send him to Winchester College. From there he went to Oxford University, and then studied medicine in Montpellier and Padua before graduating with an MD from Leiden. After an apprenticeship he settled into medical practice in Norwich in 1637, which was a very fashionable commercial city, the second largest in England. Pseudodoxia epidemica: the false beliefs of the elite? Browne’s European education exposed him to some of the latest thinking in medical practice, including training in anatomy and dissection – practices that were beginning to challenge and criticise the traditional authoritative works in medicine, such as those by Hippocrates and Galen. This included William Harvey’s discovery of the circulation of the blood , which Browne said was a “discovery I prefer to that of Columbus”. His leading work of popular science writing was Pseudodoxia epidemica, or Enquiries into very many received tenets and commonly presumed truths, first published in 1646, and then rewritten, edited and republished in five new versions, the last coming out in 1672. The Latin title is roughly translated as ‘vulgar errors’, but here the word ‘vulgar’ means ‘commonly held’, rather than ‘belonging to common people’. What Browne systematically studied were the facts about the natural world, about history, and about religion, which were ‘commonly’ included in authoritative encyclopaedias and classical textbooks read by the literate and wealthy. Browne does not suggest we ignore the writings of authority figures, but rather that we should combine their knowledge with two other ways of finding things out: reason and experiment. Sometimes this is deductive, that is we already know some rules or laws about how the world works, and therefore we can use logic and reasoning to apply that knowledge to new subjects. For example, by thinking about anatomy we can find an alternative explanation for the common belief that peacocks are ashamed of their feet or legs; maybe this is due to the fact that a peacock’s anatomy prevents it from looking at its legs without dropping its tail display, which people might interpret as a sign of shame. Alternatively we can use induction, where we gather information about a particular topic, and use that data to come up with a new idea or fact about the world. Browne suggests that experiments and experience are good ways to generate information: for example he investigated the suggestion that a pot can hold as much water when its full of ashes as it can when it is empty, and that a dead kingfisher hung on a string can indicate the direction of the prevailing wind. The various editions of Pseudodoxia Epidemica show that Browne wasn’t afraid to change his mind; when it came to the question of “whether Snayles have eyes” early editions discuss his dissection of the horns of snails and Browne says that “I am not satisfied that these are eyes”. By the last edition of 1672 he says he now believes, thanks to “the help of exquisite [magnifying] Glasses”, that “those black ... spots or globules [are] their eyes.” Religio Medici: the false beliefs of religion? Browne’s fame wasn’t based on his mythbusting book but on an earlier publication, Religio Medici (the faith of a doctor). Written at a time when ‘vulgar belief’ claimed that three in four doctors were atheists, Religio Medici is a personal account of faith, and a defense of Protestant values, for which reason it was placed on the Papal list of prohibited books. While Pseudodoxia uses religious metaphors to explain the processes of reason and error, as well as exploring the truth of biblical stories, Religio Medici uses science and scientific metaphors to understand and explain religious faith, including digressions into alchemy and astronomy. It is hard to imagine many contemporary science communicators writing both a hugely popular work slaying common misconceptions and promoting reason and the scientific method, and an even more popular book about the rationality and meaning of religious faith. Of course, the great majority of people we think of as scientists have also been believers, and whether we like to recognise it or not, their faith has, at least sometimes, had a positive influence on their intellectual contributions. One of the most obvious influences is the practice of exegesis – that is the close and critical reading of the Bible or other texts to try and understand their true meaning. This can be seen as an influence in the work of many writers from the sixteenth century onwards, not just in the way that they think about and organise their material (for example, with running commentaries, in the style of Biblical annotations) but also as a justification for their use of investigation, reason, and critique. Historian of science, Martin Rudwick, has argued that Biblical exegesis, especially the construction of chronologies, was crucial in shaping the science that became geology, including the discovery of the earth’s enormous age. (His book Earth’s Deep History: how it was discovered and why it matters recently won the British Society for the History of Science’s Dingle Prize for a popular history book; I was one of the judging panel and can thoroughly recommend it). Why do we get things wrong? Browne spends several chapters of Pseudodoxia explaining why people are so fallible. Satan, of course, plays a role in misleading us, but there are less supernatural forces at work too. He suggests we are naturally credulous and supine, i.e. we tend to believe what we hear and don’t investigate for ourselves, and that we tend to be too trusting of sources we think of as authoritative (how often do we share a news story or picture without checking if it’s true first?). We can also be misled by our senses: this can be a simple mistake, for example, based on what we can see, the earth seems bigger than the sun and the moon bigger than the stars. But senses can also be bad for induction and reason – our own experience of the world is often very small and limited, so making assumptions based on just our own opinions and knowledge may lead us astray. And, of course, there are people out there trying to fool us – Browne specifically mentions soothsayers, quacks, and politicians. The latter, he says, use the ‘good of the nation’ or the ‘security of the state’ to mislead us about their true intentions: Satistes and Politicians, unto whom Ragione di Stato [‘reason of state’] is the first considerable, as though it were their business to deceive the people, as a Maxime do hold, that truth is to be concealed from them, unto whom although they reveale the visible designe, yet doe they commonly conceale the capitall intention. Pseudodoxia has a whole section dedicated to investigating and debunking pictures; Browne would have had a field day with the uncredited and doctored images circulated on Twitter. Vanessa tries to avoid retweeting these @hps_vanessa |