Guest post by James Poskett

It’s March 7th. Forgetting anything? A birthday perhaps? Charles Darwin’s has been and gone, 12th February, so it’s not him. Maybe another great of the Royal Society, Sir Isaac Newton PRS? Hard luck. A quick search of the archive reveals he was born on Christmas Day 1642. No, in fact today marks the birthday of one of my own favourite, albeit less well-known, scientists: Sir John Herschel FRS, born March 7th 1792.

Whilst doing some research for this piece I asked my friends, some budding scientists, whether they had heard of Herschel. The universal response, a dull “…who?”. This seemed odd, history is testament to the fact that Herschel was held in high esteem by his Victorian peers; he is buried in Westminster Abbey and lies next to the two aforementioned titans of science, Darwin and Newton. And Herschel was certainly not too specialist to be of relevance, having worked in (among other disciplines) astronomy, chemistry, botany and mathematics. He even coined the term “photography” having contributed to the chemical process developed by William Henry Fox Talbot FRS.


Portrait photograph of John Herschel, from the Maull studio


So, if all this wasn’t enough, I really needed an achievement which no scientist can ignore: Herschel’s work on how to do science.

In 1830 Herschel published A Preliminary Discourse on the Study of Natural Philosophy. Behind this typically grand title is a book which explains how a scientist (then natural philosopher) should go about identifying the best theories and defending them. Today we would call this the philosophy of science and, as I hope you will agree, it is something that all scientists have had to engage with, both historically and today.

Darwin himself sent Herschel a letter referring to A Preliminary Discourse stating that “scarcely anything in my life made so deep an impression on me”. Whilst Victorian letters are not short on hyperbole, historians of science have revealed that Darwin was serious about Herschel’s influence. The structure of On the Origin of Species pays close attention to Herschel’s vera causa (true cause) standards. Perhaps most prominently, Herschel believed a good theory should involve causes similar to those already known. For this reason, Darwin begins Origin by discussing the well-accepted effects of artificial selection, particularly in the decidedly tame world of pigeon fancying. Another important aspect to Herschel’s philosophy was the belief that a good theory should explain a wide range of unexpected events:

“verifications… spring up, as it were, spontaneously, into notice, from quarters where they might be least expected”

I expect this line chimes with many modern scientists. Darwin seems to have taken notice as well; the bulk of Origin is concerned with describing the vast number of phenomena that natural selection could explain: from the distribution of bird species in the Galapagos to the fossil record in Sicily.

To an extent, it is hard to avoid the philosophy of science: Darwin needed to convince his peers and the public that his potentially controversial theory was correct. As a consequence, he considered the merits of different ways to make his case (in one notebook Darwin toyed with the idea of putting his theory across in terms of Newtonian laws, something he quickly abandoned).

John Herschel, then: the philosopher of science. Will this bring him any more recognition on his birthday? As a student of philosophy I hope so! The Fellowship of the Royal Society shows a tradition which stretches well beyond the 1800s. In the twentieth century, Sir Karl Popper FRS put forward his view that scientific theories should be falsifiable (what makes science great is that it could be wrong!). And later Michael Polanyi FRS, along with Thomas Kuhn, challenged Popper’s philosophy of science, arguing that the only way to understand scientific method was to look to history and the personal experience of scientists.

So who is Herschel? I think Kuhn in particular would appreciate the sense in which he is most valuable. Not just as a philosopher of science, but as a stellar example of how history and philosophy are more than ‘nice-to-haves’, they are a part of what it is to do science. With this in mind, I hope you will join me in wishing Herschel a Happy Birthday.

James Poskett is a recent graduate of the Department of History and Philosophy of Science at the University of Cambridge. There he completed his dissertation on the philosophy of scientific method entitled “Against Method, or For Pluralism”.

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