Pluto IS a Planet

STOP PRESS

Posted by Thomas Scarborough

There has been no small commotion surrounding the reclassification – or demotion – of the former planet Pluto.  First to dwarf planet status, then to minor planet, and finally to plutoid. This post explores some of the philosophical aspects of the issue.

Following the discovery in the 1990's, that various bodies orbit the sun in the area of Pluto, Pluto was taken off the 'planets' list. The International Astronomical Union, in 2006, ruled that a planet had to be an object which met three basic criteria: 1. it orbited the sun, 2. it was rounded by its own gravity, and 3. it 'cleared the neighbourhood'. Pluto failed on the last criterion. It was one of a crowd, in the Kuiper belt.

The reaction to Pluto's demotion was 'hectic'. The California State Assembly declared it a 'scientific heresy', while the Illinois Senate ruled it 'unfair'. And when the Hayden Planetarium, in 2000, famously unveiled a new model of the solar system with only eight planets, the ensuing controversy was still making headlines a year later. In 2007, the American Dialect Society chose 'plutoed' as its 2006 Word of the Year – meaning 'to demote or devalue someone or something, as happened to the former planet Pluto.' 

In terms of the philosophy of language, the reaction covered the whole gamut of linguistic interpretations. Most basically, there were those who fell in the 'prescriptive' camp – prescribing definitions: 'It's official,' or seeking to prescribe them: 'We've signed a petition to reverse it.'  On the other hand, there were those who fell in the 'descriptive' camp – describing words as we already use them: 'I've always called it a planet,' 'It looks like a planet,' 'It's only what some people say,' or 'Ask your heart.' Channel 4 News summed up this dichotomy simply: Some call it Planet X, some call it the ex planet.

This week, for the first time, the New Horizons probe saw the features of Pluto close up. As the … call it, 'object' came closer into view, Alan Stern, lead researcher of the New Horizons mission, gave a nine-fingered salute (a semiotic code, we call it) to indicate that the solar system has nine planets – not eight. @NASA tweeted, 'How about we call Pluto a planet again?' while the New York Post simply described our tour of 'all nine planets'. The 'Twitterverse' erupted in one great chorus: 'It's a planet!' while the prime mover behind the reclassification of Pluto (forbid that we should name him) was no longer said to drive a car, but a 'getaway car'.

Part of the trouble is that, the closer we look at the 'plutoid' definition, the faster it seems to flee away. The definition is dependent on other definitions – above all what it might mean that an object has 'cleared the neighbourhood'.  Francis Bacon recognised this difficulty four-hundred years ago. The definitions of things consist of words, and words beget words. For instance, if a planet has cleared the neighbourhood, then what is the neighbourhood? And if Pluto were moved to another neighbourhood, elsewhere in the solar system, would it still be a mere plutoid? The answer is by no means clear. Not to speak of the public suspicion that our definitions are too much what we choose to make them anyway.

The furore, at root, highlights the tension between prescriptive and descriptive definitions in our language. This became a major linguistic problem, for the first time, in recent generations.  'Prescriptive' is something which is prescribed. French and Afrikaans are examples of prescriptive languages (there are language boards which define them), while English is not. English is 'descriptive', in that it gains words and sheds words, the meanings of words morph all the time, and we simply describe what has happened to them. Our English language is no longer the Queen's English (prescriptive) but it is what it is (descriptive).

What is the real difference between 'prescriptive' and 'descriptive'? Prescriptivists will typically say that words have definite features, or components – the  International Astronomical Union's definition being an example:  a prescriptive definition of a planet says that it has three major features – basta. The descriptive definition is less well defined. Words are what they mean. But what do they mean? Does one know their meanings, too, by their features? Say, a planet is an object which orbits the sun, and is rounded by its own gravity, but it has cleared the neighbourhood.

Someone in the 'Twitterverse' suggested another possibility: words mean what we feel – and we feel that Pluto is a planet. But how might this look, more exactly? Take the example: 'Pluto is a planet. The mountains show it. Geological activity, too. And the atmosphere.' These sentences go hand in glove. We understand them instantly. Yet notice that, after the first full stop, we have made no explicit reference to Pluto.  No dictionary definition will show us that a planet has mountains – or geological activity or an atmosphere. These are what we call bridging inferences.  The strange thing is, therefore, that without referring to the planet, we all know that we are talking about the planet.

The fact that we know (or feel) that mountains, for instance, belong to a planet is all the more strikingly seen when we use a bridging inference which does not work: 'Pluto is a planet. The gearbox shows it.' This does not fit, simply because we do not ever infer that it does. All the time, in fact, we know what we are talking about only through inference. 'Keep the chicken livers off the table. The cat is in there' – yet one will find few clues about chicken livers in our dictionaries, and none which suggest that cats have anything to do with tables. Or, 'He had an apartment in the Bronx. The karma was bad.' The same applies.

Notice, then, that our descriptive definitions of words –  what they really are to us – comprise more than mere features. Rather, they are expansive, innovative, holistic. They explode the limits of dictionary definitions.  With this in mind, we might try to imagine a word as something like a spinning, shimmering ball of inferences. Such a conception of words belongs to a new world, which for us has just been coming into view – a world of infinite connections – not a place which is reduced to features and components which are the mechanical world of Newton and the past. Planets and mountains, cutlets and cats, apartments and karma, all intertwine.

We play a dangerous game with our reductions, slashing meanings off words this side and that to reach a hard, prescriptive core. And so we separate science from outcomes, politics from poverty, business from ecology.  On our university campuses, moreover, we put the humanities over there, the sciences over here.  At stake is not merely the definition of a planet, but the definition of definitions, and the whole way in which we look at our world, our emotions not excluded.

This is why Pluto is a planet.