On the word PLANET

False color image of Pluto's heart (Image: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

It's been more than ten years since a mysterious cabal of astronomers known as the International Astronomical Union (IAU) reclassified Pluto under a newly devised category of dwarf planet and curators of natural history museums have long since adjusted their exhibits to reflect an eight-planet solar system, but even after all this time, it apparently doesn't take much to reignite the debate surrounding the issue. In March of this year, a PhD student from Johns Hopkins University presented a poster at the Lunar and Planetary Science Conference in Texas that was enough to make headlines on both sides of the Atlantic because it proposed a revised definition of the word planet that would return Pluto to the category along with a further hundred or so other objects from our solar system.

From a linguistic perspective, the Pluto debate raises some very interesting questions. For instance, why did anyone think that the IAU had the power to change the meaning of an English word as opposed to merely establishing a terminological convention for technical discourse within the field of astronomy? Why is the reclassification of Pluto frequently described as a demotion as if it's some kind of honor for a celestial body to be called a planet? And in what sense has the meaning of the word planet actually changed in the minds of speakers as opposed to what they believe about how many planets there are? The discussion around Pluto's reclassification reveals a lot about how people think about the nature of both language and science, so I think it's worth digging a little deeper into these issues.

An End to Pedantry: THAT vs. WHICH

I've used this blog on a number of occasions to debunk rules that are widely believed to represent 'proper' educated usage but which have very little basis in reality. I have for instance argued that data is not in fact a plural, that tomatoes aren't really fruit outside of botanical circles, and that there is no good reason to use an rather than a before words beginning with h. I'm far from alone in writing about these imaginary rules but I occasionally feel I can provide a slightly different perspective on them. After encountering some of my posts on these issues, one of my readers asked me to elaborate on what I meant by this:

The only standard by which we can judge the use of a word to be correct or not is whether it conforms to the conventions used by members of the speech community in the particular context in which it is being used. [On falling apples and whether tomatoes really are fruit, Oct 16, 2013]

In particular, this reader was interested in what I thought about the alleged rule for when to use that and which, and whether I think it actually matters whether we follow such rules if our meaning is likely to be understood in any case. What follows is a slightly edited version of the response I gave this reader by email, which I hope clarifies my position.

Stop telling people DATA is plural

The word data is almost universally used as a singular mass noun in English except among many professional writers and academics who insist that it is the plural of datum, a word that is almost non-existent in English outside discussions of whether data is a plural. The reason usually cited for treating data as a plural is that it was a plural in Latin, which is true but irrelevant since grammatical changes often occur when words are borrowed from one language to another. A perfectly analogous example is the word spaghetti which is a plural count noun in Italian but very clearly a mass noun in English, which is why native speakers of English say This spaghetti is cooked and not These spaghetti are cooked.

On falling apples and whether tomatoes really are fruit

Imagine a film of an apple accelerating toward the ground under the influence of gravity. If we played this film backwards, what would we see? It may seem odd, but a physicist will tell us that when the film is played backwards, the apple will continue to accelerate downwards! Regardless of whether the film is played forwards or backwards, the apple will accelerate downwards.

It is because physicists use the word accelerate with a slightly different meaning to the one in everyday use that an otherwise trivial fact about the universe can be cast as such a curious statement.

Articles: A vs. AN and THE vs. THE

A versus AN
When learning a second language, people usually learn the written form at the same time as the spoken form. With English, this can be confusing because the spelling is very irregular. This is especially true for the rule about when to use a versus an, but if phrased in terms of pronunciation rather than spelling, the rule is extremely simple:

RULE: Use a before words beginning with a consonant sound and an before words beginning with a vowel sound.

The spelling often agrees with the phonetic rule, as in the following example:

• a cat
• an old cat

But the spelling isn't always so kind:

• a university (because university begins with the y sound of youth)
• an umbrella (because umbrella begins with the u sound of up)
• a xylophone (because xylophone begins with the z sound of zoo)
• an x-ray (because x-ray begins with the e sound of extra)
• a hat (because the h is pronounced)
• an hour (because the h is silent)

The rule is about pronunciation rather than spelling, so the rule still holds perfectly in these examples, even if the spelling is unhelpful. If you know how to pronounce the next word, you'll always know whether to use a or an. Of course, for speakers of languages like Italian and French who have trouble hearing the h sound, this isn't so simple.

Note that there are a few people who believe that an should be used before certain words that begin with an h sound in modern English, and consider this 'proper' educated usage. The most common example of this occurs with the word historic:

• an historic event (rare usage)

The belief that this is grammatically correct is probably due to another unhelpful effect of spelling. The reason we can find 'an historic' written in old texts is that there was a time when the h of historic was silent in many people's speech. It's like the word herb in modern varieties of English. Some people pronounce the h and some don't. Those who pronounce the h write 'a herb', and those who don't pronounce the h write 'an herb'. Text preserves the spelling, but not the pronunciation that goes along with it, so after the pronunciation of historic settled on its modern form, people who saw 'an historic' written in older texts probably mistook this for a rule that applied to modern pronunciation.

In general, if native speakers have to be taught a rule that doesn't come naturally, there is probably something fishy about the rule. Misguided rules of this kind are almost not worth mentioning, except that people benefit from an awareness of them when they, for example, end up working for people who believe them.

THE versus THE
Like a, the pronunciation of the varies depending on whether the next word begins with a vowel or consonant sound. Before a word beginning with a consonant sound, the vowel of the is usually reduced to what's called a schwa, represented by the ə symbol in the International Phonetic Alphabet:

• the cat (pronounced ['ðə] with a short middle vowel)
• the old cat (pronounced ['ði] to rhyme with bee)

This is one of those details that native speakers almost never notice about their own language (again probably because it's not reflected in the spelling) and which they never need to be taught.