In a viral tweet I saw a while ago, a BBC editor referenced a screen grab of a book by Mark Forsyth, according to which the order of adjectives in English language has to be: opinion-size- age-shape-colour-origin-material-purpose. “If you mess with that word order in the slightest you’ll sound like a maniac”, Forsyth warns in the extract. “It’s an odd thing that every English speaker uses that list, but almost none of us could write it out. And as size comes before colour, green great dragons can’t exist.”

The point of this post is to argue that the right order of adjectives is not merely an arbitrary choice, but can be understood in terms of a much simpler and more fundamental principle. And I hope to show you that the rule is far from odd or idiosyncratic, as I initially thought. It is simply a mechanism for efficient information processing that is meant to avoid ambiguities: English is read from left to right, and if the information is processed in that sequence, then one would subset the set of possible meanings, or things, implied by each word every time one reads a word; and the ordering of adjectives is to ensure that the meanings implied by this serial processing of information would convey the intended meaning of the sentence.

For example, in reading ”great green dragons”, one would sort the set of all possible things by greatness and take the subset of all ”great” things, and sort this subset of great things by colour and take all the things that are green, and finally take the subset sorted over greatness and colour and take the subset that consists of dragons. Thus, by the end of ”great green dragons”, the mind would possess a set of dragons taken from a set of green things, which in turn is taken from a set of great things.

Now consider ”green great dragons”. Following the same information processing mechanism described above, reading this phrase would amount to subsetting the set of all ”green” things to obtain only those that are ”great”, and finally selecting all the dragons from this list, if any are left. But none are left, I am afraid, for all hell has already broken lose! In subsetting the set of all ”green” things to keep only ”great” things, you have selected a strange species: something that is great within the set of green things. And, I am afraid I do not know what is it that you have selected, my friend. For if something is ”great” only amongst the subset of all the things that are green, is it still ”great”? And even if it is great in some sense, it is surely not great in the same sense in which it was when we said ”great green dragons”. In ”great green dragons” we put no limits on the great things we selected. They were unequivocally great. They were not great things selected from a set of some green things, or from a set of some not-so-green things, or from a set of some other idiotic things; they were great things, period.

To understand this more clearly, consider ”great knowledge”, and then consider ”green great knowledge” and ”great green knowledge”. This phrase is absurd/meaningless, for knowledge is not an object that can be coloured, and there is no such thing as blue or green knowledge, great or not. However, in reading ”great green knowledge”, one identifies the absurdity of the phrase when one reads ”blue knowledge”, which requires only sequential processing of information reading one pair of word at a time. However, in reading ”green great knowledge” the absurdity of the phrase does not become evident until one reads all three words, for neither pair in this phrase, ”green great” and ”great knowledge”, is necessarily absurd—one can in general have ”green great” things, and ”great knowledge”; it is only the whole phrase that is absurd, and recognising the absurdity of this phrase requires one to process information from right to left (from ”knowledge” to ”green”), which violates the sequential information processing mechanism.

In other words, because all green things can be made great, ”great green” is always meaningful, but because not all great things can be green, ”green great” is not necessarily meaningful, and the mind raises a flag when reading ”green great”. And ”green great” can be preferred to “great green” only when one means great things within the set of green things, which is a rather unusual things to speak of.

As far as I can tell, when you said ”green great dragons” what you meant were great dragons that happened to be green, but by saying ”green great things” all you have done is make a fool of yourself as a result of not paying sufficient attention to your fifth grade mathematics instructor, or whichever instructor taught you that operations are not commutative, i.e. operating A on B is not in general the same as operating B on A. In this particular context, sorting and subsetting over greatness first and then over colour is NOT the same as sorting and subsetting over colour first and then over greatness.1 When you selected ”great green dragons”, you ended up with dragons whose greenness could be in doubt, but there was no doubt about their greatness—their greatness was unconditional and knew no limits. But when you selected ”green great dragons” you ended up with with this strange species that you call dragon that is green beyond any reasonable doubt, but great? may be there are no great things in the set of green things; may be all green things are lame; and, at the very least, we had to process information from right to left (from ”dragons” to ”green”) to ensure that the phrase is meaningful (for if we had said ”knowledge” instead of ”dragons”, it wouldn’t be meaningful), violating the sanctity of sequential left-to-right information processing rule.

A reader cannot be guaranteed to understand what is it that you mean, if the text does not make sense when processed in a sequential manner from left to right, or more generally, if the rule for reading your text is not fixed a-priori, and may change from one phrase to another, without any fixed overarching rule. Sure, if you wanted to play devil’s advocate, you could argue that the author of ”green great dragons” intended the reader to be wiser than a mere robot that just browses sentences from left to right subsetting on every word it encounters. While it sounds reasonable when you put it like that, I am not entirely sure how it works in practice? How is a reader to decide exactly which phrases require this exalted level of wisdom, and which can be read like a robot? And while using an exalted level of wisdom that scans a text from left to right and then right to left, and possibly from top to bottom and bottom to top and in all such possible directions, may shed more light on the author’s true intentions, it can never reach the same level of certainty that can be achieve with a serial, formulaic processing of information based on rules that are fixed prior to reading the text.

Thus, it is not so much that ”green great dragons” cannot exist, it is that they are rather rare, and one is unlikely to encounter them, and when one does encounter them, the chances that they are really ”great green dragons” incorrectly labelled as ”green great dragons” is perhaps higher. It is for this reason that, practically speaking, ”green great dragons” do not exit, for even when they do, their existence is in serious doubt, and difficult to verify!