Adverb clause of comparison

What is the subordinate clause in this sentence? Which is the main clause?

"The higher you ascend, the colder it becomes."

The construction is referred to by the Cambridge Grammar of the English Language p1135-1137 as the correlative comparative construction. The first clause in the example given is the dependent one.

They surely could not be in coordination as it is not possible to switch their positions and maintain the same meaning.

The correlative comparative construction

What we refer to as the correlative comparative construction has two versions, illustrated in [39i–ii] respectively:

[39]

i

a. [The more] sanctions bite, [the worse] the violence becomes.

b. [The more conditions] I impose, [the less likely] is he to agree. [fronted version]

c. [The older] he gets, [the more cynical] he becomes.

ii

a.The violence becomes [worse] [the more] sanctions bite.

b.He is [less likely] to agree [the more] conditions I impose. [basic version]

c.He becomes [more cynical] [the older] he gets.

Both versions have paired – ‘correlative’ – comparative phrases (indicated by [brackets]).

Very much the more common version is the one shown in [i], but it is the other that is syntactically the more basic. The more sanctions bite is a subordinate clause functioning as adjunct, and likewise the more conditions I impose and the older he gets ; in [ii] they occupy the default position at the end of the matrix clause, whereas in [i] they occupy front position. The subordinate clause has the comparative phrase in front position in both versions, whereas the head clause has it fronted only when the whole subordinate clause is fronted. The comparative phrase begins with the when it is fronted; this is the modifier the discussed in §4.4.2 above. In the basic version it is possible but rare to have the in the non-fronted comparative phrase: The violence becomes the worse, the more sanctions bite.

The construction indicates parallel or proportional increase (or decrease, in the case of less) along the two scales expressed in the head and subordinate clauses. (The basic version marginally allows a verb such as increase instead of a syntactic comparative: The violence increases the more sanctions bite.) It can be approximately paraphrased by a construction in which the subordinate clause functions as complement to as:

[40]

i As sanctions bite more, so the violence becomes worse.

ii The violence becomes worse as sanctions bite more.

Because of this parallel movement along the two scales it is often possible to reverse the direction of dependency:

[41]

i The more we pay them, the harder they work.

ii The harder they work, the more we pay them.

In [i] the work clause is superordinate: the effort they put into their work increases as we pay them more. In [ii] it is the pay clause that is superordinate: the amount we pay them increases as they work harder. The two versions are not equivalent, however: for example, if they work harder each time we pay themmore, but sometimes work harder for other reasons and without getting more pay, then [i] is true but [ii] is false.

Syntactic evidence that the first clause in [39i] (the fronted version) and the second clause in [39ii] (the basic version) is subordinate to the other is provided by examples like:

[42]

i Won’t the violence become worse, the more the sanctions bite?

ii He is clearly the sort of person [who would be less likely to agree, the more conditions I impose].

Example [i] is a closed interrogative, and it is marked as such by subject–auxiliary inversion in the main clause. The bracketed part of [ii] is a relative clause, and again it is the superordinate clause whose structure is affected by relativisation. Note that such operations as those forming interrogatives and relatives can be performed on the basic version, not on the fronted version. The fronted version can be subordinated, but only in ways that simply involve adding the subordinators that or a relative phrase modifier such as in which case:

[43]

i He realised [that the longer he delayed the more difficult the task would be].

ii She may call an election, in which case the sooner we resolve these differences, the better our chances will be.