history - Why have the subjunctive and indicative converged in Modern English?

It is to me a curious fact that the subjunctive mood of verbs in English has so nearly disappeared in modern times. In fact, even the correct form and usage of the subjunctive in Modern English barely distinguishes itself from the indicative! In many regions and dialects, the subjunctive would appear to be entirely obsolete, replaced by the indicative in all cases. (Educated speakers, certainly in Britain at least, do however still make good use of it.)

The present subjunctive form in Modern English is (in almost all cases) virtually identical to the third-person plural present indicative (e.g. 'He were', 'She own'). This is markedly different from Old English, where the subjunctive form a form was much more easily noticeable. Even by the advent of Early Modern English in the 16th century, the subjunctive was already converging with the indicative.

Other Modern European languages, not only Romance ones such as French and Spanish, but Germanic languages related to English (e.g. Dutch/German) have a much more pronounced subjunctive form. From what I remember of my Classical Latin, word suffixes for a variety of tenses are hugely obvious in the subjunctive.

My question is: why is this convergence of the subjunctive and indicative so strongly the case in Modern English? Is it a general trend in other Germanic/Romance (or more generally Indo-European) languages? Why is its disappearance so much more apparent in English than other related languages?

Answer

I mentioned this in another question, but just because the morphological inflection is disappearing, that doesn't mean the subjunctive mood is actually disappearing from the language. Just like when most of our verbal inflection disappeared (now it's "I go", "you go", "we go", "they go"), that doesn't mean we lost verbs for first person singular and plural, 2nd person, and so on.

Nohat's short answer gives the main point — if 9 out of 10 times the form looks identical to a MUCH more common form, then over time things might converge and regularize. A linguist would call this "paradigm leveling". Less common words and structures tend to regularize faster than more common ones (which is why words like "to be" and "to have" are irregular in so many different languages). The subjunctive is rare and not that distinct in English, so it is in trouble.

We see the past subjunctive form only in "to be", but we see the present subjunctive in the third person singular form of any verb — it has no "s" at the end like the indicative form.

So, this is of course subjunctive:

If I were ten years younger... (often said "If I was...")

But this is subjunctive too:

So be it.

It's important that he arrive on time tomorrow.

There are a bunch of examples here that include this other kind of subjunctive. This is just anecdotal but I haven't noticed this one disappearing as much.

Is this a general trend in related languages? Well, in Swedish this seems to be happening. In German one subjunctive form is used all over the place, and the other is used pretty much just in newspapers and journalism in general, but it is at no risk of dying out (it has legal implications akin to those that make the word "allegedly" so important in English journalism).