Why is the present continuous used in English so often in comparison to the simple present?
For example
I eat
is possible, but the preferred way
I am eating
meaning roughly the same thing, is much more complicated.
In most languages, the simple present is the standard form. But in English, the more complicated form is favored.
Why has the more wordy present continuous mostly displaced a simpler form verb?
In English, 'I eat' is not actually a present tense, as such. The sentence :
I eat.
only conveys the concept of a state of activity. It is something I do, as part of my existence, throughout my lifetime.
I eat bread, I do not eat chicken ...
conveys a facet of my existence, an attribute of my humanity.
I am eating ...
is a true present tense. I am eating, now, presently.
Even if I say :
I am eating white bread this week and brown bread next week ...
it is still a present activity.
In my view, "I eat" can almost be regarded as an infinitive (in English).
If I may, I'm going to cite the British Council (and this specific page).
Present continuous is used:
→ for something that is happening at the moment of speaking
→for something which is happening before and after a given time (At eight o’clock we are usually having breakfast)
→ for something which we think is temporary (I’m working in London for the next two weeks.)
→ for something which is new and contrasts with a previous state (These days most people are using email instead of writing letters.)
→ to show that something is changing, growing or developing (The children are growing quickly.)
→ for something which happens again and again: (He’s always laughing.)
→ for something which has been arranged or planned (I am going to the city this afternoon)
Using "I eat" does not clearly carry a meaning of "I am doing the action of eating".
The simple answer is this: where many other languages require the listener or reader to establish from context whether the message originator is specifying he is currently engaging in that activity or that, generally, he does but may or may not be doing so now ("Je conduis" tells you nothing about whether I simply know how to drive, or whether I am driving right this second), English has evolved to allow the distinction. I think the distinction is a valuable one, even if it makes English harder to learn for native speakers of other languages.
I think it has to do with the way the language functions itself. On the other hand, present continuous is often used to talk about an action that´s taking place at the moment. There are other cases in which these could also be seen: How are you doing?, for instance. It´s true that more than ever before, there´s been a tendency to choose the longer form, but I think it´s idiomatic...
