In general linguistic terminology, the label ‘perfect’ is ‘used of an action, etc. considered as a completed whole’ (Matthews 1997: 271). Although English has -en has traditionally been labelled ‘perfect’, this is not an appropriate label. Indeed, in the last sentence you read, has . . . been labelled does not imply that this labelling is a thing of the past; it is, indeed, still very much in vogue.

Has -en is used of an event or state which commenced previous to the time of speaking. Depending on the verb used and accompanying adverb (if any),it may or may not be continuing up to the present. I employ the label ‘previous’ (pr) for has -en, as against ‘actual’ (ac) for -s (both are perfective present).

Consider the verb live, first with actual perfective and actual imperfective present:

(19pe) Roy lives in New York

(19im) Roy is living in New York (now)

Sentence (19pe) implies that Roy’s living in New York is a long-standing situation. In contrast, the imperfective is -ing in (19im) indicates that he has recently relocated to the city, as a dynamic activity. Typically an adverb such as now will be included.

Now consider the corresponding sentences with actual and previous choices within perfective present:

(20ac) Roy lives in New York

(20pr) Roy has lived in New York

(20pr’) Roy has lived in New York since his wife died/for ten years

Whereas (20ac) describes an actual present state, (20pr) states that he began to live in New York some time previous to the present. When there is no time adverb in the sentence, the implication is that he no longer lives there (this is a ‘perfect’ meaning). But with the addition of an adverb specifying a period of time, which indicates when his living in New York commenced (when his wife died, or ten years ago), the sentence states that he is still living there (this is not a ‘perfect’ meaning).

Even without a time adverb, a has -en sentence may refer to some activity which began at a previous time and continues up to (and quite likely beyond) the present. Suppose that I turn a street corner and come across two louts fighting, with a friend of mine standing close by. I could ask him Did you see what happened? and receive the reply, with my friend’s eyes still on the battle:

(21) I’ve watched it all

Suppose that a dramatist’s mother is at the opening night of her son’s new play. During the interval she remarks to him: I have enjoyed it; the have -en indicates that her enjoyment has extended from the beginning of the play up to that point.

With a sentence that refers to a completed process, has -en implies that it just happened. For example:

(22) The ice has melted

(23) He has discovered gold

These sentences carry the implication that the melting and the discovery took place in the very recent past. There is, however, no such implication with a verb which does not describe a completed process, as in:

(24) I have enjoyed Handel’s ‘Messiah’ (I saw it performed only once, ten years ago)

(25) I have believed in the Christian god (I believed in this god for about six months when I was fourteen, over fifty years ago)

The perfective/imperfective and actual/previous parameters freely interact. Virtually any verb or copula type may take has -en. There are restrictions as to whether a verb may occur with imperfective is -ing; it must be able to describe an evolving activity. A verb which permits is -ing may augment this with has -en. For example:

(26) I have been waiting for you (for three hours/a long time/since three o’clock)

Even when the time adverb is omitted from (26), the stretch of time I have been waiting, which began at some previous time, is understood to extend up to the moment of speaking.

Examples (15)-(17) each describe a dynamic activity, extended in time. Adding has -en indicates that the activity began at a time previous to the present and in each example there is a clear implication that it continues to the present.

(15pr-im) I’ve been thinking about [whether you should go] (ever since we got news of the civil unrest in your planned destination)

(16’) He normally drives a Volvo but this week he’s been driving a Volkswagen (ever since he crashed the Volvo)

(17’) John has been having a series of injections (all this week)

A temporal clause commencing with after having . . . -en may omit the after, as in (After) having brushed her teeth, Mary went to bed.