Consider these examples:
By now the desk should be looking significantly tidier!
By now, the failure of regulators to contain dangerous forces should be well accepted.
By now I own some forty copies of the magazine.
By now the blue of twilight is glowing.
He used leverage, but by now applied concerted discipline to contain his risks.
I wonder if I can use "now" instead of "by now" to convey the same meaning.
I would think "by now" refers to a moment until now, but why not use past tense or present perfect tense in the these examples?
Best Answer
Part I - by now vs now These sentences may all be uttered with bare now, no by, but they will mean something slightly different.
Bare now simply describes the present state. By now focuses on the process by which the present state was achieved. It emphasizes change of state over time, in the course of the process, and it leaves open the possibility that the process will continue in the future.
Part II - tense change A change from simple present→simple past changes only the time reference: you assert that the eventuality obtained in the past rather than the present. Now or by now have the same significance as in the present, but refer to a past rather than a present Reference Time: they might be replaced with (by) then.
5. is already in past tense. 3 and 4 are pretty simple: you just change the present-tense forms (3pr, 4pr) to past-tense forms (3pa, 4pa):
But the two with should are tricky, because that past-form should may represent either a realis or an irrealis. I'm going to cast these as reported speech so the time references are clearer.
With a realis, should is identical in the past tense, so if 1pr. means “he is confident that the desk now looks tidier”, the past realis version 1pa-r will mean “he was confident that the desk now looked tidier” and will be expressed this way:
But if 1. means “he feels the desk should look tidier than it does”, the past irrealis version 1pa-i will mean “he felt the desk should look tidier than it did” and will be expressed this way:
The corresponding versions of 2 are
Part III - perfect recast A change from simple present→present perfect is quite different. (Again, I’m going to skip #5, which is in the past tense rather than the present; if you find it presents issues distinct from those addressed here, I’ll be happy to address them in a separate question.) The two versions without modals have significantly different meanings than their simple present versions.
As for the two sentences with should, you know that these cannot be literally recast in the present perfect. There is no such thing as perfect modal, because modals are defective—they have no past participle to enter into a perfect construction. The closest you can get is a modal perfect, in which the modal takes a perfect construction as its complement:
I have already indicated what these signify in an irrealis context (see 1pa-i and 2pa-i, above). If the should bear a realis significance, you have the same problem as with 4prpf—you need to pin down the front end of the timespan.