Just in case you didn't know (and I'm sure you did) if you have fewer pints you have less beer. You cannot have fewer beer and you cannot drink less pints.
If you are talking about items that you can count - one, two, three, four - you use fewer (in mathematics this is called a discrete variable). If you are talking about an amount you use less. With that in mind, from the sullen quagmire of the Dear Dogberry page comes this query from Eleus:
The other day I wrote a comparison of Mozart and Schumann (not just for fun). The whole essay was coming together really well, except for one sentence that I just couldn't resolve.
I wanted to say something along these lines: "Schumann was born less than 20 years after the death of Mozart". But I had a sneaking suspicion that it should have been "fewer than 20 years", and it niggled at me for hours until I went back and re-wrote the paragraph so I didn't have to say it that way at all.
Still, I'm a bit befuddled.
I know that we say there is "less time" - but years are finite, aren't they, so surely it's "fewer years". What happens then if the years aren't whole years? For instance what if he was born 19 and a half years after Mozart - is that really "fewer"? - because it seems more of a continuum to me.
Or what if one person has 3 litres of water and someone else has only 2.9 litres of water. I know the second person has less liquid but do they really have fewer litres?
I've been thinking the issue over so much it's become obnubilated and I just can't straighten it out.
Am I making a simple thing complicated?
Well, Eleus, I think that in your wisdom you have pretty much answered your own question. It would be "less than a year" because, though a year is a discrete variable, the time that you are now subtracting from it is not, it is an amorphous amount. The same, I think, applies to twenty years.
This could not be said of "less than twenty people", which would be wrong because you could only subtract one person at a time from the crowd.
Just to be complicated. If, rather than using years, you were using markers of a year's passing (like winters) you would need to use to fewer. Schumann was born fewer than twenty winters after Mozart's death, but less than twenty years.
There's a Cowboy Junkies song about a long marriage that goes "It's been thirty summers that I've spent with him", meaning not that they spend winters apart, but that they've been married thirty years. Had their marriage been shorter, they would have spent fewer summers together. As Wordsworth put it:
Five years have passed; five summers, with the length
Of five long winters!
I hope that clears it up.
Incidentally, I love obnubilated, which, dear reader, means beclouded.
P.S. I'm sorry that this reply has taken so long, I am now back in England and clearing the backtwig (which is like a backlog, but smaller).