In this metaphor is it correct to use "further" or "farther"?
That only kicks the can further/farther down the road.
Within the metaphor, the distance is physical, justifying the use of "farther". But since the road is not a literal road, the distance is metaphorical, justifying "further". Which is correct?
For your example, I suggest you go with your gut.
Further and Farther have been used interchangeably for years, even by the experts in English.
From Quick & Dirty Tips .com:
Wherever possible, use “farther” for physical distance and “further” for metaphorical, or figurative, distance. It's easy to remember because “farther” has the word “far” in it, and“far” obviously relates to physical distance.
Sometimes it's hard to decide whether you're talking about physical distance.
The good news is that in ambiguous cases it doesn't matter which word you choose. Although careful writers will try to stick with the distinction between “further” and “farther,” the _Oxford English Dictionary, Fowler's Modern English Usage_, and a number of other sources say that, in most cases, it's fine to use “further” and “farther” interchangeably, especially when the distinction isn't clear. People have been using them interchangeably for hundreds of years, and a few experts don't even follow the distinction.
