Question: “Jordan, a few years ago Ford Motor Co. used the tagline ‘Go Further.’ Would you please explain the correct use of ‘further’ vs. ‘farther?’ I would prefer to rely on the Grammar Guy rather than Corporate America for grammatical guidance. After all, the business world gave us ‘Lands’ End,’ ‘Eat Fresh’ and ‘Rethink Possible.’ Thank you for furthering the cause of good grammar.” – (Nancy Reichmann, Westfield)
Answer: Hi Nancy … to be fair, the business world also gave us Dodge Ram, which is a pretty fun little oxymoron to see roaming around town.
More to your point: There can be some ambiguity between whether “further” or “farther” is the correct choice, and this happens to be one of those occasions. Let’s talk about why.
Both “further” and “farther” have historically been used as the comparative form of “far,” meaning “at, to or by a greater distance.” The Oxford Dictionaries will tell you “further” and “farther” may be used interchangeably in that meaning, as they have been for hundreds of years.
“Further” has more uses, though. Unlike “farther,” which is limited to descriptions of actual distances, “further” is often used metaphorically or abstractly (ex. “to further a career”).
Because of this, many grammar guides – I include myself among them – suggest simplifying the situation by using “farther” in all contexts describing actual, physical distances, and “further” only for abstract or metaphorical uses. Otherwise you could end up like Ford Motor Co., where my response to their slogan is, “Go further what?”