Farthermore

In 1997, Isuzu introduced the new tagline “Go Farther.” Last year, Ford introduced the new tagline “Go Further.”  So now I’m hopelessly confused (not that I wasn’t already). When should a copywriter use farther vs. further?

As usual, my muse, Grammar Girl, has the answer: “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.”

I should have been satisfied with GGirl’s explanation. But since I’m a person perversely driven to go farther, further or both whether I’m driving a Ford or an Isuzu, I couldn’t stop myself from clicking on the next Google result. At that spiffy little link, Merriam-Webster (a.k.a. m-w.com) really had its grammar jammer on:

            “Farther and further have been used more or less interchangeably throughout most of their history, but currently they are showing signs of diverging. As adverbs they continue to be used interchangeably whenever spatial, temporal, or metaphorical distance is involved. But where there is no notion of distance, further is used.”

That’s way too temporal for me, m-w.com. The farther I get away from that definition the better.

Which brings us to the issue of using the words “farthermost” and “furthermore.” Oh, please, MaliaMania,” I hear you begging, “don’t go there, spatially, metaphorically or otherwise.”