How to Settle an Argument

Here is a nice discussion paper by the Pacific Institute that takes on an issue and presents its viewpoint via facts rather than just claims and hot air:

Could walking be worse for the planet than driving? This startling idea has recently received coverage in New York Times blogs and beyond. ...
In his book, How to Live a Low-Carbon Life,6 Chris Goodall answers the question this way: “It makes more sense to drive than walk, if walking means you need to eat more to replace the energy lost.”7 Goodall—a proponent of reducing GHG emissions—comments that his intent is not to encourage driving, but rather, “to draw attention to the carbon intensity of modern food production, particularly of meat.” ...
However, it is misleading to suggest “it makes more sense to drive than walk, if walking means you need to eat more to replace the energy lost.” ... as shown by the estimated GHG emissions of the typical U.S. diet, walking—even for a group of four people—makes more sense than driving a given distance.

What I find interesting is that this corrective analysis results in a surprise for me, i.e. driving isn't that shockingly worse in terms of carbon footprint than such supposedly earth-friendly actions as walking in lieu of driving.