Presidential candidate and former Rhode Island Gov. Lincoln Chafee has promised he will switch the United States to the metric system in the exceedingly unlikely event he ends up in the White House. While the idea may help him among the Europhile segments of the Democratic base, it’s a truly terrible one. Indeed, the forced metrication Chafee seems to want would be intrusive, expensive and counterproductive.

To start with, Americans already do use the metric system – formally, the International System of Units, or SI – where it has obvious benefits. The metric system is nearly universal in the laboratory sciences, nutrition, pharmaceuticals and many areas of engineering (although measurements of torque and ballistics still commonly make use of the foot-pound of force, rather than the joule.) The law, through government departments of weights and measures, defines customary units like the foot, the pound and the gallon in terms of meters, kilograms and liters. Americans regularly buy two-liter bottles of soda and take part in 5K races.

An all-out conversion to metric, on the other hand, would require enormous and costly government intrusion. It would mean legal prohibitions on the use of traditional measures in trade, fining or arresting butchers who failed to sell meat by the kilo, or housing agents who listed apartment by any measure other than the square meter. This quickly could get ugly and intrusive: U.K. shopkeepers have even faced potential jail time for weighing goods in pounds rather than kilos.

Then, there’s the cost. The modifications needed to make the switch to metric almost certainly would consume billions of both public and private dollars. The bill to replace the markers every tenth of a mile on all 47,000 miles of interstate highway would, by itself, likely top $1 billion.

But perhaps most importantly, the metric system isn’t actually that useful for many of the things ordinary people actually measure day-to-day. In the Fahrenheit system, the range of 0 to 100 degrees pretty well covers normal outdoor temperatures one can expect to face (unless one is unfortunate enough to live in Barrow, Alaska, or Phoenix). In Celsius, that same range would be covered by roughly -20 to 40.

Carpenters and other craftsmen could tell you that feet and inches are actually more practical for their purposes than their metric equivalents. The 12 inches in a foot and 36 in a yard can evenly be divided by three, to make a triangle, or by four, to make a square. And we already live in a world based on these traditional measures. If one is out shopping for rugs, how is it helpful to redefine a 10×10 room as 3.048 by 3.048 meters?

Birthed in the French Revolution, the metric system was based, initially, on inaccurate 18th century measurements of the earth’s circumference. It is no more or less “scientific” than the traditional measures based on human body size and longstanding experience. It’s a testament to American common sense that we’ve avoided trying to force people to use it. But then, common sense has never been Lincoln Chafee’s strong suit.