Grammar experts use an odd standard when deciding what’s acceptable and what isn’t. They often argue that a word or phrase can be used in a certain way based on precedent: if it was used that way a long time ago, it must be OK now.

In other words, “If it’s old, it must be right.”

Imagine if we applied that faulty logic to the ancient belief that the sun revolved around the Earth. To paraphrase Tim Minchin in his song “White Wine in the Sun,” just because ideas are tenacious, that doesn’t mean they’re worthy.”

Two plus two doesn’t equal five just because someone added things up wrong a couple of thousand years ago. It was wrong then, and it’s wrong now. The Earth isn’t flat today because people used to think it was. Language is, to some extent, the same way. It’s not quite as clearcut as mathematics, and it does evolve, but that doesn’t mean there can’t be obvious right and wrong choices.

There are.

Even better, you can often tell what they are using a simple standard: Do they improve communication or make it worse?

Such is the case with the debate between “set foot” and the increasingly popular alternative, “step foot.” I can tell you right now, unequivocally, that the traditional “set foot” is correct, and “step foot” isn’t.

It’s not a popularity contest

One researcher noted in 2014 that “step foot” isn’t as old as “set foot.” And “set foot” is more widely used too. My Google search turned up some 20 million hits for “set foot” and “setting foot,” compared with about 6.5 million for the step and stepping alternatives — about three times as many. But the ugly step-child appears to be gaining ground: In that 2014 blog, “set foot in” registered more than five times as many hits as the lame alternative.

My favored usage is still comfortably ahead, but this isn’t a popularity contest. It’s about precise usage.

The term “stepping foot” is simply redundant.

To illustrate, I’ll substitute the hand for the foot. You can place or set your hand anywhere, but you never step with it. Stepping is only done with the foot — and that’s the key. To say you’re “stepping foot” somewhere is redundant. What else would you be stepping with? Your nose? Your rear end? Your jacket?

Each of these options is patently absurd. You can only step with a foot, so saying you’re “stepping foot” someplace is unnecessary and just plain silly. It’s like saying you’re hearing something with your ears. Who says that? Or you’re smelling something with your nose. I assume you weren’t sniffing with your small intestine.

Worse, “stepped foot” is simply improper usage. “Set” is a transitive verb: something you do to something else. “Step” is not. (The often-misunderstood lay/lie distinction functions the same way). You wouldn’t say, “I stepped my foot down” or “I stepped my foot in some horse manure.”

What about footsteps?

But doesn’t the term “footsteps” create the same problem? Why not just say “steps”? You can certainly do so and be clearly understood. But steps in this context is a noun, not a verb, and it can mean several things: the steps you take when walking, steps on a staircase/ladder, or figurative steps taken toward a goal.

There’s not much room for confusion here: If you say you hear steps behind you, no one’s going to conclude a ladder is following you, and if you say you’ve taken “concrete steps,” it’s unlikely that anyone will accuse you of stealing concrete steps from the high school stadium. (For one thing, they’re attached and too heavy; for another, why would you do so?)

Still, there are multiple uses for the noun “step,” so “footsteps” doesn’t bother me as much as a means of providing additional clarity. It passes the test of improving communication, if modestly so. The phrase “step foot,” on the other hand, does not.

“Set foot” is perfectly clear on its own. There’s no other way of using it, so there’s not even a hint of potential or farfetched ambiguity.

It’s therefore entirely pointless to use the redundant “step foot.”

Language can be silly and nonsensical at times. This is especially true of English, which has its share of ridiculous usages. But that doesn’t mean we should add to them necessarily. In this case, our course is clear: We should take a step back and set our collective foot firmly on the clearest, straightest path.

Stephen H. Provost is a former journalist, editor, and the author of more than 40 books. He steps softly and carries a big red pen.