For All Intensive Purposes, This Is Not a Mistake
By the BrainSnail editorial team. How these articles are written and checked, and how to tell us when one is wrong.
Replacing an unfamiliar phrase with a similar sounding one that makes its own kind of sense is a specific and interesting error, distinct from simply getting a phrase wrong.
What distinguishes it
Somebody hears a phrase they do not fully know, and reproduces it as different words that sound nearly identical and that make sense given what the phrase means. Hearing that something is for all intents and purposes and reproducing it as for all intensive purposes qualifies, because intensive is plausible in context. The reasoning is visible and defensible, which is what separates this from a random mishearing. The name comes from a documented case of somebody writing egg corn for acorn, which is not unreasonable given what an acorn looks like.
The neighbouring categories
Several kinds of error look similar and differ in an important way:
- •A mondegreen mishears song lyrics and produces nonsense
- •A malapropism substitutes a wrong word that sounds similar and does not fit
- •A folk etymology reshapes a word and becomes the standard form
- •A spoonerism swaps initial sounds between words
- •This category alone produces a version that independently makes sense
- •Which is why it spreads and why it is hard to notice
Why they spread
The reason these persist is that they are not obviously wrong to anybody who has not seen the original in writing. A phrase encountered only in speech supplies no spelling, and the listener must guess at the words, choosing whichever parsing makes sense. If their guess is coherent, nothing ever corrects it, and they may use the phrase confidently for decades. Phrases containing an archaic word are especially vulnerable, since the original component is meaningless to a modern speaker while the substitute is not, so the substitution is an improvement from their point of view.
The ones people argue about
A handful of examples are contested in exactly the way the category predicts. Saying somebody has another think coming or another thing coming divides people sharply, and both versions have long histories. A damp squib and a damp squid, a moot point and a mute point, and shoo-in against shoe-in all generate the same arguments. What makes them interesting is that the substituted version is frequently more transparent than the original, since a squid is a familiar thing and a squib is not, so the reasoning behind the change is visible even to those who object to it.
When they win
The category is unstable at the edges because a sufficiently popular example simply becomes correct. Once a majority of speakers use a version, dictionaries record it, and the original becomes the curiosity. Several standard English words arrived exactly this way over the centuries, having been reshaped from something opaque into something analysable. The only difference between an error and an etymology is how many people made it and how long ago, which is why prescriptive objections to current examples sit awkwardly beside acceptance of older ones that went through the identical process.
The takeaway
Substituting a similar sounding phrase that independently makes sense differs from a mishearing, a malapropism or a spoonerism precisely because the result is defensible. They spread because a phrase heard and never read supplies no spelling, so a coherent guess is never corrected. Enough speakers making the same substitution turns it into the standard form, which is how several ordinary English words arrived.