Are “Like” and “As” Interchangeable? It’s Complicated.

Which is correct: “It happened like I said it would” or “It happened as I said it would”? What about these: “It tasted like garbage” or “It tasted as garbage”?

If you picked the sentence with like in it both times, you’re not alone…but you’re only half right. Like and as are different words with different jobs, but people have been using like where they really need as for a LONG time.

So what’s the difference, and how can you tell which word you need in any given sentence?

The Rule

Technically speaking, like is a preposition, and as is a conjunction.

But that might sound like a bunch of unhelpful gobbledygook, so here’s a better way to say it: Like should be used when it comes before only a noun, and as/as if should be used when it comes before a clause.

Let’s take our first example:

It happened [like/as?] I said it would

What comes after like or as is “I said it would,” and that’s a clause. So, we need as:

It happened as I said it would.

Here’s the second example:

It tasted [like/as?] garbage

What comes after like or as is “garbage,” which is a noun. So, we need like:

It tasted like garbage.

Like‘s Villain Origin Story

The grammar books may restrict like to the role of a preposition, but the word has actually been used as a conjunction (alongside as) for over 600 years, per the Merriam-Webster Dictionary of English Usage. So why the separation now?

Although like was used as a conjunction for hundreds of years, it was only rarely observed in formal literature. It wasn’t until the nineteenth and twentieth centuries that we started to see like as a conjunction become more common. As the rate of its use increased, people started to take notice, and grammarians began to protest.

One of the earliest books to condemn like as a conjunction is Noah Webster’s Rudiments of English Grammar, which was published in 1790. As part of an eight-page list of “improper and vulgar expressions,” Webster included the sentence “He thinks like you do,” where like is used as a conjunction.

Around the early 1900s, sticklers, grammarians, and lexicographers all united to declare that it was wrong for like to be used in place of as or as if: They proclaimed that like is a preposition, not a conjunction.

A half-century later came this infamous 1950s cigarette commercial, which claimed that the product “tastes good, like a cigarette should.” Grammarians, language sticklers, and even popular media like The New Yorker protested this heinous use of like as a conjunction, claiming that the correct phrase would’ve been “tastes good, as a cigarette should.”

Newspapers reported on the controversy, it was discussed at serious length, and eventually the matter was settled by English usage books, which again proclaimed that like is a preposition, as is a conjunction, and the two should not be mixed.

I can’t help but wonder if the folks who created that 1950s cigarette jingle had been in elementary school when the whole like or as debate flared up in the early 1900s, and they were taking the opportunity to rebel against their teachers some 40 years later. 😂

Strictly Speaking…

Although usage has been mixed and the issue has been controversial for hundreds of years, there IS a rule to follow when it comes to like and as:

Like is a preposition, not a conjunction. As and as if are conjunctions to be used before clauses.

Like Is a Preposition (Followed by a Noun)

Use like as a preposition to introduce a comparison to another noun (or noun phrase):

That person looks just like you!

The words hit me like a train.

She felt like a ship lost at sea: wandering without purpose.

In all of those examples, like is the preposition and you, a train, and a ship lost at sea are all objects of the preposition.

As and As If Are Conjunctions (Followed by a Clause)

If the comparison is to a clause (not just a noun), you’ll need as or as if:

He ran as if he was truly frightened.

Please do as I say.

As you’ve probably noticed by now, this issue is far from simple.

In all of these examples, as or as if is a conjunction that introduces a clause: “he was truly frightened,” “I say,” and “you’ve probably noticed” are clauses, not just nouns.

Another option is as though, which is good for hypothetical situations:

You look as though you’ve seen a ghost.

He continued to work as though nothing had happened.

How To Tell the Difference and Pick the Right One

Here’s the simple rule, as stated by Amy Einsohn in The Copyeditor’s Handbook:

Use as, as if, or as though to express similarities or comparisons that involve a verb. Use like to express similarities or comparisons that involve only a noun.

Hypercorrection Strikes Again

Some folks are so nervous about using like in the wrong place that they just use as all the time. But as can be incorrect, too! When it’s followed by just a noun, like is the correct choice.

The Basenji is the size of a fox terrier and cleans itself as a cat.

“A cat” is a noun, so we need like before it:

The Basenji is the size of a fox terrier and cleans itself like a cat.

As we walked through the city, Frank observed that it smelled as rotten eggs.

“Rotten eggs” is a noun, so like is needed:

As we walked through the city, Frank observed that it smelled like rotten eggs.

When people are trying so hard to be careful that they end up overcorrecting and making the wrong choice in a different way, it’s called hypercorrection. This phenomenon is quite common, especially in formal situations when folks want to sound knowledgeable. Unfortunately, it usually comes from grammarians being so strict and adamant that people are terrified to misstep and thus make an entirely new mistake. As the Dictionary of English Usage puts it, the use of as as a preposition was “born in holy terror of using like.”

What questions do you have about like vs. as? Let me know in the comments, and I’ll find an answer for you!

Click here to learn the difference between then and than!

Sources:

• The Chicago Manual of Style. 17th ed. Chicago, IL: The University of Chicago Press, 2017.
• Ebbitt, D. R., and W. R. Ebbitt. Index to English. 8th ed. New York: Oxford University Press, 1990.
• Einsohn, Amy. The Copyeditor’s Handbook. 3rd ed. Berkeley and Los Angeles, California: Univ of California Pr, 2011.
• Merriam-Webster. Merriam-Webster’s Dictionary of English Usage. 14th ed. Taunton, MA: QuadGraphics, 2016.