What Is a Direct Object?
To talk about these two versions of substitute more easily, I need to introduce some vocabulary. If you’ve listened to this podcast for very long at all, you probably know what a direct object is. It’s the noun phrase that names the thing that receives the action of the verb. So for example, in the sentence I’m recording a podcast, the noun phrase a podcast functions as a direct object.
What Do Prepositional Phrases Do?
Now I want to introduce a term for the function of prepositional phrases. Often that function is to modify a verb or noun, but not always. For example, take the verb rely. If I were to tell you “I rely,” you’d be waiting for me to say something to finish the sentence. In addition, that something can’t just be a direct object: It’s not grammatical to say “I rely my friends.” The verb rely is looking for a prepositional phrase, and it can’t be just any prepositional phrase, either. It has begin with on or upon, as in “I rely on my friends.”
In contrast, if a prepositional phrase is modifying something, we typically have a choice of which preposition to use, or even whether to use a prepositional phrase at all. To illustrate, I could say “I slept in my bed,” “I slept on the couch,” “I slept under the stars,” “I slept with my cats,” or just “I slept,” plain and simple.
What Is an Oblique Object?
Another way that the prepositional phrase in I rely on my friends is not like a modifier is that in this sentence, the noun phrase my friends plays an essential role in the state of affairs that we’re talking about. If there’s any relying going on, it has to involve parties A and B, the relier and the relied-upon. For reasons like these, linguists sometimes say that prepositional phrases like these have the function of oblique object rather than modifier.
Just as some verbs take both a direct object and an indirect object, other verbs take both a direct object and an oblique object, such as blame: They blamed Squiggly for the delay. Another one is load, as in Aardvark loaded his cart with garden gnomes. And of course, there’s substitute.
Over the centuries, the verb substitute has been used with a variety of prepositions for its oblique object. Since the mid-17th century, substitute has been used with the preposition for, according to the Oxford English Dictionary, and that’s still the most common preposition to go with it. Further, for most of this time, the direct object has referred to the new thing, and the oblique object with for has referred to the old thing. That’s right: “substitute NEW for OLD”—like substitute something meatless for one chicken dish— is the historically older use.
An interesting fact about verbs that take both a direct and an oblique object is that often, there will be an alternative preposition that you can use, and when you do, you flip-flop the roles of these objects. Here’s a demonstration. In the sentence They blamed Squiggly for the delay, the direct object, Squiggly, has the role of the person who caused the problem, and the oblique object, for the delay, has the role of the problem. However, for rhetorical reasons, you may sometimes prefer to make the problem the direct object, and make the doofus who caused it the oblique object. You can do this if you change the preposition to on: They blamed the delay on Squiggly. You can do a similar thing with the verb load: Aardvark loaded his cart with garden gnomes, or Aardvark loaded garden gnomes onto his cart.
Like blame and load, substitute has an alternative preposition that lets you switch the roles of the the direct and oblique objects. According to the Oxford English Dictionary, sometime in the 19th century the preposition with came to serve this purpose, so that you could “substitute OLD with NEW.” Their earliest example is horrible, involving cruelty to a cat! So here it is:
I carried off a rabbit from the spit, and substituted it with the cat of my old aunt.
The role of “old” is played by the rabbit on the spit, and the role of “new” by the old aunt’s cat. This version of substitute has become more common in the last 200 years, and by now is fairly common, although not as common as “substitute NEW for OLD.”
The newest substitute, the one that has you substituting OLD for NEW, is from our example about the animal fats and vegetable oils: substitute saturated animal fats for healthier vegetable oils. This one swaps the roles of new and old without even using a different preposition from for. The earliest citation the OED has for this version of substitute is from back in 1978. The linguist David Denison gave it the name “reverse ‘substitute” in a 2009 paper. In a blog post that discusses reverse substitute, linguist Arnold Zwicky notes that it’s especially common in contexts involving food, which our animal-fats-and-vegetable-oils example certainly does.
Read Carefully When You See the Word “Substitute”
With these two structurally identical yet contradictory versions of substitute out there, how can we understand what speakers or writers mean when they use it? And how can we use it for maximum clarity?
When you read or hear substitute, pay close attention to context clues, especially if the topic is food, and don’t assume that the speaker or writer is using substitute in the same way that you do.
As for your own speaking and writing, here's my advice: First, since the oldest and still-most-common version is “substitute NEW for OLD,” use that one. Second, since “substitute OLD with NEW” has been around long enough to achieve some measure of acceptability, use it only if you have a compelling rhetorical reason to do so. Finally, avoid using “substitute OLD for NEW.”
Unfortunately, following these guidelines won’t eliminate confusion, because your audience may have grown up with “substitute OLD for NEW,” or even if they haven’t, they may be assuming you did. So I’m going to give some more practical but less satisfying advice: Be sure the context makes clear which roles the direct and oblique objects are playing, no matter which version of “substitute” you use. Or better yet, just use the word replace.
This podcast was written by Neal Whitman, who has a PhD in linguistics, blogs at LiteralMinded.Wordpress.com and is a regular columnist for the online resource Visual Thesaurus.
Denison, David. 2009. Argument structure. [paper on reversal of substitute] In Günter Rohdenburg & Julia Schlüter (eds.), One language, two grammars? Differences between British and American English, 149-65. Cambridge: Cambridge University Press. http://www.humanities.manchester.ac.uk/medialibrary/llc/files/david-denison/substitute_10_04_07.pdf
Zwicky, Arnold. Dec. 24, 2007. “Another reversal.” Post on Language Log. http://itre.cis.upenn.edu/~myl/languagelog/archives/005255.html
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