A couple of months ago, Rentz and Lentz at the Bcomm Teacher Xchange blog were kind enough to include one of my posts in their list of resources for learning how to diagram sentences. However, they express their preference for Reed-Kellogg diagrams over tree diagrams:
This blog post illustrates the differences between the Reed-Kellogg diagram and tree diagram methods for diagramming sentences. I prefer the Reed-Kellogg method. I know linguists prefer tree diagrams for their precision and more nuanced representation of sentence structures, but I’m not a linguist. I just want a visually accessible way for students to look at sentences, and (at least for me) the left-right reading orientation of the Reed-Kellogg diagram presents sentence structures more clearly than the top-down reading orientation of the tree diagram.
I’ll respond to their two reasons. First, it’s true that if you’re a linguist, you probably prefer tree diagrams to Reed-Kellogg diagrams. It’s also true that if you’re a cat, you prefer meat to vegetables. But if you’re not a cat, that doesn’t mean you prefer vegetables to meat. Case in point: my son Doug, who is not a cat, yet still likes his pizza with pepperoni and bacon when he can get it, and will pick off any peppers or onions. Likewise, you don’t have to be a linguist to like tree diagrams (if you like diagrams at all). I respect Rentz and Lentz’s preference for Reed-Kellogg diagrams, but dispute their non-linguisthood as a valid reason for the preference.
As for the “left-right reading orientation of the Reed-Kellogg diagram”, I’m afraid I don’t understand. One of the advantages of tree diagrams is that they preserve the linear order of an utterance. Reed-Kellogg diagrams use a mixture of left-right and top-down orientations, and if you don’t know the original sentence that is being diagrammed, you can’t always get back to it by reading off a Reed-Kellogg diagram. If you don’t believe me, check out this Reed-Kellogg diagram of the opening sentence from the Declaration of Independence, and then compare it to this tree diagram of the same sentence (you’ll need to use the magnifying-glass icon). Both diagrams are big and unwieldy, but only the tree diagram lets you read back the original sentence in unwavering left-to-right order.
This willingness to undo a sentence’s linear order to get at its structure shows up especially in Reed-Kellogg diagrams of interrogatives. An interrogative like Do you like cats? in a Reed-Kellogg diagram is indistinguishable from the emphatic You do like cats!, because subject-auxiliary inversion (e.g. Do you) is ignored.
Also, wh elements are always left in situ in Reed-Kellogg diagrams. That is, a sentence like What did you see? is diagrammed as if it were the question Did you see what? — or more accurately, as if it were You did see what?, what with the undoing of the subject-auxiliary inversion in Did you. That would be the question you might ask someone if they said to you, “I did see it!” and you didn’t know what the heck they were talking about.
There are even diagrams in which the combination of undoing subject-auxiliary inversion and leaving all wh items in situ collapse even more sentences into one representation. Take the sentence
Brynn will say who stole the cookies.
In a Reed-Kellogg diagram, but it looks like this:
We already know this will be indistinguishable from Will Brynn say who stole the cookies?, but there’s more. This is also the diagram for the interrogative sentence
Who will Brynn say stole the cookies?
In English, the who in these sentences is placed at the front of whichever clause is a question. If the question is about who stole the cookies, the who stays at the front of stole the cookies. If the question is about whom Brynn will accuse, the who goes in front of will Brynn say. But when you diagram it in situ, you don’t know which sentence you’re dealing with, and the semantic difference is more than just whether you’re asking about or stating the same proposition. In a language like Chinese, where all wh items really are in situ, the ambiguity of this diagram would be excusable, because the actual sentence would be ambiguous, too — but we’re diagramming English, not Chinese.
In fact, the above diagram is even the same as the one for …who Brynn will say stole the cookies, but we can cut a little slack here, since this is a subordinate clause, not a complete sentence. A Reed-Kellogg diagram would have to connect situate this clause within a larger one; for example, Fenster knows who Brynn will say stole the cookies.
For comparison, here’s how Brynn will say who stole the cookies and Who will Brynn say stole the cookies? look in tree diagrams (click to embiggen):
It’s worth noting that only the first of these four English sentences can be read off the diagram left-to-right.
A couple of other reasons I prefer tree diagrams can be seen in the diagrams in this post. First, it’s easier to collapse tree diagrams into triangles to hide the details. In the Reed-Kellogg diagram, even though I wasn’t interested in the internal structure of the verb phrase stole the cookies, I had to diagram it out, right down to hanging the the underneath cookies. In the tree diagram, I just took it down to the level of VP and left that phrase in a triangle of its own. Second, tree diagrams let you diagram a phrase without insisting that you diagram the entire sentence it came from. If I wanted to diagram just the structure of the predicate stole the cookies, I could do that easily with a tree diagram, whereas a Reed-Kellogg diagram would look incomplete with a predicate on one side of the vertical bar and no subject on the other side.
I’m not saying that tree diagrams always have it over Reed-Kellogg ones. For some sentences, neither kind has an advantage, and for some, Reed-Kellogg might even have an advantage. For example, Reed-Kellogg diagrams do a better job than tree diagrams of showing the unity of phrasal verbs such as throw away when they wrap around a direct object. For many sentences, though, especially the kind that syntacticians think about and traditional grammarians tend to overlook, tree diagrams are the way to go.