One of the things we like to promote as the Speech Dudes is that the skills and knowledge that Speech Pathologists/Therapists learn can be put to use outside the field of Speech Pathology in general. To our way of thinking, that serves to encourage the rest of the world to recognize that SLPs are not just “twin-set and pearls” ladies who help people “speak correctly” but also talented individuals whose years of training and experience can be used to comment on and critique the broader topic of “human communication.”
Which brings me to the following sign and the Case of the Unauthorized U-turn.
As my wife and I were heading for dinner at a local brew pub, she noticed a car making a U-turn on a divided highway at a gap where this sign was present. “Oh,” she said, “Look at that. He’s not allowed to make a turn there.” At this point, the SLP in me kicked into gear.
“Well,” I replied, “that’s not necessarily true because the sign is lexically ambiguous.” Before you worry too much, we’ve been married for close on 35 years so she’s completely unsurprised when I use phrases like “lexically ambiguous” in a casual conversation. So when she asked “What do you mean,” it wasn’t for a definition of lexical ambiguity but for an explanation of the nature of the ambiguity.
I think the intent of the sign is to use the phrase “emergency and authorized” as an adjectival pre-modifier for vehicles with the and working simply as a coordinating conjunction along the lines of:
NOUN PHRASE [(ADJ <emergency + <and> + authorized>) + (NOUN <vehicle + s>)]
So the whole thing is a single noun phrase consisting of an adjective, a noun and an adverb. Fair enough.
However, you can also interpret it as TWO sentences , where the first uses the word emergency as a noun, which is then yoked by and to the second sentence, which is about “authorized vehicles.”
NOUN PHRASE [(NOUN <emergency>) + CONJ (and) + NOUN PHRASE [(ADJ + (NOUN )]
The adverbial element of only doesn’t really help because whether you choose the single- or two-sentence interpretation makes no difference. That’s why I have conveniently left it out of the analysis .
What makes it more ambiguous is that there is, in fact, an implied rather than actual subject to the sign, along the lines of “This gap in the road can be used for…” and so both the following interpretations would be fair game:
“This gap in the road can be used for an emergency” and;
“This gap can be used for authorized vehicles.”
In the event that the offender was stopped by the police, I would think that a smart lawyer could argue that is he/she was making a U-turn because there was a definable emergency (“I just got a call from my wife telling me she thought someone was skulking around in the yard”) and if that is true, then it was a legitimate maneuver.
The fundamental ambiguity stems from the fact that the word emergency can used both as a noun and an adjective but authorized can only be an adjective or a verb. So you can have both “an emergency situation” and “an authorized situation” but although you can have “I had an emergency” you can’t have *”I had an authorized.” On the other hand, you can have “The vehicle was authorized” but not *”The vehicle was emergency.”
Of course, one option is simply to use the following sign instead:
You’re welcome, Ohio Department of Transportation.
 I know I’m running a little fast and loose with the term sentence here but hopefully you understand the basic idea. For the purpose of the article, I’m adopting the fairly liberal definition of a sentence as “a group of words that express a single idea.”
 One of the challenges – for me – with a blog post is that for every sentence I write or word I use, I feel like I could write a separate paragraph on each. This is especially true when I make a statement that I think someone might want me to support by evidence. That’s not, in of itself, a bad thing because as a Speech Therapist I would want to be able to use a evidence-based approach to my practice. But the danger is that you get stuck in the infinite regression of “prove it” for everything you say. In fact, in the world of politics. that’s an actual tool you can use to prolong discussions to the point that nothing gets done. So you can say things like, “Despite what people believe, the average US citizen is 407,000 times more likely to be killed in a car accident than at the hands of a terrorist; or 6 times more likely to be killed by a shark” to which a supporter of travel bans from predominantly Muslim countries will respond, “And where did you get those figures?” So if you then say, “The National Safety Council and the National Center for Health Statistics report for 2013,” the next response is “How did they arrive at those numbers?” At this point, you begin to see where this is going and with each supporting statement and new “appeal to your sources” will be made. If you keep this up long enough, nothing changes.