Ambiguous sentences

Psychologists and others have used ambiguous images to cast light on the way that we perceive visual images, and many have a fascination for such puzzling pictures.

Duck-rabbit illusion, Wikimedia Commons.
Duck-rabbit illusion, Wikimedia Commons.

Here are two examples of well-phrased English sentences which are more than a match for any duck/rabbit.

I saw that gas can explode
– meaning either I saw that particular can of gas explode, or I saw that it was possible for gas to explode.

I saw her duck
– meaning either that I saw her crouch down, or that I saw her aquatic bird. Perhaps we also ought to allow I heard her rabbit to balance the duck/rabbit image. Aficionados of the classic British TV comedy Are You Being Served may also recall with giggles the relentless exploitation of ambiguities over Mrs Slocombe’s cat, which she always referred to as her “pussy”.

There are many other similar examples, including
Visiting relatives can be boring
Flying planes can be dangerous
This animal has four legs and flies
Kim saw the astronomer with the telescope
I know you like the back of my hand
I had forgotten how good beer tastes.

In contrast to those underspecified sentences, here is a notorious pair of very tightly specified sentences:

List the associates of each witness who speaks Spanish
List the associates of each witness who speak Spanish

Although differing only in the number of the final verb, they refer to quite different lists. In the first, with the verb in the singular, it can only refer to each witness, thus calls for a list of the associates of (each witness who speaks Spanish). In the second, with the verb in the plural, it can only refer to the associates, thus calls for a list of (the associates who speak Spanish) of each witness.

The title of Lynne Truss’s* prescriptive book on punctuation Eats, Shoots & Leaves is a good example of the tightness of specification on a single comma.

I acknowledge the late Ivan Sag and others for perpetrating and promoting these little puzzles.

* I feel it would be irreverent to deliberately use Trusss, Trusses, or Truss’, so will avoid doing so, however diachronically appropriate it might be.