Duck or rabbit?

There used to be a standard disclaimer by non-fiction authors (once very common, now less so) in which, following thanks and acknowledgements to all those who in some way made their book possible through their scholarship or support, insist that 'any remaining errors are the author's own'.

How can the author be so sure that any errors are indeed his own? (Let's agree that female writers are incapable of such foolishness) By which I mean how can he possibly know that errors which remain ncorrected because they have not been identified are actually his?

My quibble is prompted by a a tweet from the Goldsmith shortlisted author Will Eaves:

Turing got the following bit of near-paradox past Wittgenstein without W noticing: "One can never know that one has not made a mistake."

It reminds me that I once had a short-lived habit of running some of Wittgenstein's more paradoxical aphorisms past my son (then aged six) and fondly recall this exchange:

"If a lion could speak we could not be able to understand him"

To which he replied in a growly voice:

"Yes we would. I'M HUNGRY! GRRRRR!"

He was good at cutting to the heart of a paradox (as children tend to be). When presented with Wittgenstein's famous image and asked "Is this a duck or a rabbit?" he replied "Yes. It's a duck or a rabbit."

The first appearance of this unattributed drawing was in the 23 October 1892 issue of Fliegende Blätter, a German humour magazine. It was captioned "Welche Thiere gleichen einander am meisten?" ("Which animals are most like each other?"), with "Kaninchen und Ente" ("Rabbit and Duck") written underneath.

Wittgenstein would later use it in his Philosophical Investigations, published posthumously in 1953, that a book confirms the old adage about philosophy making the complex simple and the simple complex. I am to Wittgenstein scholarship what Jeremy Clarkson is to - well, Wittgenstein scholarship, so my admiration is that of a muddy yokel gazing at a princess .