Why is a raven like a writing desk?
"Mad Hatter: 'Why is a raven like a writing-desk?'
'Have you guessed the riddle yet?' the Hatter said, turning to Alice again.
'No, I give it up,' Alice replied: 'What’s the answer?'
'I haven’t the slightest idea,' said the Hatter"
We never find out in the book the answer, and we don't know if there actually is an answer (from the book).
However, the riddle must have come from somewhere, and maybe it does have an answer, or maybe it symbolizes something.
Does it have an answer?
Yes, but one from the author or just any answer? The answers below contain a wide range of *possible* answers written post-facto by other authors.
@Beastly There isn't a *definite* answer. This question has been discussed a LOT by various literary critics over the years, and you're not going to get anything much better than my answer (plus more possibilities if you want them).
@Randal'Thor - There is a definite answer. That answer is (in the author's own words) that **there is no answer**
Because they both can have caws/cause for thoughts. A raven has thoughts in caws. A desk gives cause for thoughts.
It's open to many possible interpretations. Lewis Carroll intended it to be little more than a joke, with no real answer, but his readers bugged him so much that eventually he proposed an answer, which he included in the preface to the 1896 (some sources say 1897) edition of Alice in Wonderland:
Enquiries have been so often addressed to me, as to whether any answer to the Hatter's Riddle can be imagined, that I may as well put on record here what seems to me to be a fairly appropriate answer, viz: 'Because it can produce a few notes, tho they are very flat; and it is never put with the wrong end in front!' This, however, is merely an afterthought; the Riddle, as originally invented, had no answer at all.
(source for this quote; emphasis mine)
It's important to note that:
Originally, it was supposed to be a little funnier than that. Carroll spelled 'never,' as 'nevar' — 'raven' spelled backwards — but a proofreader erased the inverted pun before it was published.
But since the riddle as originally written was intended to have no answer, the solution provided by Carroll in later years is no more canonical than any other. So an answer to your question would be incomplete without mentioning some of the many other solutions which have been proposed over the years, several of which are (IMHO) better than Carroll's:
Because Poe wrote on both.
–- Sam Loyd, Cyclopedia of Puzzles (1914)
Because it slopes with a flap.
–- Cyril Pearson, Twentieth Century Standard Puzzle Book
Because there is a b in both, and because there is an n in neither.
–- Aldous Huxley, “Ravens and Writing Desks”, Vanity Fair, September 1928
Because it bodes ill for owed bills.
–- Francis Huxley, The Raven and the Writing Desk (1976)
Because one has flapping fits and the other has fitting flaps.
–- Peter Veale
Because one is good for writing books and the other better for biting rooks.
–- George Simmers
Because a writing desk is a rest for pens and a raven is a pest for wrens.
–- Tony Weston
(the above bullet points taken from this blog post)