Einstein's Riddle

Michael DeBusk m_debusk at deja.com
Mon Mar 12 09:18:13 CET 2001

Gregory Jorgensen wrote:

> We have no evidence that any of the five owns fish.

I know very little about transformational grammar, but I've picked up
enough to respond to this. There's a thing called "presupposition" at
play here.

A presupposition is an idea one has to pre-suppose so one can make sense
of a given sentence. For example, the sentence "tell the dog to get off
the sofa" contains presuppositions that such a thing as a dog exists,
such a thing as a sofa exists, that both the dog and the sofa exist in
such a way that dogs can be on sofas, that dogs can obey commands...
even that the speaker believes that the listener speaks and understands
English. All the things native speakers of a language intuitively know
when they go through the process of understanding a sentence, in other

The question "Who owns the fish?" contains a linguistic presupposition
indicating *someone* owns a fish; the question is not whether, but whom.
That presupposition is the evidence.

If the question was "Does someone own a fish?" one could then assert
there was no available information.

Someone else in the thread pointed out the problems involved in
translating the puzzle to other languages. I imagine that would create
some roadblocks, because the structure of presuppositions would be
different in each.

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