Reuben asked:

As far as I can see, an event in space/ time does not rely upon the existence of an observer in order
to occur. Why can't the age-old "tree falling in the woods" question be answered with a simple Yes?

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Well, there's the Cartesian doubt... you can, after all, doubt pretty much anything you want, and the
only certainty, according to Descartes, at any rate, are your own experiences (and not whether they
relate to "reality"). Of course, Dennett has something to say about that in "Quining Qualia", where he
casts doubt on pretty much anything which is purely mental — any "feels" — except perhaps for
immediate experience... and how, after all, do you know what that is except through the memory of
the last instant? But then, Dennett has his own program. Even in Zen Buddhism (according to one
school, at any rate) there is doubt cast on the existence of the world when it is not observed. After all,
if our memories are doubtful (which is in fact the basis of Wittgenstein's private language argument,
and a lot of Dennett's objections to the classical understanding of qualia), then we have only others'
testimony to rely on. Now, what Dennett doesn't say is that we also can't trust written history and
others' testimony, for the same reasons... the history could either a) be misrecalled by the historians
and written incorrectly, or b) the historical texts themselves could have been altered unbeknownst to
anyone; and as far as others go, their memories are just as faulty as ours, right? So how dowe know
that the tree is still there when we aren't? You can assume, à la Berkeley, that it's in the mind of
god... but then you have to believe in a god.

Or, to put it another way, when you say, "an event in space/time", just what do you mean by
"space/time", anyway? Those are constructs, especially the space/time of the physicists, and even
the space/time of our perceptions, at least according to Kant. But if that's true, then how, ultimately,
can we rely on those constructs? Perhaps our memories are all that are backing them up. That is, we
get back to the inductive problem, and Hume's critique of it.

But I doseem to remember that the last time I tried walking through a wall, I bumped myself on it.
Perhaps I should try it again? But then I'd have to remember it — with all the attendant problems with
that — for the nexttime... unless I videotape it... but, there we are again, assuming that we can trust
the video not to have been tampered with, or just to have spontaneously acquired a sequence
showing me hitting a wall. Further, we still have the problem of induction: just because I couldn't do it
last time, so what?

Assumptions, assumptions. They all sound ridiculous, don't they. But try to refute them in any sense
stronger than "common" sense, and you'll find yourself in a bizarre tangle of philosophical positions
going back several thousand years, with no firm resolution in sight. Everyone from Descartes to
Dennett, Heidegger to Goodman, has had something to say (sometimes quite a bit) on this set of
questions. If all you want is common sense, why ask them? But if you want to go further than that,
you've got a few years of reading ahead of you.

Steven Ravett Brown

I'm not sure that the question is only about the existence of objects independent of their perception —
though it depends on how the age old question is phrased. It is often put as something like: "If a tree
falls in the woods and nobody hears it, does it make a sound?" In this version, we can grant realism,
and the independent existence of the tree, and still answer 'no'. This is because it depends on how
we define the word 'sound'. We can grant that the falling tree creates compression/rarefaction waves
in the air, but claim that a sound is not identical to these waves (though causally linked to them).
Rather, sound is the subjective experience caused by these waves in a conscious being — the
qualia, to use the technical word. If no-one is there to experience the qualia, then the sound doesn't
exist.

Tim Sprod