If a tree falls in the forest and there is no one to hear it, it does not make a
When the proverbial tree falls in the forest, it vibrates creating sound waves that will, under normal conditions, cause a sound-experience as of a crashing tree in the mind of any normal hearer who is within range. There are plenty of vibrations and sound waves, and conditionas are ideal, but alas, there is no one around in that isolated forest, not even a wood-pixie, to have any sound-experiences at all.
Was there a sound nevertheless? I say yes. "Sound" in its primary, objective use picks out, roughly, whatever features underlie the objective auditory properties we take ourself to perceive in the world outside us--vibration-events in the tree, more or less, or perhaps the soundwaves they cause. When I say that I hear the resplendent sound of that trumpet, I take myself to be representing a feature of the trumpet (or it's current activity) not a feature of my mind, though I recognize that my auditory capacities are required to accomplish this representation. Cases of auditory illusion (or hallucination) only support this objective use: if I hear voices where there are none, we call it illusion precisely because I am misrepresenting the world as containing sounds that it doesn't.
But then what am I hearing? They sure sound like sounds. A difficult question to be sure, and I think it reveals a minority subjective use according to which we use "sound" to pick out, roughly, qualitative features of a given sound-experience. These can exist (and so can "sounds" in this subjective snese) even when, as in illusion, they are brought about by something other than the objective sounds that normally cause them--by a drug, for example, or a brisk rapping on the ears. But this really is, in my view, a less common and perhaps even misguided usage.
So, yes, the tree does make a sound even when no one hears it. (And if you're convinced by this, I'd like to share with you some intersting ideas I have about the number of angels that can dance on the head of a pin.)
It's difficult to link these considerations about sound to Schrodinger's cat. And there's no reason, in any case, why our theory of sound should parallel our understanding of quantum mechanics. Nevertheless, the thought there is that a certain orthodox interpretation of quantum mechanics won't allow us to say that certain micro-physical state of affairs are completely determined independently of (and in advance of) certain measurements or observations of these states. And the poor cat is meant dramatically to amplify this weirdness. If this is the best way to understand quantum reality, then it doesn't contain the type of independence between observed and observer that I claim holds between sounds and sound-experiences. A competing "many-worlds" interpreation of quantum mechanics is more akin to my view of sounds. The cat, on this view, is determinately alive in one "world" and dead in another, and this is so independently of the behavior of my different counterparts who discover different pieces of news in their respective worlds. But I have a difficult time with this theory; and you can take that from someone who believes that vastly more sounds have been made than heard.