If a Tree Falls in the Forest (Pt. I)

In my classes we discuss the question of what we mean when we say that something is real. One aspect of the question we specifically address are sensory phenomena like color, fragrance, taste, sound, and so on.

Students often hold the view that these phenomena are objectively real, that sugar is sweet regardless of whether anyone ever tastes sugar, the sky would be blue even if there were never any living things on earth to see it, and a tree falling in the forest makes a sound whether or not there's anyone around to hear it.

But is it true that the phenomena of our senses are objectively real? Consider this description of how music is downloaded to a computer and then transferred to the listener's ear. The description illustrates the point that a piano, for example, doesn't actually make music. The music is made inside us by our brains/minds.

If there's no ear to capture the energy, no brain/mind complex to interpret that energy, there simply is no music.

Here's the article's description of the process of recording music for storage on a computer:

• The acoustic waves are picked up by a microphone and converted to electrical pulses.
• The pulses are converted by an analogue-to-digital (A-to-D) converter into numbers representing the frequencies and dynamics of the waveforms.
• The digital signals are compressed by an algorithm into a coded representation storable on an external medium, such as an MP3 file.
• The code is written as magnetic spots on a hard drive according to a storage algorithm that does not necessarily store them in physical order.
• On demand, a read head on the drive reconstructs the bits in their proper sequence and transmits them as electrical pulses to the central processor.
• The CPU relays the file to a router where the file is packetized and sent over the internet to a specified address, possibly traversing electrical wires, the air (radio transmissions), or space via an orbiting satellite along the way.
• The destination site’s router reassembles the packets into a file for storage on a “cloud” server such as YouTube or SoundCloud.
• The website embeds the file’s location in its local server, which you, the listener, access by means of touch, using a mouse, keypad, or touchscreen.
• Your computer’s sound card converts the digital signals into audio output through speakers.

Notice that at no point in this process is there the sensation of sound. Nothing is actually heard. The article's description stops here, but if we were to continue the bullet points we could say that,

• The audio output of the speakers consists of waves of energy traveling through the air like waves in a slinky.
• When these strike an ear they're transformed into an electrical impulse that travels along the auditory nerve.
• When that impulse reaches the brain it's converted, in some mysterious, marvelous way that no one understands into the sensation of music.

Until that final event happens there is no music, no sound at all, just electrochemical energy. The music is created by our brain/mind and the relevant sensory apparatus. Sound is a sensation, and without the involvement of a sense there can be no sensation. To insist that sound exists even though no one hears it is like insisting that pain exists even though no one feels it.

And if that's true of sound and pain it must be true of all of our other sensory experiences as well.

And if that's true what would the world be like if we had additional senses, or fewer senses? Why think that the world is exactly the way we perceive it to be, or, for that matter, anything at all like we perceive it to be?

One last question: Why do I refer to the brain/mind? Why not just assume that the brain is solely responsible for the sensations we experience? I'll consider that question tomorrow.