Epistemology

[StewartP]

My apologies for the long cut and paste. It is from Robert Persig's hippy manefesto "Zen & The Art OF Motorcycle Maintenance" One of my all time favorite books, and I hate hippies.

This particular passage exited me a lot when I first read it. The concepts are probably old hat to cunning philosophers like you but it explained things nicely for me.

Kant says there are aspects of reality which are not supplied immediately by the senses. These he calls a priori. An example of a priori knowledge is "time." You don't see time. Neither do you hear it, smell it, taste it or touch it. It isn't present in the sense data as they are received. Time is what Kant calls an "intuition," which the mind must supply as it receives the sense data.

The same is true of space. Unless we apply the concepts of space and time to the impressions we receive, the world is unintelligible, just a kaleidoscopic jumble of colors and patterns and noises and smells and pain and tastes without meaning. We sense objects in a certain way because of our application of a priori intuitions such as space and time, but we do not create these objects out of our imagination, as pure philosophical idealists would maintain. The forms of space and time are applied to data as they are received from the object producing them. The a priori concepts have their origins in human nature so that they're neither caused by the sensed object nor bring it into being, but provide a kind of screening function for what sense data we will accept. When our eyes blink, for example, our sense data tell us that the world has disappeared. But this is screened out and never gets to our consciousness because we have in our minds an a priori concept that the world has continuity. What we think of as reality is a continuous synthesis of elements from a fixed hierarchy of a priori concepts and the ever changing data of the senses. Now stop and apply some of the concepts Kant has put forth to this strange machine, this creation that's been bearing us along through time and space. See our relation to it now, as Kant reveals it to us.

Hume has been saying, in effect, that everything I know about this motorcycle comes to me through my senses. It has to be. There's no other way. If I say it's made of metal and other substances, he asks, What's metal? If I answer that metal's hard and shiny and cold to the touch and deforms without breaking under blows from a harder material, Hume says those are all sights and sounds and touch. There's no substance. Tell me what metal is apart from these sensations. Then, of course, I'm stuck.

But if there's no substance, what can we say about the sense data we receive? If I hold my head to the left and look down at the handle grips and front wheel and map carrier and gas tank I get one pattern of sense data. If I move my head to the right I get another slightly different pattern of sense data. The two views are different. The angles of the planes and curves of the metal are different. The sunlight strikes them differently. If there's no logical basis for substance then there's no logical basis for concluding that what's produced these two views is the same motorcycle.

Now we've a real intellectual impasse. Our reason, which is supposed to make things more intelligible, seems to be making them less intelligible, and when reason thus defeats its own purpose something has to be changed in the structure of our reason itself.

Kant comes to our rescue. He says that the fact that there's no way of immediately sensing a "motorcycle," as distinguished from the colors and shapes a motorcycle produces, is no proof at all that there's no motorcycle there. We have in our minds an a priori motorcycle which has continuity in time and space and is capable of changing appearance as one moves one's head and is therefore not contradicted by the sense data one is receiving.

Hume's motorcycle, the one that makes no sense at all, will occur if our previous hypothetical bed patient, the one who has no senses at all, is suddenly, for one second only, exposed to the sense data of a motorcycle, then deprived of his senses again. Now, I think, in his mind he would have a Hume motorcycle, which provides him with no evidence whatsoever for such concepts as causation.

But, as Kant says, we are not that person. We have in our minds a very real a priori motorcycle whose existence we have no reason to doubt, whose reality can be confirmed anytime.

This a priori motorcycle has been built up in our minds over many years from enormous amounts of sense data and it is constantly changing as new sense data come in. Some of the changes in this specific a priori motorcycle I'm riding are very quick and transitory, such as its relationship to the road. This I'm monitoring and correcting all the time as we take these curves and bends in the road. As soon as the information's of no more value I forget it because there's more coming in that must be monitored. Other changes in this a priori are slower: Disappearance of gasoline from the tank. Disappearance of rubber from the tires. Loosening of bolts and nuts. Change of gap between brake shoes and drums. Other aspects of the motorcycle change so slowly they seem permanent...the paint job, the wheel bearings, the control cables...yet these are constantly changing too. Finally, if one thinks in terms of really large amounts of time even the frame is changing slightly from the road shocks and thermal changes and forces of internal fatigue common to all metals.

It's quite a machine, this a priori motorcycle. If you stop to think about it long enough you'll see that it's the main thing. The sense data confirm it but the sense data aren't it. The motorcycle that I believe in an a priori way to be outside of myself is like the money I believe I have in the bank. If I were to go down to the bank and ask to see my money they would look at me a little peculiarly. They don't have "my money" in any little drawer that they can pull open to show me. "My money" is nothing but some east-west and north-south magnetic domains in some iron oxide resting on a roll of tape in a computer storage bin. But I'm satisfied with this because I've faith that if I need the things that money enables, the bank will provide the means, through their checking system, of getting it. Similarly, even though my sense data have never brought up anything that could be called "substance" I'm satisfied that there's a capability within the sense data of achieving the things that substance is supposed to do, and that the sense data will continue to match the a priori motorcycle of my mind. I say for the sake of convenience that I've money in the bank and say for the sake of convenience that substances compose the cycle I'm riding on. The bulk of Kant's Critique of Pure Reason is concerned with how this a priori knowledge is acquired and how it is employed.

Kant called his thesis that our a priori thoughts are independent of sense data and screen what we see a "Copernican revolution." By this he referred to Copernicus' statement that the earth moves around the sun. Nothing changed as a result of this revolution, and yet everything changed. Or, to put it in Kantian terms, the objective world producing our sense data did not change, but our a priori concept of it was turned inside out. The effect was overwhelming. It was the acceptance of the Copernican revolution that distinguishes modern man from his medieval predecessors.

What Copernicus did was take the existing a priori concept of the world, the notion that it was flat and fixed in space, and pose an alternative a priori concept of the world, that it's spherical and moves around the sun; and showed that both of the a priori concepts fitted the existing sensory data.

Kant felt he had done the same thing in metaphysics. If you presume that the a priori concepts in our heads are independent of what we see and actually screen what we see, this means that you are taking the old Aristotelian concept of scientific man as a passive observer, a "blank tablet," and truly turning this concept inside out. Kant and his millions of followers have maintained that as a result of this inversion you get a much more satisfying understanding of how we know things.

http://www.virtualschool.edu/mon/Quality...part2.html