Robert Pirsig - Zen and the Art of Motorcycle Maintenance

Hume would have answered that the eighteen-year-old had no thoughts whatsoever, and in giving this answer would have defined himself as an empiricist, one who believes all knowledge is derived exclusively from the senses. The scientific method of experimentation is carefully controlled empiricism. Common sense today is empiricism, since an overwhelming majority would agree with Hume, even though in other cultures and other times a majority might have differed.

The first problem of empiricism, if empiricism is believed, concerns the nature of “substance.” If all our knowledge comes from sensory data, what exactly is this substance which is supposed to give off the sensory data itself? If you try to imagine what this substance is, apart from what is sensed, you’ll find yourself thinking about nothing whatsoever.

Since all knowledge comes from sensory impressions and since there’s no sensory impression of substance itself, it follows logically that there is no knowledge of substance. It’s just something we imagine. It’s entirely within our own minds. The idea that there’s something out there giving off the properties we perceive is just another of those common-sense notions similar to the common-sense notion children have that the earth is flat and parallel lines never meet.

Secondly, if one starts with the premise that all our knowledge comes to us through our senses, one must ask, From what sense data is our knowledge of causation received? In other words, what is the scientific empirical basis of causation itself?

Hume’s answer is “None.” There’s no evidence for causation in our sensations. Like substance, it’s just something we imagine when one thing repeatedly follows another. It has no real existence in the world we observe. If one accepts the premise that all knowledge comes to us through our senses, Hume says, then one must logically conclude that both “Nature” and “Nature’s laws” are creations of our own imagination.

This idea that the entire world is within one’s own mind could be dismissed as absurd if Hume had just thrown it out for speculation. But he was making it an airtight case.

To throw out Hume’s conclusions was necessary, but unfortunately he had arrived at them in such a way that it was seemingly impossible to throw them out without abandoning empirical reason itself and retiring into some medieval predecessor of empirical reason. This Kant would not do. Thus it was Hume, Kant said, who “aroused me from my dogmatic slumbers” and caused him to write what is now regarded as one of the greatest philosophical treatises ever written, the Critique of Pure Reason, often the subject of an entire University course.

Kant is trying to save scientific empiricism from the consequences of its own self-devouring logic. He starts out at first along the path that Hume has set before him. “That all our knowledge begins with experience there can be no doubt”, he says, but he soon departs from the path by denying that all components of knowledge come from the senses at the moment the sense data are received. “But though all knowledge begins with experience it doesn’t follow that it arises out of experience.”

This seems, at first, as though he is picking nits, but he isn’t. As a result of this difference, Kant skirts right around the abyss of solipsism that Hume’s path leads to and proceeds on an entirely new and different path of his own.

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.