A Wanderer's Guide

When the Thirty Years War started in 1618, Rene Descartes was 22 years old. This war spanned most of the rest of his life. Instead of becoming a lawyer like his family wanted, he joined the army. So by the time he wrote his the book that changed the course of western philosophy Discourse (1637) (the full name is Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences), he had spend the past 19 years of his adult life in the midst on an ongoing war. Descartes was also a great mathematician. I mention these parts of his biography because, to me, they help make sense of his project. He sought order and certainty in an uncertain world. He attempted to give the whole world the kind of order and certainty that mathematics can provide. In this quest he systematically doubted everything he could until all he was left with was his doubt. Doubting his senses was easy. We've all been fooled at one time or another by our senses. But there was one thing he could not doubt, that was his doubt.

We're kind of stuck. Stuck with our own brains, bodies, and other brains and bodies. We have a few holes in our head that allow us to experience some of the world outside, but we cannot always rely on these holes to give us accurate information. Descartes was so convinced that his senses were not good guides to knowledge that he sought a sure foundation through reason and came up with "I think, therefore I am" (cogito ergo sum). Too bad reason isn't any better of a guide through this world than our senses are.

In this battle of ideas, John Locke had a bit of a different solution. He wrote that knowledge is "the perception of the connexion and agreement or disagreement and repugnancy of any of our Ideas" (An Essay Concerning Human Understanding (1689)). Instead of seeking ideas that were clear and distinct, as Descartes had done, he allows for those holes in our head to contribute to our ideas. Locke's famous analogy is to a blank piece of paper that our perceptions essentially write on. When we are born our mind is a blank slate and our experiences write on that slate. Then we can use our reason to compare our various ideas and try to decide which are agreeable to us. Repugnant ideas are to be cast aside. But in a sense, this is exactly what Descartes was trying to do. Descartes knew that he had a bunch of false ideas about the world and he was looking for a way to figure out which of those were trustworthy and which were the false ones. 

Instead of a cave, like Plato had proposed, I prefer to think of myself as wandering around in a forest. I would be happiest if that forest was Kings Canyon in California, or the Coastal Redwoods like these in Muir Woods National Monument:

There are bears and other dangers and it's easy to get lost. Our perceptions of direction and distance can be unreliable when we are hiking in the forest. But if we are prepared, and especially if we have a good guide, or guides, who can show us around, we can enjoy ourselves and discover some wonderful things about this world. 

I'm not really prepared to supply some final resolution between Descartes and Locke. The debate they were engaged in has been going on ever since the 17th century. What I do want to propose is that there are some good guides we can follow as we wander around. The scientific method has probably gotten us further than anything else through this forest of uncertainty. The scientific method relies on both our senses and our reason. Together they can help us overcome the limitations that either alone can offer.

A child sees a butterfly and starts to follow it. Fully engaged in using her senses, purposely pursuing her prey, she runs from one flower to the next, around trees and over a stream. After half an our of this she finally looses interest. She turns around only to find herself hopelessly lost. Yes, our senses alone can lead us astray. But reason alone, without actually looking to see what's out there is also of little use. As the father sits in front of his tent in the woods, he isn't going to get any closer to finding his daughter before the night comes. It takes both open eyes and a keen mind to survive in the woods. 

Sometimes our senses do deceive us, but we can analyze the situation with our reason and overcome these limitations. We can ask someone else to take a look and see what they think. We can recognize biases in our reasoning and come up with way to overcome these biases. Careful observation, detailed notes, statistical analysis, and having someone else try to replicate our data are just some of the ways we can gain a more useful understanding of the world we live in. 

Go out and go hiking somewhere. But don't go unprepared.