NO DOUBT

Caption: This man is no Cartesian; he didn't think, therefore he swam.

El Cabrero has been musing this week on the nature of scientific knowledge. I haven't got very far, but it is Friday, which should count for something.

There are two influential thinkers of the early modern period who are often credited with getting the ball rolling. One, Francis Bacon, was the subject of yesterday's post. Today's is about his polar opposite, Rene Descartes (1596-1650), who gave us both analytical geometry (to which I have never been formally introduced) and, indirectly, the "Matrix" movies.

As I mentioned yesterday, Bacon believed that empirical induction was the way science needed to proceed. For him, experience was the key. He was mistrustful of deductive reasoning and math was way down on his list.

For Descartes, experience and observation were problems, not solutions, since we could easily be deceived by our senses. He recommended a deductive, mathematical approach to the development of the sciences, with experiment and observation way down on his list.

However, most people remember Descartes for his famous thought experiment of systematically doubting everything in order to arrive at some kind of certainty:

I had long before remarked that, in relation to practice, it is sometimes necessary to adopt, as if above doubt, opinions which we discern to be highly uncertain, as has been already said; but as I then desired to give my attention solely to the search after truth, I thought that a procedure exactly the opposite was called for, and that I ought to reject as absolutely false all opinions in regard to which I could suppose the least ground for doubt, in order to ascertain whether after that there remained aught in my belief that was wholly indubitable.

This included doubting the senses and even the existence of the external world:

Accordingly, seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us; and because some men err in reasoning, and fall into paralogisms, even on the simplest matters of geometry, I, convinced that I was as open to error as any other, rejected as false all the reasonings I had hitherto taken for demonstrations; and finally, when I considered that the very same thoughts (presentations) which we experience when awake may also be experienced when we are asleep, while there is at that time not one of them true, I supposed that all the objects (presentations) that had ever entered into my mind when awake, had in them no more truth than the illusions of my dreams.

Then he hit what he thought was bedrock:

But immediately upon this I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be somewhat; and as I observed that this truth, I think, therefore I am (COGITO ERGO SUM), was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the sceptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search.

All this is from his Discourse on the Method of Rightly Conducting the Reason and Seeking for Truth in the Sciences, although he develops these ideas again in a different form in the Meditations on First Philosophy.

It's there that at least one of the inspiration for the Matrix movies came from. In the course of his doubt (from which he extricates himself with a not altogether convincing ontological "proof" of the existence of God), he imagines that

some malignant demon, who is at once exceedingly potent and deceitful, has employed all his artifice to deceive me; I will suppose that the sky, the air, the earth, colors, figures, sounds, and all external things, are nothing better than the illusions of dreams, by means of which this being has laid snares for my credulity; I will consider myself as without hands, eyes, flesh, blood, or any of the senses, and as falsely believing that I am possessed of these; I will continue resolutely fixed in this belief, and if indeed by this means it be not in my power to arrive at the knowledge of truth, I shall at least do what is in my power, viz, suspend my judgment ], and guard with settled purpose against giving my assent to what is false, and being imposed upon by this deceiver, whatever be his power and artifice.

In modern times, this is known as the Brains in a Vat problem (as in how do we REALLY know that we ain't?), which is one of the main ideas behind the Matrix movies.

All I know is my legs would be a lot less sore if you could just download martial arts like they do in those movies...

WHEN SQUIDS ATTACK...Jumbo squid around 7 feet long and weighing 100 pounds are becoming more common off the coast of California. And they're mean.

STICKER SHOCK. For the latest on the costs of the Iraq war (what we've paid for so far anyway), click here.

GOAT ROPE ADVISORY LEVEL: ELEVATED