[Partly edited 9/23/2011]



I made the generalization last time that Bacon, Descartes, Pascal did an excellent job helping provide order and assurance for the people of the 17th century.  Certainly Bacon's method of pursuing truth, the inductive (or scientific) method is a good one--in areas for which it is applicable.  Bacon's method helped lead to the scientific revolution and put science on a much more stable footing than it had been before.  But Bacon's method doesn't work for everything--in fact for many of the things we care most about, it is no good at all.  It is not surprising, then, that other 17th century thinkers looked for other means of obtaining certainty.  One such, Rene Descartes.

DESCARTES (Background)

Descartes (1596-1650)  was a French mathematician and philosopher (1596-1650) and one of most brilliant men who ever lived.  He was an outstanding mathematicians--perhaps the best in the world at the time. He invented analytic geometry, and we still talk of "Cartesian" coordinates when we do problems in analytic geometry today.  Descartes prepared the way for Newton's discovery of calculus later in the 17th century. Descartes was also one of leading figures in science, as I'll explain later.  But in some ways, Descartes' most important contribution was in field of philosphy. He wrote two particularly important philosophical essay, the Discourse on Method and Meditations on First Philosophy.  In these books Descartes makes clear what he considers to be the best way of arriving at certainty.

Not from authority.  Descartes had gone to a very good school and he enjoyed his studies.  But he was dissatisfied with what he had studied in school, having special problems with the fact that there were so many conflicting "authorities" in many, many fields.

Not from experience.  Much travel/many adventures doesn't make you more certain of the truth.  The more you see, at least in some areas, the less sure you are of what's really true.

So where do you find certainty?  By employing the methods of mathematics: essentially, pure reason--what we call the deductive method.


Descartes lists the basic steps of his method:

1.  Accept nothing that can be doubted (start with only a few basic axioms that cannot possibly be doubted)
2.  Break a problem into parts
3.  Proceed in an orderly way from simple to complex
4.  Go back over proof to make sure nothing is left out (make your proof rigorous)


 There are some great advantages to this method:

1.  There should be a great deal of certainty about one's answer
2.  Anyone should be able to follow proof and get the same answer

Unfortunately, there are some disadvantages as well:

1.  A Small error can lead to major problems.  Consider the following "proof":

 x=y, w=z, a=1, b=2 (Given)
 x=y (Given)

 Where is the mistake?
Signing up for this class in the first place, perhaps!  But notice the problem.  There is hidden away in the above proof a "divide by zero error," and error that is very hard to catch. If one is attempting to follow Descartes method, one has to be very, very careful not to stumble over the equivelent of a "divide by zero" error.  One has to look at every step of the proof carefully: skimming won't work!

2.  Following Descartes' method may mean taking an enormous amount of time to prove anything worthwhile

 In your high school geometry classes you almost certainly found yourself taking a great deal of time to "prove" things that seemed to you obvious at the outset.  To prove anything at all complicated wasn't quick at all.  Descartes knows that this is a potential problem, and so he adopts some provisional rules.  How do we conduct ourselves while we are searchng for certainty but haven't necessarily found it yet?  Here are the rules:


1.  Follow the customs of your country.  Just because you are uncertain the laws and customs of your country are right, that's no excuse for violating them.  The wise man gives law and custom the benefit of the doubt. 

2.  Be resolute.  There are many practical questions that have to be decided on best evidence, not certainty.  When would you choose a major if you first had to be absolutely sure that that was the best major for you?  When would you marry if you first had to be absolutely sure that this was the best husband or wife for you?  There's no point in being an irresolute Hamlet type. 

3.  Resolve to change yourself rather than fortune.  In philosophical matters, what the wise man is looking for is ways to change himself, not the world.

4.  Choose best occupation.  Descartes realizes that his method is only useful to those who have the leisure for plenty of thought about important issues: professional philosophers, perhaps.  If one plans to follow the method he advocates, find a job that gives one the time to do so.

Having established these provisional rules, Descartes now suggests the basic path one might take in pursuit of ultimate certainty.  One might think that Descartes, a great mathematician and scientist, would begin by investigating the physical world.  But, for reasons that should become apparent, he thought it necessary to start with the investiation of certain metaphysical questions, questions with issues beyond (or more fundamental than) the physical world.

1.   The first step of the method is to doubt all that can be doubted?  And what's that?  Everything!  The things I think I see in the physical world might not be real at all.   I might be crazy!  (No might about it, say some of you, perhaps).  In any case, Descartes says we should start with a completely blank slate: take nothing for granted at all.

2.  Now can we find a good starting point, any one thing can't be doubted?  Yes, says Descartes. Here's one thing I know: I am thinking.  But in order to think, I must exist. Therefore, since I know that I am thinking, I know I exist.  The famous phrase from Descartes: Cogito Ergo Sum: I think therefore I am.  You will see variations on this line all over the place, e.g., jokes.  Descartes walks into a bar.  The bartendedr asks if he wants a drink.  Descartes says, "I think not."  He disappears.  And then there is this slogan one NSU woman wore on her sweatshirt: I think, therefore I am....single.  My favorite version of this is from a family conversation some years back.  When my youngest daughter, Laurie, was four, her older brother, RJ would constantly tease her.  For a while, one of his favorite "tease" lines was, "You don't exist."  Finally, Laurie's older sister Becky gave her this advice: the next time RJ tells you you don't exist, quote Descartes: I think, therefore I am.

Well, Laurie tried it.  "You don't exist," said RJ.  And Laurie responded, "I think I'm four: I am!"  Yes--the beginnings of a great philosophy....

3.  In any case, the first thing I can be certain of, says Descartes, is that I think.  Next, I can be certain I exist.  And I know also that I have certain ideas.  Ideas of things like  unicorns, hydrogen, square circles, dragons, shoes, God, interesting history teachers, oceans, water, myself.  I don't yet know if any of these ideas represent things that really exist, but do know I have ideas of each of these things.

4.  Can I go any farther?  Yes, says Descartes.  Many of my ideas seem to stand in a special relationships to each other.  Some ideas are contingent on others, while some are not.  Take hydrogen, water, and oceans or shoes and shoemaker.  If one knows oceans exist, it implies also existence of water, hydrogen, things on which ocean is contigent--though it's not the other way around.  One might very well have water without there being an ocean. 

5.  Now consider the relationship betwen two important ideas, my idea of God and my idea of myself. My idea of God is that God is a perfect, all-powerful creator who has existed from all eternity.  My idea of myself is of an imperfect, finite creature who hasn't been around all that long.  Now is one of these ideas contingent on the other?  Could there be a God without an Art Marmorstein?  Of course there could. God's existence is obviously not contingent on the existence of a finite being like myself.  But could there be an Art Marmorstein without God? No--it doesn't seem possible for a being like myself to come into existence without the creative act of a trancendent being.  My existence, then, is contingent on God's existence. 

But what do we know about me (we know your boring and that you tell stupid jokes). Well, ok.  But what I know philosophicall is that I exist (cogito ergo sum).  And if I exist, and my existence is contingent on God's existence, then God must also exist!  We have proved the existence of God!

6.  Many have some difficulty with this, and Descartes explains why.  You are simply too used to trusting your senses.  But, can you really put such faith in your senses?  No--if there is no God, the world might be the creation of of malevolent being who hates you (sort of like being in Mark Twain's Mysterious Stranger--an absolutely horrifying book).  All these wonderful things around you are just illusions to make torment worse when you find them all taken away.  Descartes argues that, unless one knows that there is in charge of things an all-powerful God who does not lie, we can never be sure that what our senses tell us is real.  But, if one does know that there is a truthful God in charge of all things, one can trust one senses: God would not deceive us.  

Does this mean we just believe things are whatever they appear to us to be?  No.  While God doesn't deceive us, we are limited and imperfect.  As a result, we must do the kind of thing Bacon recommends, go out and investigate world around us systematically, using reason to help us come up with best understanding of data we collect.  Interestingly enough, Descartes was actually more successful than Bacon in exploration of physical world,


Descartes' uses his method especially well in discussing two particularly important controversies.  He comes up with good proofs for both 1) Harvey's ideas on the circulation of blood  and 2) Copernicus' ideas on astronomy.

In addition, using this method allowed Descartes to come up with an entirely new theory of physics, which, if not as accurate as that of Newton later in the 17th century, still was much better than any other that existed at the time and served as the inspiration for two generations of French scientists.

All this is quite impressive.  If one has the patience and follows Descartes step by step, you end up with certainty about existence of God, the soul, the general reliability of the senses--and with a method of investigating the natural world that seems to provide some solid results.  Still, there's one major problem--one weak link in chain of proof.

Descartes' jump from his own existence to God's doesn't seem completely justified.  Is it really so that I couldn't exist unless there was a God, and that my existence demonstrates that God must exist?

This is, of course, is one of the central question in the Meditations--and Descartes does his best to show that the existence of God really cannot be doubted.  He does this in a number of ways, modifiying some of the traditional arguments for the existence of God and, in each case, improving and expanding them.  He offers the following:

1.  A  modified first cause argument.  Philosophers from Aristotle to Aquinas and beyond had argued that all things we see have causes, and all  those causes have other causes.  The whole thing must start somewhere with an uncaused first cause.  The uncaused first cause is God).  Usually, the first cause argument is based on physical phenomena, and Descartes has this partially in mind.  But he also applies the first cause argument to world of ideas, suggesting that the idea of God must come from God.  All ideas have causes: they spring from other ideas that spring from other ideas. There must be a beginning to the generation of ideas--and that beginning is God.  Indeed, there must be a beginning to everything: and that beginning must be that infinite source of being we call God.

2.  A modified argument from design.  The argument from design suggests that the world is an orderly place.  It follow from this that there must have been a force to set it in order.  Sometimes, this is called the watchmaker argument. Something as complex as a watch implies an intelligent being behind it, and we can infer that there must be a watchmaker even without other evidence.  Something as complex as world, must have a being much more intelligent than even the finest watchmaker behind it--and implies that there must be a God. 

Descartes expands and improves this into what we might call a sustainer argument.  Both the argument from design and the first cause arguments tend to leave God very distant.  God starts everything, then steps out of picture. This is not the way Descartes looks at it.  Descartes argues that God not only started all, but continues to sustain it, insisting that without God, without a force sustaining the order of creation, everything would immediately fall apart and cease to exist. Descartes' argument is essentially that things depend, not merely on antecedent causes, but on certain conditions right now. All things we depend on right now, depend on other things--and ultimately on God.

3.  A modified ontological argument.  An ontological argument is one that says that God, by definition, must exist.  It begins with a definition of God, e.g., St. Anselm's definition that God is the greatest being you can think of.  Descartes expands on this in an interesting way.  When I turn inward and look at my own existence, he says, I get a sense that I am not everything, that I am merely a part, and a small part of something much greater, part of something that, ultimately, is infinitely greater.  All have sense of this in terms of material world--and it's obviously true.  But Descartes is talking about something even larger, than the physical universe, what he calls "infinite potentiality"--all that might be thought, all that might be said, all that might be done.  This, he says, is God--and, if this is how you define God, well--obviously he exists.


But is all this helpful?  For Descartes and some others, definitely yes--but there are a couple of problems, some things that make Descartes less helpful than he might be in providing assurance that what one believes is true.

 1.  Descartes proof is rather complex.  It's not easy to follow, and even if you do follow, there seem to be some loopholes Descartes hasn't quite closed.  Any proof of the type Descartes attempt must be flawless.  If there is any error here, the whole thing collapses, and one suspects that there just might be a division by zero error here somewhere.

 2.  The other problem is, that, even if Descartes's proof is valid, it doesn't prove very much.  God exists?  Fine.  I've always suspected that he did.  But what does that mean to me?  What does that mean to my life?  Descartes has not proved the existence of the God of Abraham, Isaac and Jacob.  He has not proved the existence of a God who loves me and has a wonderful plan for my life.  What he's proved is the existence of a philosopher's God--a concept, the concept of infinite potentiality.  What he offers us is, in many ways, a typical mathematicians proof, and, for those who want something more--assurance about a God who cares about them--the man we talk about next has, perhaps, more to offer than Descartes.  Next up: Blaise Pascal.