Do We Know Anything For Sure?

Rene Descartes

There are many reasons we might want to philosophize—to become better people, gain self-knowledge, understand the history of thought, etc. But I was drawn to philosophy because I wanted to know, as far as is possible, what was true. This sentiment echoes the first sentence of the first book we read in my very first college philosophy class, way back in 1973. They are the opening lines of Descartes’ Meditations on First Philosophy:

It is now some years since I detected how many were the false beliefs that I had from my earliest youth admitted as true, and how doubtful was everything I had since constructed on this basis; and from that time I was convinced that I must once for all seriously undertake to rid myself of all the opinions which I had formerly accepted, and commence to build anew from the foundation, if I wanted to establish any firm and permanent structure in the sciences.

Later I read Descartes’ Discourse on Method where he states the origins of his doubts:

I was nourished by study from my earliest childhood; and since I was convinced that this was the means to acquire a clear and certain knowledge of all that is useful in life, I had an extreme desire to learn. But as soon as I had finished a course of studies which usually culminates in one being accepted as one of the learned, I changed my opinion completely; for I found myself troubled by so many doubts and errors that the only profit I had gained in seeking to educate myself was to discover more and more clearly the extent of my ignorance.

As many of my readers know, Descartes begins with skepticism but doesn’t end there. In fact, he’s trying to do the opposite—rid himself of his false beliefs so that he can replace them with true ones based on the firm foundation of clear and distinct ideas. He concludes that “I think, therefore I am” is that foundation. And this presumably indubitable proposition leads to the discovery of other clear and distinct ideas for Descartes—most notably the existence of the external world and God.

Then as a graduate student, I encountered  Edmund Husserl‘s Cartesian Meditations: An Introduction to Phenomenology.[image error] In it, Husserl developed what he called presuppositionless philosophy—the idea of philosophy without any presuppositions. He criticized Descartes for beginning with what he saw as unjustified presuppositions about the cogito. How did Descartes know there was an “I” doing the thinking? Instead, Husserl believed he could place philosophy on firm foundations by examining subjective consciousness.

Yet a problem bedevils those who seek foundations of knowledge. On what foundation does that foundation rest? And, if we ask this question indefinitely, we find ourselves in an infinite regress. Aristotle avoided this regress by appealing to intuitive truths, basic laws of logic on which all knowledge is based—the law of identity, the law of the excluded middles, the law of non-contradiction. Another approach is that of Jean Piaget who argued for “the circle of the sciences.” The idea that one science reduces to another in the following order: psychology -> biology -> chemistry -> physics -> mathematics -> logic and then back to psychology, thus forming a circle. (For a detailed discussion see my Piaget’s Conception of Evolution[image error].)

A different approach rejects foundationalism altogether. Consider the following quote from the Austrian-born philosopher Otto Neurath,

“We are like sailors who on the open sea must reconstruct their ship but are never able to start afresh from the bottom. Where a beam is taken away a new one must at once be put there, and for this the rest of the ship is used as support. In this way, by using the old beams and driftwood, the ship can be shaped entirely anew, but only by gradual reconstruction.”1

In this vision of philosophizing we always necessarily begin in the middle. We can’t escape our situation or get outside of ourselves to construct some foundation. According to Neurath, contra to Descartes and Husserl,  we can’t raze all that came before and begin anew but philosophical inquiry can improve our pre-philosophical views.

I think this is about right. While I desperately wanted firm foundations for my philosophical beliefs when I was a teenager, I long ago gave up that dream. Even my intellectual hero Bertrand Russell came to a similar conclusion. In  Portraits from Memory and Other Essays, he wrote of his reaction to Gödel’s ‘Theorems of Undecidability’,

I wanted certainty in the kind of way in which people want religious faith. I thought that certainty is more likely to be found in mathematics than elsewhere. But I discovered that many mathematical demonstrations, which my teachers wanted me to accept, were full of fallacies … I was continually reminded of the fable about the elephant and the tortoise. Having constructed an elephant upon which the mathematical world could rest, I found the elephant tottering, and proceeded to construct a tortoise to keep the elephant from falling. But the tortoise was no more secure than the elephant, and after some twenty years of arduous toil, I came to the conclusion that there was nothing more that I could do in the way of making mathematical knowledge indubitable.

Life is full of ambiguity, and we either tolerate it, ignore it, or escape into a fanatical ideology. We can never be absolutely certain of anything; we know of no absolute foundation on which to build knowledge. In the end, I’m a fallibilist, any idea I have might be wrong.

Still, we needn’t accept epistemological relativism either because … some ideas are much more likely to be true than others.

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Otto Neurath (1921), “Spengler’s Description of the World,” as cited in Nancy Cartwright et al. Otto Neurath: Philosophy Between Science and Politics, Cambridge University Press, 28 Apr. 2008 p. 191