Why Philosophy? (2) Seeking Foundations

by John Schwenkler

This is the second in a series of posts discussing different ways of pursuing philosophical understanding.

My first post in this series explained how philosophy can aim to help us become articulate about things we already understand at a practical or intuitive level, much as drawing a map makes explicit the knowledge we have in being able to find our way around a certain place.

At the end of the post I considered several objections to this project, including that it is too conservative and uncritical to count as a philosophical endeavor. According to this objection, the project I envisioned is inadequate because of the way takes our ordinary ways of thinking for granted and isn’t concerned to replace our philosophical beliefs with better ones. At the end of this post I will explain again why I think this objection misfires, but first I want to discuss a different approach to philosophy that has an opposite orientation in these respects, and consequently takes a quite different stance on the value of “common sense.”

The opening lines to the French philosopher and mathematician René Descartes’ classic philosophical text, the Meditations on First Philosophy, capture beautifully the attractiveness of this alternative philosophical project. Descartes titled his first meditation, “Of the things which may be brought within the sphere of the doubtful,” and it begins as follows:

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.

Many people know of the famous thought experiment that Descartes develops in the subsequent pages, in which he imagines that all his thoughts and perceptions are the product of “an evil genius … [who] has employed his whole energies in deceiving me.” For Descartes, the purpose of this thought experiment was to rein in the habits of credulity that had led him in his youth to admit false things as true ones. He was instead to adopt a skeptical attitude, believing only those things whose truth he could see for himself in a “clear and distinct” way.

But Descartes was not really a philosophical skeptic, and the opening to the first meditation already reveals this. The reason why Descartes wished to get rid “of all the opinions which [he] had formerly accepted” was not to leave himself in a state of disbelief, but rather to make it possible for his beliefs to be based on a foundation of firm knowledge instead of on a mess hearsay and so-called “common sense.” Just as a building constructed on shaky ground needs to have its foundations torn out and replaced in order for it to become secure, so Descartes wished to use his skeptical hypothesis to demolish his old beliefs and then build a “firm and permanent structure” of scientific knowledge upon what he put in their place.

Another one of Descartes’ great analogies helps to make clear the difference between this philosophical vision and the one I developed in my earlier post. The second part of Descartes’ Discourse on Method argues for the greater perfection of artefacts that are produced by “a single master” rather than the joint work of many separate hands. For example:

those ancient cities which, from being at first only villages, have become, in course of time, large towns, are usually but ill laid out compared with the regularity constructed towns which a professional architect has freely planned on an open plain; so that although the several buildings of the former may often equal or surpass in beauty those of the latter, yet when one observes their indiscriminate juxtaposition, there a large one and here a small, and the consequent crookedness and irregularity of the streets, one is disposed to allege that chance rather than any human will guided by reason must have led to such an arrangement.

Descartes’ urban architect would not be satisfied with a map that shows the layout of a city as we find it, with winding roads laid out along the paths that cows once followed. Her wish is to start with a plan and build the city from there, its order and symmetry reflecting its origin in rational thought rather than chance and arbitrary custom. In the same way, the Cartesian philosopher wishes to build an orderly system of knowledge on the foundation of rational philosophical thought.


Many people’s response to this project is simply to say: wait a minute—are you really telling me that philosophy is going to give you the foundation for a firm and permanent system of knowledge? Why not start instead with something that is, you know, actually firm and permanent, such as mathematics and natural science?

But Descartes was no enemy of mathematical and scientific thinking. Indeed, the ultimate aim of his philosophical was to convince an audience of 17th-century Catholics to drop their opposition to the mechanistic worldview of modern science. He saw, however, that this opposition was driven largely by the way that people for granted the scholastic philosophy that they had been taught from their youth, and of trusting in the veridicality of sense perception rather than rational thinking. The path of Descartes’ solitary meditator was supposed to be a way of disrupting these habits, so that a proper respect for the authority of reason could take their place.

But even when the things we are taught in our youth have more to be said for them than the Aristotelianism of the late middle ages, the trouble with this objection is simply that scientific thinking is totally unable to establish its own legitimacy. For as its detractors never tire of reminding us, science is a human construction that presupposes the reliability of reason and sense perception. It would be viciously circular to appeal to science itself in order to justify our reliance on scientific thinking. Any fundamental claims about the possibility of human knowledge are going to be justified philosophically, if indeed they can be justified at all.

But the threat of circularity arises for the philosophical enterprise, too. Philosophers reach their conclusions through the exercise of human reason. Can we justify this reliance without relying on the very thing we are trying to show is reliable? In the Meditations, Descartes tried to use the security of clear and distinct perception to demonstrate the existence of an all-powerful God, whose goodness ensures that if we reason carefully, we will not go astray. But almost everyone who has examined these arguments has found them insufficient, if not outright circular. We should not be optimistic about the prospects of finding any firm foundation on which the rest of our knowledge can stand secure.


One of the great philosophical images of the 20th century is due to the Austrian-born philosopher Otto Neurath, whose essay “Anti-Spengler” offers the following in a rebuke to the quest for absolute foundations:

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.

Neurath’s vision of philosophical inquiry — always beginning in medias res, and doing our work piecemeal with whatever resources happen to be at hand — will be a disappointment to anyone who takes their bearing from the foundationalist imagery of Descartes’ Meditations. But for Neurath, the need to carry out philosophical inquiry in this way reflects the fact that our concepts themselves lack the independence that would be needed for any one part of our knowledge to serve as foundation for the rest.

Just as importantly, Neurath’s image of philosophy shows us that the decision to begin where we are, mapping out the structure of the world as we find it rather than razing all to the ground in the search of something better, does not mean that we cannot use philosophical inquiry to improve on our pre-philosophical views. Leaks in our will need to be plugged, and rotten planks replaced. We can do this work as we go, even in the absence of dry ground to build on.