In Part 2 of his book Discourse on Method, he elaborated both his traditional and modern attitude towards education. He explained that since mathematics has achieved the certainty for which human thinkers seek, the traditional persons should rightly turn to mathematical reasoning as a model for progress in human knowledge. Expressing perfect confidence in the capacity of human reason to achieve knowledge, Descartes proposed an intellectual process that suggested the architectural destruction and rebuilding of an entire town. In Part 2, he writes:
It is true, however, that it is not customary to pull down all the houses of a town with the single design of rebuilding them differently, and thereby rendering the streets more handsome; but it often happens that a private individual takes down his own with the view of erecting it anew, and that people are even sometimes constrained to this when their houses are in danger of falling from age, or when the foundations are insecure.
What is true of buildings and constitutions is also true for knowledge. The fact that the existing sciences have often grown up gradually with no uniform plan explains this as a key role of processing the "unlearning" of what we have previously learned. Descartes used that as an example to explain that in order to be absolutely sure that we accept only what is genuinely certain, we must first deliberately renounce all of the firmly held but questionable traditional beliefs we have previously acquired by experience and education. However, he later warns about the consequences of the reconstruction, such that:
For although I recognized various difficulties in this undertaking, these were not, however, without remedy, nor once to be compared with such as attend the slightest reformation in public affairs. Large bodies, if once overthrown, are with great difficulty set up again, or even kept erect when once seriously shaken, and the fall of such is always disastrous (Discourse, Part 2).
Furthermore, he explained that if there are any imperfections in the constitutions of states, tradition has materially leveled their problems and will manage to steer clear of the defects. Thus, in this part, Descartes denies that his plan to undertake the reform of knowledge has a revolutionary design. He believed that it would be unwise to undertake the reform of a state or education by undertaking it from the ground up. However, regarding his own opinions and beliefs, it would be preferable "to get rid of them, all at one go, in order to replace them afterward with better ones."
Hence, Descartes finds himself caught in the middle between two types of people. There are those on whom "God has bestowed more of his favors" and will no doubt see his plans for self-improvement as too cautious. Then, there are others who are content to follow existing opinion and practice as the only reliable guide. Descartes advised that he would have included himself in this second class, if he had not come upon a discovery that there is no opinion or custom so strange that it has not been held or practiced by someone somewhere. He mentions that his travels merely confirmed to him that custom is variable and that we hold the opinions we do purely as a matter of chance.
2. The Middle Ages was characterized by two intellectual crises that profoundly affected Western civilization. First, the decline of the traditional Aristotelian thought that eventually questioned the methods and