History of Reason in Western Thought

The first group of thinkers to really recognize reason as an independent concept worthy of thoughtful consideration and development, as something more than a method of efficiently applying means to ends, were the Greeks. As Plato explains in The Republic, underlying the Greek idea of reason was the conception of form. Form is an identity of structure, a pattern of commonality, that connected diverse and changing iterations of the same essential thing. The Greek word for reason meant order or relation, and it was the Greek idea that the order and relation of things was not sensed, but apprehended through intelligence, which could see the universal trait in the particular iteration. This idea of form was broken down into four sub-ideas: form as essence, which dealt with the particular by reducing it to a kind of general, by classifying this particular structure as a type of tree; form as end, which connected objects based on their common end, by recognizing that although the sprout and the tree did not appear to have any common characteristics, they were both stages on the way to the realization of one goal; form as law, which examines what is required by the characteristics of the object, that the implication of the object being a tree is that it will burn; and form as system, which would create a unity between the many forms, allowing man to think without our sensory crutches and to see all things as connected necessarily.

The idea of form as law was really important. It held that the laws it derived were certain, or necessarily true; new, not merely analytic; independent of sense, seen with intelligence not sight; universal, with no exceptions and the same for all men; objective, existing outside of ourselves; and unchanging, providing an underlying structure for sensory changes to occur upon. The dominant conception of rational law in Western thought is based on this Greek idea of the form as law.

The idea of form as system is really interesting to me. Plato would say that in a fully rational system, there would be nothing arbitrary or isolated. That is, everything would be necessarily implied by everything else, so that all the parts would give each other support. He admits that this is a difficult level of comprehension to reach, since we are cursed, through weakness of focus, to see things piecemeal, moving step by step from premise to conclusion. But, he says, we can sometimes glimpse a better way of thinking in a piece of knowledge that we are quite familiar with. “The man who knows his subject never thinks in syllogisms.” [I find this rather compelling, because I have often been visited by startling flashes of insight after long consideration of a subject. That is, I know exactly what experience he’s talking about.] Plato thought it would be possible to see things as a whole, and to not have to move one’s attention from one part to the next because one would be seeing each thing in the light of its relation to everything else. That is, one could see the whole in the part and the parts in the whole.

Plato thought that the best and happiest life was the life of contemplation. He believed that practical reason would allow us to shape ourselves into our true forms, consistent with our true natures (ascertainable through reason). Thus, reason for him was more than a power of framing or following an argument, but was a crucial element that we needed to form an accurate idea of the ends of our life or to plan that life well.  

For the next major thinker in the history of reason, we have to fast-forward a couple thousand years, to Rene Descartes. [Strictly speaking, the idea of reason continued to develop during the intervening period, but it was wedded to the Catholic Church; Aquinas was the major rationalist in this time period, and I am a fan of his. But Descartes made reason autonomous once again.] Descartes believed that reason was a “natural light” that all normal men possessed and was our one source of clear and distinct (and therefore certain) knowledge. By distinct he meant absolute knowledge, by means of which we can grasp what things are in themselves with no distorting conditions. To get at this knowledge, he believed that we had to apply the method of mathematics to all knowledge: first, deal only with “simple natures,” abstractions of such simplicity that there was no ambiguity; second, deduce their relations logically, remaining unsatisfied with any connection that is less than necessary and self-evidencing; and third, proceed from the logically prior to the logically posterior, beginning with self-evident axioms. Unfortunately, Descartes failed to apply the first two steps successfully to the real world.

Descartes believed that the difficulties of being rational were difficulties of character rather than ability, and could be overcome through discipline. Reason never errs, so it ever seems to it must be because of a non-rational influence, and the rational man must anticipate and avoid these influences if he wanted to think successfully. 

Descartes’ task was taken up after his death by the great saint of rationalism, Baruch Spinoza. He was magnificent. His main work was on ethics, but he decided that in order to know what was good for man, he had to understand man and his place in nature, and in order to do this he had to create a system of philosophy. But the only tool he used to do this was his own mind: he never appealed to authority or revelation or common consent. And he never shirked from where his conclusions led him, becoming perhaps the first philosopher to discard the existence of God and free will. As a result, his brilliant work was virtually unknown for more than a century after his death.

Spinoza believed that knowledge itself, or rational understanding of things, was the ultimate end of human action. We are animated by a drive to maintain and expand our mental beings, and our minds are always in a process of evolving towards their natural ends. Since the natural end of imperfect ideas is to ultimately become wholly perfect ideas, we are constantly striving to achieve more complete perfect understanding. For Descartes, reason was an all-or-nothing process; either you understood something or you didn't. For Spinoza, there was a scale of reason with infinite degrees of success. There were several levels of advancement that our thought moved through, although all were means of grasping connections. The first level was contingent connections, which might have been otherwise. Here we are not truly thinking, but following lines of association, loosely connecting sense-data and concepts. The second level picks out the threads of necessity running between different things and connecting unanalyzed wholes. In other words, this level was an understanding of relationships between phenomenon, cause and effect. Spinoza believed that when he grasped a causal law, he was seeing a connection that was necessary and therefore intelligible. This second level is where Descartes would have stopped, but Spinoza believed that there was one higher level, which would be an understanding of a whole, similar to Plato’s conception of form as system. Spinoza was dissatisfied with the step-by-step progression of reasoning, and the abstraction that was necessary for logical, mathematical thinking. He believed that a higher understanding could be achieved where a whole succession of steps could be instantly grasped and everything would be seen in its own context of necessary relations. A concrete thing would be a focal point for infinite lines of necessity converging upon it from the rest of the universe. Once man achieved this knowledge, Spinoza believed, his thought would be fused with God’s own divine thought. In his view, God was the universe considered as a single system, fully comprehensive and fully comprehensible. 

Spinoza did get back around to ethics, of course. He believed that morals were a matter of intelligence. To live well is to live reasonably, and people go wrong when they misconceive their own good and the good of others, usually under the influence of emotion. This led him to the conclusion that impulsive behavior was animal and thus determined, while true freedom was found in rational thought and action. Growth in rationality, he said, is to be increasingly restrained by rational law, but this was the secret to true freedom and human happiness. 

The end of rationality, in my opinion, began with Gottfried Leibniz, although I must applaud him for his realism. For Spinoza, the world was a single whole; for Leibniz, the world was an assembly of different substances, and each was subject to its own struggle to a level of clear understanding. Leibniz believed that there were two different kinds of rational insights, “eternal truths,” true for all worlds, and “contingent necessities,” which might have been different than they are. Eternal truths were the propositions of logic and mathematics, analytic statements that he failed to justify and thus fueled the positivist criticisms of rationalism in later years. Leibniz also believed that all true statements about the real world would turn out to be necessary. That is, there were no statements that were merely empirical (except that things existed); everything was determined in the nature of things. If we really understood Caesar, with all of his features and all of his context, we would be able to see that the circumstances of his death were completely necessary and determined by his nature and the nature of the world around him. “Every true predication has its foundation in the nature of things.” 

However, whereas Spinoza believed that the main principles of the even the physical sciences were self-evident truths, Leibniz realized that they were not. Nature seemed to governed by laws that render its course inevitable, but it would be unreasonable to argue that these laws were themselves inevitable, in the sense that they couldn’t have been otherwise. Unfortunately, since these principles were not self-evident, Leibniz could think of no other explanation for them but that they were divinely created and chosen. Interestingly, while he believed that God had chosen the causal laws that governed the world, he also believed that God himself was bound to what logically followed from them, since even He could not do what was logically impossible. Once these laws are in place, the course of all things is logically necessary.

Next comes Immanuel Kant, who was quite a radical rationalist, and yet somehow is most closely associated with the modern sense of rationalism. Kant believed that reason could give necessary and universal knowledge, but also acknowledged that sense data could only ever yield probability, not certainty. Therefore, our understanding of causal laws must be a priori. More radically, we supply the causal laws. In other words, nature adjusts itself to our reason. Kant held that our reason was an ordering faculty that imposed its own structure and design on the sense data it was given, and therefore our conception of the world was a product of our mind. However, we could not control this process, and we could not understand it because our minds were not up to the task. That is, our minds were incapable of understanding the world as it really is, since all we could perceive was a world created by our minds. 

By reason, Kant meant “the faculty which supplies the principles of a priori knowledge.” He held that there were three level of a priori knowledge. The lowest level he called “pure intuition,” and it gave us the categories of space and time. These are not sense data, but orders in which sense data is arranged. The second level was called “understanding,” which operated through concepts and judgments. This is the ability to see how something is embedded in a series of necessary relations. Kant believed that there were four categories that could be derived a priori about things: quantity (everything exists in a whole-part relation with something else), quality (every feature will be present to some definite degree), relation (every event will have some cause and some effect), and modality (conclusions that are not necessary or possible (both a priori), but merely actual [this is the weakest category; I think Kant just got carried away]). The highest level was composed of the ideals which serve to regulate our attempts to order our knowledge. Kant believed that our experience of the world could be broken down into outward nature and inward feelings. Reason would deal with these spheres as distinct disciplines, but then, through rational theology, the fields would have to be reunited to show how the inner life existed in relation to the rest of the rational order. In a disappointing argument, Kant said that achieving full development of our rational faculties could not be achieved in a single lifetime, therefore there must be an afterlife in which we could continue to make progress. If this development is to be realized, it must be through a power that governed both nature and human nature. Thus, Kant “proved” the existence of God. Interestingly, Kant provided a strong refutation of his own theological theory in earlier versions of his Critique. 

Hegel conceived of reason as apprehension a priori, which may be synthetic, and recognized that rational insight is of more than one type. Indeed, Hegel distinguished about 80 categories of a priori thought (Kant only identified [a probably ambitious] 17). Hegel further recognized that these forms of knowledge existed on different levels and must be arranged hierarchically. However, Hegel did not believe that the categories could be broken up into distinct categories; for him, everything was a matter of degree. He replaced Kant’s three levels with a ladder with ascending orders from abstraction to concreteness. Hegel regarded necessity, truth, and reality themselves as matters of degree. The necessity became firmer, and one’s understanding more complete, the further one moved up the ladder and approximated the comprehensive vision at the top. We ascend this ladder through the dialectic, which is a zig-zag pattern of thought whereby we define concepts, thus making them more concrete, through their relation to other concepts. Thesis moves to antithesis and then culminates in a synthesis, which begins the process over again. Hegel believed that this was the necessary method because he believed that concepts changed in different contexts, and that as our scope of understanding widened, we could not assume that the isolated connections we had made earlier would hold true in the larger picture we could now see. It was better to understand things as part of each other from the first, rather than see how each thing was connected to other things, step by step. 

The essentials of Hegel’s theory were pretty much wholly adopted by the British rational idealists like F. H. Bradley. These Brits believed that reason was an impetus towards “wholeness,” that drive in human beings to understand a thing completely and to understand its interdependence with other things. In other words, we see a fragment of reality (and this comes from Hegel), and “the opposition between the real, in the fragmentary character in which the mind possesses it, and the true reality felt within the mind, is the moving cause of that unrest which sets up the dialectical process.” Reason is our drive to complete the picture. The function of reason as it works in each of us is to construct the rational whole. Integrated knowledge demanded consistency, both in itself and through interdependence with other facts, so that every fact was connected necessarily with others and ultimately with all other facts. Only once we reached this comprehensive consistency would reason be satisfied. 

Empiricism developed alongside this process of developing rationalism, though it started later, and at the turn of the century rationalism fell from grace as the preeminent theory of knowledge in the philosophical and scientific communities [for a number of reasons, which we can discuss if you’d like]. In recent decades it has made a comeback, since other philosophies have been found to be intellectually wanting in the areas of the social sciences, even as positivism continues to be the official creed of the universities and postmodernism continues to eat away at anything resembling a rational order [or common sense].