Immanuel Kant (1724-1804)

Kant was born in Königsberg, East Prussia (modern Kaliningrad.) His father was a master harness maker. He and his family were poor and were pietists, a reform movement within the Lutheran church that believed in hard work, duty, and prayer. Despite his family’s poverty, Kant was able to attend a pietist school and later the University of Königsberg. After, he tutored and lectured for many years, turning down offers elsewhere before accepting a professorship at Königsberg at the age of 46. Kant taught in a wide variety of subjects before specializing in philosophy and was the first to propose the nebular hypothesis for the formation of the solar system. He became a fixture in town because of the popularity of his lectures and the regularity of his schedule. He always woke early, wrote for two hours, gave his morning lectures, had lunch with friends, and then took a solitary walk. He was inspired by the writings of Rousseau and Newton and saw himself as the Copernicus of philosophy. Most divide his writings into two parts, those written before the Critique of Pure Reason and those after. That book, along with two others with similar titles, the Critique of Practical Reason, and the Critique of Pure Judgment, made him internationally famous.

The title of the Critique of Pure Reason was directed at Leibniz’s rationalist philosophy, but it also attacked Hume’s skeptical version of empirical philosophy. Against Leibniz, Kant argued that reason alone could not yield a cogent rationalist philosophy, nor did he believe that Leibniz’s monads were required to understand the physical world. Instead, Kant believed that the ordinary objects of experience existed, occupied space, and endured through time themselves as they were. Against Hume, he argued that empirical observations alone could not account for the complexities of human behavior. Kant believed that the human mind came provided with a priori innate organizing principles that enabled it to make sense of experience. He proposed what he termed a transcendental idealism or an a priori synthetic approach to knowledge about the physical world. For Kant, a synthetic approach meant that the a priori categories of mind combined with sensory observations to reveal the truths of the physical world. That approach also set limits as to what topics could not be addressed by philosophy. The categories were analytic, meaning they were already present in the mind and did not depend upon experience for their existence. Kant proposed 12 categories: unity, plurality, and totality for concept of quantity; reality, negation, and limitation, for the concept of quality; inherence and subsistence, cause and effect, and community for the concept of relation; and possibility-impossibility, existence-nonexistence, and necessity and contingency for the concept of modality. He derived all of them by deductively working backwards until he could go no further. The categories, in other words, represented the very bottom level of conceptual organization. In addition to the categories, Kant proposed two innate intuitions: space and time. Thus, against the empiricists, Kant argued that humans came into the world already knowing about space and time along with the 12 categories; they did not have to learn them through experience. He held that scientific facts resulted from the combination of observations of the physical world made by a prepared and already organized mind. Kant’s philosophy suggested that a unified science was possible with common principles, such as the law of conservation, applicable to all branches of science. Kant’s logic dictated that some things: God, the immortality of the soul, and freedom were impossible to know. Those kinds of things were outside of experience and thus could not approached by his method. However, knowing that they were unapproachable to speculative (e.g., scientific) philosophy was important. By separating such topics out Kant solved the “Crisis of the Enlightenment.” That crisis had long been brewing and it revolved around the relationship between philosophy and theology that had become more and more acute since the Middle Ages. Descartes, Spinoza, Malebranche, and Leibniz had each felt compelled to include a place for God in their philosophical systems. Locke and Berkeley too, each had a role for God within their philosophies as well. Hume, eventually, had separated God from his philosophy but in a manner intolerable to most of his contemporaries. Kant’s synthetic approach removed the necessity for a place for God in philosophy but kept open a place for worship, reverence, and belief in God. That place, however, was outside of speculative philosophy.

Kant next turned his attention to practical reason. There, he wished to discover similar synthetic a priori principles of action based upon reason and not upon passions. Reason, not passions, could provide the marching orders to autonomous and free human agents who could decide whether or not to obey those orders. Kant’s aim was to make moral decisions independent of the empirical world. In other words, he wanted to provide a basis for moral behavior that was free of the relativism of hedonistic impulses. Reason, he thought, could provide hypothetical or categorical imperatives. Hypothetical imperatives used the word “if” and were of the form: “If you don’t want to get wet stay inside while it is raining.” Categorical imperatives, on the other hand, had the word “ought” in them. “You ought always keep your promises” would be an example. In addition, Kant posited a top-level categorical imperative that applied to all rational humans, similar to the “Golden Rule” (e.g., “Do unto others as you would have them do unto you.”). Categorical imperatives did not require empirical validation. Instead, they validated themselves logically whenever an action led to moral behavior. For example, promise keeping was a categorical imperative because if everyone broke their promises, denying that promises were a universal good, then that would lead to a logical absurdity, the end of promises themselves. Notice that Kant did not believe that all people kept their promises. Instead, he believed that all people ought to keep their promises. Furthermore, he was convinced that he had proven the existence of categorical imperatives without having to cross into the empirical world. He had shown that moral behavior was innate and universal. But, people still had to choose to act morally; they had free will. In the Critique of Practical Reason Kant argued that humans were free only when they were not subject to outside forces. Because he believed that everything in the physical world had a cause, he could not locate human freedom there. If he did, then no act made by a human could be truly free. One could always find a cause. Thus, he to make freedom an idea located outside of the empirical world. Once he placed freedom in that ideal world, humans could contemplate actions and decide, ahead of time, whether or not to carry them out.

Although Kant’s philosophy is not always logically consistent, it nevertheless represents a major breakthrough in the history of philosophy. Singlehandedly, he showed a necessary connection between rationalism and empiricism, peacefully separated philosophy from theology, and provided an innate role for reason in the making of moral decisions. By arguing against Leibniz’s version of rationalism Kant showed that pure reason led to illusory and false conclusions. By adding the categories of mind to the sensory observations of the empiricists he created a wider arena for the development of modern science. The 19th century also saw the rise of other philosophies with psychological import. The Romantic Movement arose from Rationalism and dominated the German-speaking world. Sensationalism and Utilitarianism emerged from Empiricism and each was at home on both sides of the English Channel.

Kant influenced psychology’s future as well. Topics such as consciousness and cognition derive directly from Kant. He was also ultimately correct about the futility of introspective methods in psychology, although psychologists would only learn that the hard way, through the failure of those methods (see chapter 10). Kant did not foresee the eventual development of a scientific psychology, however. It is tempting to speculate that no philosopher of his era could have predicted psychology’s future either given 21st century psychology’s eclectic background. It is only when all of psychology’s parent disciplines are examined that its own emergence as a science seems inevitable. In chapter 7 the synergy between modern philosophy and biology will be examined. The 19th century scientific breakthroughs in biology provided impetus for experimental and theoretical science. They also led directly to one of psychology’s oldest fields: psychophysics.

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