Immanuel Kant

kantToday, Kant is primarily remembered as one of the most influential philosophers in the history of Western philosophy. His contributions range across metaphysics, epistemology, ethics and aesthetics. Subsequently, his work was to have a profound impact on many of the philosophical movements that were to follow. However, he is included in this section primarily because of his summation of cosmology, which could be viewed as a pinnacle of an era that will in-turn herald the start of modern science.

His Life

Kant was born in Königsberg, Prussia in 1724, which is now Kaliningrad, Russia. He received his primary education at the University of Königsberg, but due to the death of his father, he was initially forced to halt his university career and earn his living as a private tutor. However, by 1755, he had resumed his studies and obtained his doctorate and for the next 15 years teaches at the university. Kant first lectures on science and mathematics, but gradually begins to focus on philosophy and soon begins to establish a reputation as an original philosopher. Surprisingly, given his now established reputation, he was only made professor of logic and metaphysics in 1770, aged 46.

For the next 27 years, Kant continued to teach at Königsberg, while writing and publishing many of his most famous works. However, Kant's unorthodox religious teachings based on rationalism, rather than revelation, brought him into conflict with the government of Prussia. In 1792, Frederick William II, the King of Prussia, forbade him to teach or write on religious subjects. Kant obeyed this order for the next five years, until the death of the king, after which he felt released from this obligation. In 1798, the year following his retirement from the university, he published a summary of his religious views. At the age of 80, Kant died February 12, 1804, having hardly travelled outside the area in which he was born. Even so, he left behind him a perspective of the universe that few could match.

His Work

The following list provides some initial outline of the scope of Kant's work throughout his life:

Major Works Date Age
o Thoughts on the True Estimation of Living Forces   1746   22
o General Natural History and Theory of the Heavens   1755   31
o New Theory of Motion and Rest   1758   34
o Some Experimental Reflections about Optimism   1759   35
o Possible Argument for Proving the Existence of God   1763   39
o Principles of Natural Theology and Morality   1762   40
o Critique of Pure Reason   1781   57
o Idea for a Universal History   1784   60
o What is Enlightenment?   1784   60
o Foundations of the Metaphysics of Morals   1785   61
o Metaphysical Foundations of Natural Science   1786   62
o Conjectural Beginning of Human History   1786   62
o Critique of Practical Reason   1788   64
o Critique of Judgement   1790   66
o Religion Within the Limits of Reason Alone   1793   69
o The End of All Things   1794   70
o Perpetual Peace   1795   71
o The Metaphysics of Morals   1797   73
o Logic   1800   76

Critique of Pure Reason

The keystone of Kant's philosophy is contained in his `Critique of Pure Reason (1781)`, in which he examined the basis of human knowledge and outlines his own methodology. Kant separates modes of thinking into two types of proposition, i.e. analytic and synthetic.

  • An analytic proposition can best be illustrated by an example, e.g. white houses are houses. The proposition appears evident, because to state the reverse would be to make the proposition self-contradictory.


  • A synthetic proposition is one that cannot be arrived at by pure analysis, e.g. the house is white. Generally, propositions resulting from experience of the world are synthetic.

Kant also argued that these modes of thinking could also be divided into two types, i.e. posteriori and a priori. The philosophical definitions behind these concepts can be convoluted, the following summary simply attempts to capture the essence in terms of two positions already outlined, e.g. rationalism and empiricism.

  • Priori propositions have a rational validity
  • Posteriori propositions are based on empirical perception

Kant argues that our perception of experience of the world is only possible, if the mind provides a systematic structuring of experience. This structuring occurs before the normal processing of information, which differed from that described by either the Empiricists or Rationalists. Therefore, Kant believed their theories did not adequately explain the process of human judgements, because they only considered the mind's interaction with the world and did not account for the mind's own contribution to our view of the world. Kant's then introduced the notion of what he called a transcendental argument, i.e. there are objects that exist outside of one-self, which cannot be proved by either our rational or empirical perceptions, therefore to be aware of one-self existing, you must also have to envisage the existence of something else as a frame of reference. In Kant's words:

"There are objects that exist in space and time outside of me, which cannot be proven by a priori or a posteriori methods, that are a necessary condition of the possibility of being aware of one's own existence. It would not be possible to be aware of myself as existing without presupposing the existing of something permanent outside of me to distinguish myself from. I am aware of myself as existing. Therefore, there is something permanent outside of me".

In addition to these insights, Kant defined a number of a priori concepts, which he called categories. He divided the categories into a number of distinct groups:

Quantity: Quality: Relation: Modality:
unity, reality, substance-and-accident, possibility,
plurality, negation, cause-and-effect, existence,
totality; imitation; reciprocity; necessity.

While we may use these categories to make judgements about our experiences, we cannot apply these categories to abstract ideas, such as freedom and existence, because they lead to inconsistencies, where contradictory propositions can both be proved true.

Metaphysics of Ethics

In the `Metaphysics of Ethics (1797)` Kant described his ethical system based on the assumption that `reason` is the final authority for morality. As such any actions must be governed by a sense of duty, but rationalized by reason. The corollary to this argument is that an immoral action taken on the pretext of obedience to law or custom cannot be justified.  Kant described two imperatives of reason, but states only the latter is a basis for moral action:

  • the hypothetical imperative, which dictates a given course of action to reach a specific end;

  • the categorical imperative, which dictates a course of action that must be followed because of its rightness and necessity.

Kant's ethical ideas are a logical outcome of his belief in the fundamental freedom of the individual, as stated in his work `Critique of Practical Reason (1788)`. This freedom was not the freedom of anarchy, but rather as the freedom of self-government, the freedom to obey the moral laws of the universe as dictated by reason.

General Natural History and Theory of the Heavens

Kant also published a major work related to cosmology in 1755, entitled `General Natural History and Theory of the Heavens`. This work was originally published anonymously, for although there was general acceptance of Newtonian mechanics, Kant's work was starting to move towards a more divisive view of secular cosmology. While Newton is often called the `father of modern physics`, he was a man still rooted in the beliefs of his own times and, as such, his view of cosmology still demanded the ever-present hand of God. So, in this respect, Kant cosmology could have been seen as a contradiction to the Newton-Christian view of natural design. However, Kant was continuing a process that was removing the need for divine interference; whereas Newton still required God to regularly infuse nature with new motion and would invoke God, whenever physical explanations failed, as in the case of the ecliptic orbits. Whereas, Kant was to subsequently learn that the planetary orbits, based on an ecliptic plane, resulted from forces acting on particles that had accreted into a spinning cloud. Within the scope of this explanation, Kant did not have to appeal to God in this matter. However, it needs to be highlighted that Kant's philosophical position does not reject God. While Kant's ideas of God are buried in many convoluted descriptions, they appear to hold to a notion of a `necessary being`, which is the architect of order rather than a creator to whom all other freewill is subject. However, for all its apparent sophistication, a parallel with Aristotle's idea of a `prime mover` can still be drawn.

Kant's universe was based on the notion that the forces of nature are goal-directed and energy `unfolds` within the cosmos to create complex structures. This unfolding has both process and purpose. However, purpose is not imposed by a supernatural force, but rather woven into the very fabric of the universe. By this means, matter has an inherent ability to take shape, which in-turn gave rise to order and biological diversity that we now see in the universe. Given purpose, the processes of nature are driven by the forces of attraction and repulsion to generate both harmony and beauty. Within this model of cosmology, Kant likened the universe to the `chain of nature` and describes humanity as but one link in the chain. As such, there is nothing unique in humanity and as a result Kant is led to the conclusion that the claim that "a universe created for humanity is both exaggerated and provincial". In fact, Kant uses an analogy in which a louse on the scalp of a person's head might suggest the scalp had to have been created for the sake of its own happiness. So philosophical, Kant surmises that within this chain of nature, all beings are equal and nature has no preference. Ultimately, the goal of nature is biodiversity and the purpose of the planets is to sustain life. This process must have led Kant to the following question:

What is the purpose of life?

If we follow Kant's argument, the unfolding of nature evolves towards both process and purpose. As such, this universal purpose must ultimately lead to intelligent life throughout the universe. As a consequence, Kant conjectures on the existence of more intelligent forms of extraterrestrial life. However, it has to be said, without elaborating on the details, that some of Kant's ideas in this area were highly speculative and even somewhat bizarre. Therefore, it is possibly more useful to follow this line of reasoning, regarding the purpose of life, into the area of freewill. If humanity is an integral part of chain of nature, its process and purpose must be linked to nature:

So how are human actions free, while natural processes are predictable?

Certainly, Kant raised many arguments in an attempt to resolve this dilemma linked to the apparent deterministic causality of nature in contrast to human freewill. However, even today, the whole nature of human cognition is still an open question and one that we will return to, when our overall perspective has expanded.