The Rationalists, principally Descartes, Spinoza, and Leibniz, approached the problems of human knowledge from another angle. They hoped to escape the epistemological confines of the mind by constructing knowledge of the external world, the self, the soul, God, ethics, and science out of the simplest, indubitable ideas possessed innately by the mind. Leibniz in particular, thought that the world was knowable a priori, through an analysis of ideas and derivations done through logic. Super-sensible knowledge, the Rationalists argued, can be achieved by means of reason. Descartes believed that certain truths, that "if I am thinking, I exist," for example, are invulnerable to the most pernicious scepticism. Armed with the knowledge of his own existence, Descartes hoped to build a foundation for all knowledge.
Descartes believed that he could infer the existence of objects in space outside of him based on his awareness of his own existence coupled with an argument that God exists and is not deceiving him about the evidence of his senses. Kant argues that knowledge of external objects cannot be inferential as it establishes subjective experiences. It does not follow that one has the capacity to be aware of one's own existence in Descartes' famous cogito argument as it already presupposes that existence of objects in space and time outside of me.
Leibniz argued that the ways we thought were embedded into our reason and not obtained through the world and that substance is obtained independently of appearance and is a result of substantial reality. He argued that monads (atoms) are building blocks of reality and used the principle of discernability to demonstrate that reason tells us matters of substance and it is independent of any person’s experience of it. Reason can establish objectivity and the world can be understood through a matter of rationality.
Kant's answer to the problems generated by the two traditions mentioned above changed the face of philosophy.
First, Kant argued that that old division between a priori truths and a posteriori truths employed by both camps was insufficient to describe the sort of metaphysical claims that were under dispute. An analysis of knowledge also requires a distinction between synthetic and analytic truths. In an analytic claim, the predicate is contained within the subject – ‘all bachelors are unmarried men’. The subject of a synthetic claim, however, does not contain the predicate- ‘all bachelors are lonely’.
The central question of metaphysics in the Critique of Pure Reason reduces to "How are synthetic a priori judgments possible?" (19) If we can answer that question, then we can determine the possibility, legitimacy, and range of all metaphysical claims.
Kant argues that a number of synthetic a priori claims, like those from geometry and the natural sciences, are true because of the structure of the mind that knows them. "Every event must have a cause" cannot be proven by experience, but experience is impossible without it because it describes the way the mind must necessarily order its representations.
Kant had come to doubt the claims of the Rationalists because of what he called antinomies, or contradictory, but validly proven pairs of claims that reason is compelled toward. From the basic principles that the Rationalists held, it is possible, Kant argues, to prove conflicting claims like, "The world has a beginning in time and is limited as regards space," and "The world has no beginning, and no limits in space." (A 426/B 454) Kant claims that antinomies like this one reveal fundamental methodological and metaphysical mistakes in the rationalist project. The contradictory claims could both be proven because they both shared the mistaken metaphysical assumption that we can have knowledge of things as they are in themselves, independent of the conditions of our experience of them.
The Antinomies can be resolved, Kant argues, if we understand the proper function and domain of the various faculties that contribute to produce knowledge. We must recognize that we cannot know things as they are in themselves and that our knowledge is subject to the conditions of our experience. The Rationalist project was doomed to failure because it did not take note of the contribution that our faculty of reason makes to our experience of objects. Their a priori analysis of our ideas could inform us about the content of our ideas, but it could not give a coherent demonstration of metaphysical truths about the external world, the self, the soul, God, and so on.
Kant's methodological innovation was to employ what he calls a transcendental argument to prove synthetic a priori claims. Typically, a transcendental argument attempts to prove a conclusion about the necessary structure of knowledge on the basis of an incontrovertible mental act. Kant argues in the Refutation of Material Idealism that "There are objects that exist in space and time outside of me," (B 274) and we have to transcend the real world in the order to understand freedom. Kant argues that we are governed by the law of practical reason, which in turn, explains the empirical world and the intuitions about ones self.
The first fundamental aim of moral philosophy, and so also of the Groundwork, is to “seek out” the foundational principle of a metaphysics of morals. Kant pursues this project through the first two chapters of the Groundwork. He proceeds by analyzing and elucidating commonsense ideas about morality. The point of this project was to come up with a precise statement of the principle or principles on which all of our ordinary moral judgments are based. The judgments in question here are supposed to be those any normal, sane, adult human being would accept.
In the third and final chapter of the Groundwork, Kant takes up his second fundamental aim, to “establish” this fundamental moral principle and show that it is a principle of rationality, his conclusion is not meant to answer a skeptical challenge. Kant rests this second project on the position that we — or at least creatures with rational wills — possess autonomy. His argument in this regard does often appear to try to reach out to a metaphysical fact about our wills. However, the most important elements of his argument to establish the fundamental principle of morality rest on a claim that the autonomy of our wills is a presupposition of any practical point of view recognizable as such by us.
Kant also believes that there are other aims of moral philosophy, such as addressing the question: ‘what ought I to do?’ and an answer to that question requires much more than delivering the fundamental principle of morality. We also need some account of the nature and extent of our various ethical obligations. To this end, Kant employs his findings from the Groundwork in The Metaphysics of Morals, offering a categorization of our basic ethical obligations to ourselves and others. Moral philosophy should also characterize and explain the demands morality makes on human psychology and forms of human social interaction.
A basic theme is that the fundamental philosophical issues must be addressed a priori, that is, without drawing on observations of human beings and their behavior. Once we “seek out and establish” the fundamental principle of morality a priori, then we may consult facts drawn from experience in order to determine how best to apply this principle to human beings and generate particular conclusions about how we ought to act.
Kant holds that the fundamental principle at the basis of all of our moral duties is a categorical imperative. It is an imperative because it is a command (e.g., “You must not lie.”) More precisely, it commands us to exercise our wills in a particular way, not to perform some action or other. It is categorical in virtue of applying to us unconditionally, or simply because we possesses rational wills, without reference to any ends that we might or might not have. It applies to all rational beings as is a formula of universal law: ‘I ought never to act except in such a way that I could also will that my maxim should become a universal law’ (p.15).
There are ‘oughts’ other than our moral duties however, but these oughts are distinguished from the moral ought and is based on a principle that is a hypothetical imperative. A hypothetical imperative is a command that also applies to us in virtue of our having a rational will, but not simply in virtue of this. A hypothetical imperative is thus a command in a conditional form where the subject matter is contained within the predicate. ‘Anyone wills the end, wills the means’ and it will not give us synthetic a priori reason as it is analytic..
The argument for the first formulation of the categorical imperative is that a command of morality binds unconditionally and is supposed to yield the formula of the universal law. We have seen that in order to be good, we must remove inclination and the consideration of any particular goal from our motivation to act. The act cannot be good if it arises from subjective impulse. If we remove all subjectivity and particularity from motivation we are only left with will to universality. What we must do in any situation of moral choice is act according to a maxim that we would will everyone to act according to.
There is one other formulation of the Categorical Imperative that has been quite influential in ethical discussion, the so-called End-in-Itself Formulation. Kant stated it in the following manner:
‘So act as to treat humanity, whether in your own person or in that of any other, in every case as an end, never as a means only’
Here we return to Kant's fundamental point: we are obligated to respect the humanity, the human worth, of others by our actions. A combination of the formula of universal law and formula of humanity is supposed to yield the Formula of Autonomy. This law assumes that the source of normativity is external to the rational will and provides us with the concept of the kingdom of ends, where every rational being is a member with dignity and autonomy.
Kant argued that the moral status of an action is not determined by its consequences. We are not morally obligated to seek the best overall outcome by our actions, but rather we are obligated to perform those actions that accord with our moral duty--the fundamental demand that we should treat others, and ourselves, in a manner that is consistent with human dignity and worth. Thus if, for example, lying to another person might lead to a better outcome overall than telling the truth, we would still be obligated not to lie because the act of lying does not respect the humanity of the person to whom we tell the lie.
Kant’s philosophy is still topical and relevant to debate even in today’s society. One of the first major challenges to Kant's reasoning came from the philosopher Benjamin Constant, who asserted that since truth telling must be universal, according to Kant's theories, if asked, one must tell a known murderer the location of his prey. This challenge occurred while Kant was still alive, and his response was the essay On a Supposed Right to Tell Lies from Benevolent Motives. In this reply, Kant argued that it is indeed one's moral duty to be truthful to a murderer, which is a result that deeply conflicts with many people's moral intuitions.
Therefore, Kant argued that it is indeed one's moral duty to be truthful to a murderer, which is a result that deeply conflicts with many people's moral intuitions.
Kant argued that telling the truth to the murderer is required because the action itself is of value, regardless of the consequences; lying to the murderer would treat him as a means to another end, which is immoral because the will would be acting only under a particular interest, and not one that has universality. Furthermore, one does not know what will happen in the future. It might turn out that if you lied about where the victim is, you would be morally responsible for that lie. For example, say you said the victim was in the park, when you thought he was in the library. However, little did you know, the victim actually left the library and went to the park. The lie would actually lead the murderer to the victim..
Kant offers an account of human rationality that is essentially oriented towards judgment and Kant’s analysis of moral intuitions and the idea of a rational agent as a self-governing being still has contemporary relevance today. I believe that Kant’s theory sets a high ideal of conduct to follow and as result, his theory on ethics and the hope of identifying universal principles remains the paradigmatic and most influential attempt to do so.
