The Argument from Laws of Nature (a) The Analysis of Argument

In the above argument, the Copernican model of mind and world is presupposed. Therefore, it can be seen as establishing a conditional claim that if a priori concepts determine objects, then objects are representations. It fails to establish the truth of idealism independently from the reality of a priori concepts.

135 Nevertheless, in Transcendental Deduction Kant proposes an independent argument from laws of nature for idealism that does not presuppose the conclusion from his idealistic view of space and time.¹⁶⁶ At the very end of the Second Section of Deduction in 1781 Critique Kant writes:

That nature should direct itself according to our subjective ground of apperception, indeed in regard to its lawfulness even depend on this, may well sound quite contradictory and strange. But if one considers that this nature is nothing in itself but a sum of appearances, hence not a thing in itself but merely a multitude of representations of the mind, then one will not be astonished to see that unity on account of which alone it can be called object of all possible experience, i.e., nature, solely in the radical faculty of all our cognition, namely, transcendental apperception; and for that very reason we can cognize this unity a priori, hence also as necessary, which we would certainly have to abandon if it were given in itself independently of the primary sources of our thinking. For then I would not know whence we should obtain the synthetic propositions of such a universal unity of nature, since in this case one would have to borrow them from the objects of nature itself. But since this could happen only empirically, from that nothing but merely contingent unity could be drawn, which would fall far short of the necessary connection that one has in mind when one speaks of nature. (A114)

The argument could be reconstructed as follows:

(1) Nature consists either of things in themselves or of representations.

(2) If nature consists of things in themselves, then we would have no a priori knowledge of the laws of nature.

(3) We have synthetic a priori knowledge of the laws of nature.

(4) Nature does not consist of things in themselves.

(5) Nature consists of representations.

Assuming some modal truth, the argument starts from an exclusive disjunction on the metaphysical status of nature and then proceeds to idealism in virtue of the incompatibility of the modal truth with metaphysical realism.

Despite its independence, the basic structure of the argument from laws of nature is not something new. In fact, this argument is nothing but a dynamic parallel to the argument from geometry. Like geometrical truths, laws of nature are also expressed in synthetic a priori proposition.

166 Guyer acutely notes it. See Guyer 1987, 379-382.

136 Like other epistemic arguments for idealism, Kant’s argument rests on the crucial epistemic assumption of our knowledge of laws of nature. It might raise the doubt whether Kant is virtually making such an outright assumption or not. This doubt can be dispelled by Kant’s note in his own copy of Critique: “the laws of nature really have their origin in the understanding, and are just as little to be encountered outside it as space and time are, is already proved by the in any case already acknowledged assertion that we cognize them a priori and as necessary[.]”¹⁶⁷ Here Kant does not only underline the parallel between space/time and laws of nature, but he makes explicit the a priori claims are well-established.

(b) Human Legislation and Ontological Degeneration

The argument from laws of nature differs from the argument from geometry in its emphasis on the idea of legislation and its presupposition of the agency. Kant discusses the idea of legislation in many places:

Now we can characterize it as the faculty of rules. This designation is more fruitful, and comes closer to its essence. Sensibility gives us forms (of intuition), but the understanding gives us rules. (A126)

…Rules, so far as they are objective (and thus necessarily pertain to the cognition of objects) are called laws. (A126)

… The understanding is [thus not merely a faculty for making rules through the comparison of the appearances; it is itself] the legislation for nature, i.e., without understanding there would not be any nature at all[.](A126)

The idea “understanding as legislation for nature” marks one significant difference from both the old space arguments and the epistemic argument from geometry. Kant’s idealism is distinctive.

Firstly, metaphysical idealism rests on space idealism. Physical objects are representations in virtue of space as the form of sensibility. Second, the premise of Kant’s argument starts from our possession of a body of knowledge, rather than from the nature of sensibility. In Transcendental Aesthetic, Kant’s identification of space as the form of sensibility obscures the very distinctive character of Kant’s idealism. It is in the argument from legislation that the distinctiveness of Kant’s idealism achieves its peak. On the one hand, the argument from laws of nature does not start with the nature

167 In Kant’s works the notion of laws of nature is closely connected with that of experience.

137 of sense-perception, as the four old space-arguments do. On the other hand, it does not result in any theory of sensibility, as the argument from geometry does.

The step to idealism is decisive. Kant concedes to the elusiveness of the idea of legislation by human understanding¹⁶⁸, and he claims that it is “[in]comprehensible” (A113), “contradictory and strange” (A114), “exaggerated and contradictory” (A127). However, why does Kant soon claim

“[o]n my principles it is easily comprehensible” (A113) and “one will not be astonished” (A114)?

Why can the extraordinary idea of human legislation of nature be saved by idealism?

In my view, the key to the solution to this puzzle is the idea of an ontological degeneration that both of the above arguments presuppose. Traditionally, the ontological hierarchy has different levels: on the top, it is the infinite divine entity; in the middle, it is finite concrete entities; and on the bottom it is mental entities. The view is that the ontological status of physical objects degenerates to the mental entities, namely, from the middle to the bottom of the ontological hierarchy.

Leibniz notes that there is an analogy between God and human beings. In his Discourse on Metaphysics in 1686 Leibniz writes that “created substances depend upon God, who preserves them and who even produces them continually by a kind of emanation, just as we produce our thoughts”¹⁶⁹. In his later Principles of Nature and of Grace in 1714 Leibniz elaborates this idea in more detail:

It is not only a mirror of the universe of created things, but also an image of the divinity. The mind not only has a perception of God’s works, but it is even capable of producing something that resembles them, although on a small scale. For to say nothing of the wonders of dreams, in which we effortlessly (but also involuntarily) invent things which we would have to ponder long to come upon when awake, our soul is also like an architect in its voluntary actions; and in discovering the sciences according to which God has regulated things (by weight, measure, number, etc.), it imitates in its realm and in the small world in which it is allowed to work, what God does in the large world. (1989, 46)

As Leibniz observes, there exists a striking analogy between God and human beings despite their essential difference: God is the producer of the physical objects in the universe; likewise, we human beings are the producers of thoughts in our mind. In the dream we can invent things effortlessly, and the effortless invention puts us in a position akin to God, where God creates physical things effortlessly. Therefore, the way we have the dominance over our mental world is analogous to the way God has dominance over the physical world.¹⁷⁰

168 The talk of the laws of nature and the talk of a priori determination are essentially expressing the same thing.

169 See Leibniz 1989, 211-212.

170 The above ontological hierarchy is about God, physical entities and mental entities. In another direction, the ontological hierarchy could be developed making use of the ambiguity of the term “idea”, which has nothing to do

138 Leibniz calls into attention the analogy between God and human beings in order to demonstrate the thesis that the human mind is qualitatively similar to, yet quantitatively inferior to, God. This is the famous doctrine that man is made in God’s image. The world is created by God.

It is our resemblance to God that explains the intelligibility of the world to us.¹⁷¹

Different from Leibniz, Kant’s focus is not on the creator role of God, but on the legislator role of God. This move is understandable, since even sensible representations are not created by our human beings. For those who admit the existence of laws of nature is not sui generis. Rather, the notion of legislation implies the existence of a legislator. Traditionally, it is God who lays the laws for nature. The theological dependence of laws of nature on a law-maker is compatible with their mind-independence. According to this view, laws of nature are things in themselves. In an important way, human beings have their dominance over the mental not in the sense of producing representations, but in the sense of ordering representations.

Taken in itself, the epistemic or mental atheism that God does not have dominance over any mental state is not harmful to many philosophers. Even Leibniz is adherent to some weak version of it. However, when combined with the Kantian idealism of nature, epistemic atheism entails natural atheism that God plays no role in nature. Kant’s philosophical radicalism precisely lies in the idea of legislation of nature by understanding: for Kant, we do not resemble God; rather, we replace God.

In my view, the legislation of nature by understanding has a twofold significance. According to the traditional interpretation, the attribution of the legislative role to human understanding marks the culmination of the Copernican Revolution. As far as the relation of representation to object is concerned, Kant’s Copernican Revolution suggests that we should think the other way around. I contend that we could consider the issue from a different point of view. As far as the relation of the human to the divine is concerned, the legislation of human understanding marks the ascending of the human and the retreating of the divine.

(c) The Structure of Argument: Kantian Disjunctive Syllogism

with the order and law. The notion idea is ambiguous in early modern philosophy. Leibniz has already noted the problematic ambiguity of the notion of idea. One the one hand, it refers to the mental entities, and, one the other hand, it refers to the abstract entities. The two conceptions of ideas are developed respectively by Locke and Malebranche, the two most preeminent successors to Descartes’ theory of ideas are. The abstract Platonic Ideas are God’s Idea, while the Lockean ideas are human ideas. The ambiguity of ‘idea’ also constitutes an analogy between God and human beings.

171 For the doctrine that man is made in God’s image in modern philosophy see Craig 1996.

139 In the following, I will say something about the general structure of Kant’s argument for mind-dependence. What characteristic of Kant’s arguments for idealism is the argumentative strategy one might call “Kantian disjunctive syllogism”.

Influenced by Leibniz, German metaphysical tradition attaches great importance to conceptual analysis and deductive proof. The syllogism is universally regarded as the paradigmatic of deductive reasoning of logical validity. In fact, the syllogism is one of the most frequent techniques employed by German rationalist philosophers in building baroque metaphysical system.

Since many systems of metaphysics start with a conceptual distinction, and the conceptual distinction is apt to function as the major premise of a disjunctive syllogism, it is no wonder why disjunctive syllogism is pervasive in rationalist metaphysics. The disjunctive syllogism of the form is as follows:

(1) Major premise: Either P or Q.

(2) Minor Premise: Not P (3) Conclusion: Q

What is distinctive of Kantian Disjunctive Syllogism is the Minor premise. The truth of the Minor premise is often deduced by modus tollens.

(1) If R, then S.

(2) Not S.

(3) Not R.

The sub-argument by modus tollens consists of a conditional claim and a negation claim. The conditional claim is often a plausible theoretical truth. The negative claim is normally a modal truth.

Again here we encounter a negative claim “Not S”. The most characteristic feature of a Kantian disjunctive claim is that “Not S” is a modal truth. This modal truth is often assumed without justification. When Kant is charged with begging the question of his opponents, it is this modal truth that is called into question.

140 The Kantian disjunctive syllogism instantiates the following scheme:

(1) Either P or Q.

(2) If P, then R.

(3) Not R.

(4) Not P (5) Q

The paradigmatic Kantian disjunctive syllogism is the famous argument from science to idealism. The argument from laws of nature under discussion is also paradigmatic, though it is less known. The argument from the Copernican model to idealism is one complicated version of Kantian disjunctive syllogism.

(1) Either P or Q.

(2) If P, then either R or S.

(3) Not R.

(4) Not S.

(5) Not P. (from (2), (3), and (4) by modus tollens) (6) Q

The distinctive feature of this argument is that the rejection of the disjunct P is made in virtue of a new dilemma, not in virtue of an incompatibility.