Crusius and the Pre-critical Kant on the Principle of Determining Reason and the Ontological Argument
Crusius y el Kant precrítico sobre del Principio de Razón Determinante y el Argumento Ontológico
IGNACIO GARAY*
Recibido: 23/01/2023. Aceptado: 24/08/2023.
* Profesor / Investigador en Universidad Internacional de La Rioja. Líneas de investigación: Teología Filosófica – Argumentos a favor y en contra de la existencia de Dios – Argumento Ontológico. Contacto: juanignacio.garay@unir.net. Publicaciones recientes: Garay, Ignacio. 2022. “Christian Wolff y la ontología”, Sapientia, volumen LXXVII, Nº 249, 175-229. (ISSN: 0036-4703). Garay, Ignacio. 2022. “Santo Tomás y Crusius, frente a Kant y los racionalistas”, Espíritu, LXXI, Nº 164, 2022, 81-101.
Abstract: In his version of the so-called Thomistic objection against the ontological argument, Kant follows Crusius in replacing the term “sufficient” for “determining” in the formulation of the ‘principle of reason’ as an attempt to distinguish logical possibility from real possibility more clearly. However, their respective reformulations of this principle and the Thomistic objection present some significant differences. In this paper, I will try to show two things: 1) The main differences between Crusius’ and Kant’s reformulation of the principle of reason. 2) The way in which these differences affect their respective formulations of the objection against the ontological argument.
Keywords: Crusius – Kant – Ontological argument – Principle of reason
Resumen: En su versión de la llamada Objeción Tomista contra el argumento ontológico, Kant sigue a Crusius al reemplazar el término “suficiente” por “determinante” en la formulación del ‘principio de razón’ para distinguir más claramente la posibilidad lógica de la posibilidad real. Sin embargo, sus respectivas formulaciones de ese principio y de la Objeción Tomista presentan algunas diferencias significativas. En este artículo, trataré de mostrar dos cosas: 1) Las principales diferencias entre las formulaciones del ‘principio de razón’ realizadas por Crusius y por Kant. 2) La forma en que estas diferencias afectan a sus respectivas objeciones contra el argumento ontológico.
Palabras clave: Crusius – Kant – Argumento ontológico – Principio de razón
1. Introduction
During his pre-critical period, Kant made two objections against the ontological argument: 1) The so-called ‘Thomistic objection’, according to which from the fact that the notion of existence is included in the concept of God it does not follow that God exists in reality; 2) The so-called ‘Empiristic objection’, according to which, given that existence is not a real predicate, existence is not included in the notion of any being.1 The first objection is similar to Christian August Crusius’ objection to the ontological argument presented in his Entwurft (Crusius, Ch. A. 2006).2 Both authors base their objections on a reformulation of the ‘principle of reason’ that allows for a distinction between the ‘reason of being’ and the ‘reason of knowing’.3
In his reformulation of the ‘principle of reason’, Kant follows Crusius in replacing the term ‘sufficient’ for ‘determining’, as an attempt to distinguish logical possibility from real possibility more clearly. Although both agree that, in order to make this distinction correctly, the principle of determining reason must be reformulated in terms of the ‘determining reason of being’ and the ‘determining reason of knowing’, their respective reformulations present some significant differences. Due to these differences in their respective reformulation of the principle of determining reason, Crusius’ and Kant’s objections to the ontological argument, based on the distinction between ‘reason of being’ and ‘reason of knowing’, are not exactly the same.
Some scholars in recent times, like Kanzian (2009),4 Boehm (2016),5 Perin (2015)6 and Longuenesse (2001),7 among others,8 as well as the classical writing by Heimsoeth (1926),9 have made substantial contributions concerning Kant’s ‘principle of reason’ from different perspectives. In this paper, I will take for granted the core of their findings and will not disagree with them. Instead, I will try to focus on two things: 1) The main differences between Crusius’ and Kant’s reformulation of the principle of determining reason. 2) The way in which these differences affect their respective formulations of the objection against the ontological argument.
2. Crusius’ reformulation of the principle of reason
Crusius is known for leading the pietistic opposition against the philosophical tradition initiated by Leibniz and Wolff, which would culminate with Kant.10 One of the main ideas of Crusius’ opposition to the Leibnizian-Wolffian rationalism is the accusation that the power of reason has been exaggerated.11 According to Crusius, due to this exaggeration, the logical and the ontological orders could not be properly distinguished. This confusion could lead to serious mistakes, such as the denial of human freedom. In order to bring reason back within its limits, Crusius makes two moves: 1) He rejects the identification between the mathematical and the philosophical method, and 2) He redefines the principle of reason in such a way that, in considering the distinction between the two orders more properly, it does not eliminate human freedom.12 This reformulation is also the basis for his objection against the ontological argument.
Crusius’ reformulation of the principle of reason does not respond to a merely theoretical discrepancy between his philosophy and the Leibnizian-Wolffian tradition, but rather to the fact that he sees an inevitable tendency to determinism in the principle of sufficient reason as presented by this tradition, as has already been mentioned.13 Therefore, the principle of sufficient reason should be called ‘principle of determining reason’ and the principle of sufficient reason should be redefined in terms compatible with freedom. In De usu, Crusius states that, for both Leibniz and Wolff, a ‘sufficient reason’ is a reason that allows one to understand why something exists, and why it exists in one way and not in another (§1 DU). If this is so, this principle should not be called ‘principle of sufficient reason’, but rather ‘principle of determining reason’. Indeed, given that ‘to determine’ is to actualize one way of existing of a thing, excluding every other, once a way of existing of a thing is determined, that thing cannot exist in any other way (§3 DU). Therefore, if this principle is not restricted, it introduces absolute necessity in everything that exists (§5 DU) and eliminates free will and moral responsibility (§8 DU). As we will see further on, when Kant redefines the ‘principle of reason’, he does not have this moral motivation. In fact, he explicitly disagrees with Crusius’ analysis as regards to freedom.
Aiming to preserve the existence of free will and to keep determinism within the boundaries of the physical world, Crusius elaborates a very complex division of the ‘principle of reason’. I will explain here only the aspects of this division that are useful for understanding Cursus’s objection to the ontological argument.
In the first place, Crusius distinguishes the ‘reason of physical existence’ from the ‘reason of moral existence’. The former refers to the reason that explains why things physically exist or can exist. The latter refers to the reason according to which things should be done one way or another (§34 DU). The ‘reason of physical existence’ is divided in two: the ‘principle of being’ (essendi) and the ‘principle of knowing’ (cognoscendi). The former refers to a thing considered in itself, existing outside the understanding. This obtains, for example, when we say that God is the reason for the world. The latter refers to the reasons that allow us to know something. This would explain why we know that one concept follows from another. For example, when we say that God’s supreme perfection is the reason of his eternity (§35 DU).
The first distinction, between the ‘reason of physical existence’ and the ‘reason of moral existence’, allows Crusius to preserve free will and determinism of the physical world at the same time. This is because human actions are ruled by the ‘principle of reason of moral existence’,14 which is compatible with freedom. However, the physical world is ruled by the ‘principle of reason of physical existence’ (§26 DU), which guarantees determinism.
The second distinction, between the ‘reason of being’ (which includes the ‘principle of efficient cause’) and the ‘reason of knowing’, will allow Crusius to say, against the ontological argument, that even if the concept of the perfect being includes existence, this is only the reason of knowing, but not the reason of being. And so, the existence of God cannot be proven this way, as we will see further on.
3. Kant’s reformulation of the principle of reason
Kant’s reformulation of the ‘principle of reason’,15 on which his first objection against the ontological argument is based, is developed in his Nova Dilucidatio (Kant, 1922, 1:385-416).16 Here Kant does not have the same moral motivation of Crusius, as we will see, but he follows him in replacing the term ‘sufficient’ for ‘determining’ (IV ND) and both reformulations share the following intuition: in order to make inferences concerning the real world, we should postulate a principle independent from the ‘principle of contradiction’. However, the division of the ‘principle of determining reason’ proposed by Kant is much simpler than Crusius’.17 In addition, he uses some terms with a different meaning, as we will soon see.18
Kant starts his analysis by explaining that, “to determine is to posit a predicate while excluding its opposite” (IV ND), as Crusius did. At the same time, he distinguishes the ‘antecedently determining reason’ (reason of being) from the ‘consequently determining reason’ (reason of knowing) also in a similar way to Crusius’ (§3 DU).
That which determines a subject in respect of any of its predicates, is called the ground. Grounds may be differentiated into those which are antecedently determining and those which are consequentially determining. An antecedently determining ground is one, the concept of which precedes that which is determined. That is to say, an antecedently determining ground is one, in the absence of which that which is determined would not be intelligible. A consequentially determining ground is one which would not be posited unless the concept which is determined by it had not already been posited from some other source. You can also call the former the reason why, or the ground of being or becoming, while the latter can be called the ground that, or the ground of knowing (IV ND).19
In other words, the notion of reason refers to a link between a subject and any of his predicates. Furthermore, that link can be held in the sphere of being (in that case, it is called ‘antecedently determining reason’), or in the sphere of knowledge (and, in that case, it is called ‘consequently determining reason’). He illustrates this distinction with the example of the eclipses of Jupiter’s satellites. Thanks to those eclipses we know the fact of the diffusion of light. However, this constitutes only the ‘consequently determining reason’, that is, the reason why we arrived at that truth. Indeed, even if Jupiter didn´t have any satellites, the light would diffuse anyway, whether we knew that truth or not. The case of the ‘antecedently determining reason’ is different, because it concerns the reason why light spreads; without this reason, that determination would not take place (IV ND).
So far, it seems that Kant’s reformulation of the ‘principle of reason’ is only trying to draw the same distinction between the logical and the ontological order proposed by Crusius. However, Kant further defines the scope of the principle, restricting it to only contingent existent things. Indeed, nothing that exists contingently can exist without a reason that determines its existence.20 The only necessary being is the only one that is not ruled by this principle, and so, the principle does not extend to every possible being.
First of all, namely, I had carefully to distinguish between the ground of truth and that of existence, although it might have seemed that the universality of the principle of the determining ground, which holds in the realm of truths, might equally extend over existence as well. […] But, in the case of existing things, it is necessary to search for the antecedently determining ground. If there be no such ground, then the being in question exists absolutely necessarily (VIII ND).
This means that the ‘principle of determining reason’ has universal scope in the field of knowledge. Therefore, a ‘consequently determining reason’ can be found for everything, and this principle is sufficient to establish a truth. On the contrary, in the field of being, only that which exists contingently has an ‘antecedently determining reason’, that is, a cause; if there exists something that does not have one, then this thing exists necessarily.21 This restriction to the principle of reason of being only to contingent things does not appear explicitly in Crusius.22 However, it will play an important role in distinguishing the different ways in which the two authors present their objections against the ontological argument, as we will see.
Finally, it´s clear that Kant’s division of the ‘principle of reason’ is much simpler than Crusius’, as has been said. This is because they also disagree about the scope of the ‘principle of reason of being’ regarding human actions. As we have already shown, for Crusius, free actions are ruled by the ‘principle of reason of moral existence’. However, this principle is different from the ‘principle of being’, which belongs to the ‘principle of reason of physical existence’, which governs physical world determinism. Nevertheless, Kant contradicts Crusius in this point, by arguing that free actions also have their ‘reason of being’.
So, too, in the case of the free actions of human beings: in so far as they are regarded as determinate, their opposites are indeed excluded; they are not, however, excluded by grounds which are posited as existing outside the desires and spontaneous inclinations of the subject, as if the agent were compelled to perform his actions against his will, so to speak, and as a result of a certain ineluctable necessity. On the contrary, it is in the very inclination of his volitions and desires, in so far as that inclination readily yields to the blandishments of his representations, that his actions are determined by a fixed law and in a connection which is most certain but also free. It is not a difference in the nature of the connection or the certainty which constitutes the distinction between physical actions and those possessed of moral freedom, as if these actions alone, subject to doubt in respect of their futurition and exempt from the chain of grounds, had a vague and indeterminate ground of coming to be. For, if that were the case, such actions would scarcely deserve to figure among the prerogatives of intelligent beings. But the way in which the certainty of their actions is determined by their grounds gives us all the room we need to affirm that they bear the characteristic mark of freedom. For such actions are called forth by nothing other than motives of the understanding applied to the will, whereas in the case of brute animals or physico-mechanical actions everything is necessitated in conformity with external stimuli and impulses and without there being any spontaneous inclination of the will (IX ND).
According to Kant, even free actions have a ‘reason of being’, not in an external being, but in the intelligence and the influx of will.23 Therefore, it is not necessary to postulate another principle different from the ‘principle of being’ to explain human actions without introducing absolute necessity into them and eliminating moral responsibility.24
4. Crusius’ objection against the ontological argument
Beside its implications in the moral field, Crusius’ reformulation of the ‘principle of reason’ also has a primary role in his objection against Leibniz’s and Wolff’s formulation of ontological argument, both based on that same principle. This objection is explained in his Natural Theology, the second part of his Entwurft. According to Crusius, only a posteriori demonstrations of the existence of God are possible. This is because any reasoning that starts from the field of concepts, arrives to its conclusion also only in the field of concepts, and it is impossible to infer any real existence from it (§377 E). This is the reason why Crusius finds no problem in accepting that existence is included in the idea of the most perfect being:
That of which it is said that nothing greater can be conceived, must possess every perfection, and possess it in the highest conceivable degree. Given that existence itself belongs to the number of perfections, if we attribute the concept of infinite perfection to a thing, we also must attribute to it the concept of constant and necessary existence (§137 E).25
However, even if Crusius accepts that existence is included in the concept of the most perfect being, for him, this does not imply that we also must accept that this is a demonstration of the existence of God. According to Crusius, these kind of inferences, the ones that allow us to know that a concept is included in the notion of another concept, are ruled by the ‘principle of reason of knowing’. To recall, this is the reason why we know that one concept follows from another. Therefore, as these inferences are based on the ‘principle of contradiction’, they can only have consequences in the logical order, but not in the ontological one. On the contrary, in order to lead to real existence, deductions must be based on the ‘principle of efficient cause’, which belongs to the ‘principle of being’, which refers to a thing considered in itself, existing outside the understanding, as has already been explained.
Given that every existence can only be proved by a reasoning based on a relation of cause an effect, even demonstrations of the existence of God cannot be carried out a priori by a geometrical method and based only on the ‘principle of contradiction’. In contrast, they must be carried out a posteriori and based on the ‘principle of sufficient cause’.
§234. On the contrary, in the demonstration of the existence of God, since it is asked for an efficient cause of the world, at least the principle of sufficient cause must be employed (§31), and this principle, by virtue of the concept of sufficient cause, can´t be followed from the principle of contradiction […]. This may well be what atheists obscurely perceive when they assure that the existence of God cannot be geometrically demonstrated (§234 E).
That is to say, the existence of God cannot be proved by the geometrical way because conclusions based on the ‘principle of contradiction’ only have a formal validity. Therefore, they are useful only on the logical order, but not in the ontological one. The epistemological meaning of the notion of existence reached by a reasoning that starts from a priori concepts and is based only on the ‘principle of contradiction’ is merely logical, but not real.26 To confuse one with the other, as Crusius understands that Leibniz and Wolff do, constitutes an illegitimate step from the logical to the real order.
However, in order to satisfy the atheists in every possible way, some scholars had tried to prove the existence of God using exclusively the geometrical method and merely by the principle of contradiction. But it can be seen a priori that such a demonstration can´t be right and that it is impossible to know the existence of God in any other way than by his work. One of those attempts is the Cartesian demonstration, which tries to deduce the existence of God from the concept of the most perfect being, a concept which would include existence. That is why it is thought that just by demonstrating the possibility of the most perfect being, his existence would be patent by the principle of contradiction (§235 E).
This is the reason why Crusius holds the ‘Thomistic objection’ against the ontological argument and argues that it is a syllogism with four terms, that falls into an equivocation fallacy. The term ‘existence’ does not have the same meaning in the premises than in the conclusion. In the premises, it means ‘ideal existence’, since it means that existence is included in the idea of God. In the conclusion, on the contrary, it means ‘real existence’, in the sense that God exists in reality.
This reasoning must go like this: the being that has every possible perfection, has also existence. God is a being that has every possible perfection, and so, he also has existence. Therefore, there is a God. This reasoning can be deceiving because the first sentence is an axiom and the other one a definition. Except that in its form it is not right, but it is a syllogism with four terms. The term “has existence” means something different in the conclusion than in the major premise. In the last one, it refers to existence in the understanding because a concept in the understanding includes existence in itself in the sense that when it is thought it must be thought together with existence as a part of it. But in the conclusion, it refers to real existence outside the understanding. Both premises are ideal propositions, but the conclusion must establish a real proposition. That’s why there is indisputably more in the premises than in the conclusion. Hence, even if one has demonstrated the possibility of a being that has every perfection, the only thing that this reasoning proves is that it is real existence outside the understanding is possible. But the question whether such a being exists outside the understanding still remains (§235 E).
For Crusius, this leap in the argumentation constitutes an illegitimate step from the logical to the ontological order. This illegitimate step is due to the lack of clarity in the formulation of the Leibnizian-Wolffian ‘principle of reason’, which introduces a confusion between the ‘reason of being’ and the ‘reason of knowing’. As the former refers to a real thing outside the understanding, the latter only allows us to know that one concept follows from another. However, according to Crusius, in order to avoid this confusion, one must distinguish the properties that are attributed to a concept in the logical order from the properties that are attributed to a being in the real order. Therefore, based on this distinction, Crusius can agree with Leibniz and Wolff to the effect that in the concept of the most perfect being the notion of existence is included, but, at the same time, he can disagree with them in the fact that this inference proves that God exists in reality.27
§37. Sometimes we say that something is the reason for another thing, even if it is only the reason of knowing that thing […]. This has to be taken into account not to fall into confusion and think, for example, that, in postulating a concept from which another one can be easily derived, with that, the real reason of the thing represented in that concept has also been explained (§37 E).
Furthermore, for Crusius, although the argument that proves that the idea of a most perfect being includes existence is not a demonstration of the existence of God, nevertheless it is not totally useless. It is useful in order to argue that, once the existence of God is demonstrated, his existence is necessary. This means that, if a maximally perfect been exists, it must necessarily exist.28
But even if the existence of God cannot be proved by the concept of the most perfect being, the consideration that it includes existence has another utility. It shows that, as soon as every perfection is attributed to a thing that exists, then also necessary existence is attributed to that thing (§235 E).29
Kant will agree with Crusius in denying the possibility of a demonstration of the existence of God that moves from attributing existence to the idea of a perfect being to establishing its real necessary existence. However, in this text Crusius still maintains the idea that God is a necessary existent, because existence belongs to his essence, which Kant will deny. I think this difference is important because it shows that, for Crusius, there is still a link between maximal perfection and necessary existence. As we already said, if the concept of a perfect being includes necessary existence, once its existence has been established, the ontological argument can be used to prove that this being exists necessarily, because it has existence in its essence. The main contribution of this paper is that it is possible that Kant denied this and every possible link between maximal perfection and existence in order to also deny that something exists necessarily because it has existence in its essence, as we will see.
5. Kant’s objection against the ontological argument
As we have already seen, Kant follows Crusius in criticizing Wolff’s ‘principle of sufficient’ reason and in distinguishing the ‘reason of being’ from the ‘reason of knowing’. However, his critique is not just the ‘Thomistic objection’ from the Entwurft, since he also criticizes the notion, typical of the Leibnizian-Wolffian tradition, of God as the being that has the reason of its existence in its essence30.
Kant states that nothing can have its reason of existence in itself. However, if God is defined as the being that has the reason of his existence in his essence, this principle would be violated. Thus, given that nothing is its own cause, any argument that tries to prove the existence of God from the concept of the most perfect being is invalid. Consequently, according to Kant, the being that exists necessarily has no reason of its existence. We say that it ‘necessarily exists’ because it cannot be thought as non-existing. However, this is only the ‘reason of knowing’ of its existence, that is, the ‘consequently determining reason’, but not its ‘antecedently determining reason’:
I find, indeed, the view repeatedly expressed in the teachings of modern philosophers that God has the ground of His existence posited in Himself. For my part, I find myself unable to support this view. To these good men it seems, namely, somehow rather hard to deny that God, the ultimate and most complete principle both of grounds and of causes, should contain within Himself the ground of Himself. Thus they maintain that, since one may not assert that there is a ground of God which is external to Him, it follows that He contains concealed within Himself the ground of Himself. But there could scarcely be anything more remote from sound reason than this. For when, in a chain of grounds, one has arrived at the beginning, it is self-evident that one comes to a stop and that the questioning is brought to an end by the completeness of the answer. Of course, I know that appeal is made to the concept itself of God; and the claim is made that the existence of God is determined by that concept. It can, however, easily be seen that this happens ideally, not really. Form for yourself the concept of some being or other in which there is a totality of reality. It must be conceded that, given this concept, existence also has to be attributed to this being. And, accordingly, the argument proceeds as follows: if all realities, without distinction of degree, are united together in a certain being, then that being exists. But if all those realities are only conceived as united together, then the existence of that being is also only an existence in ideas. The view we are discussing ought, therefore, rather to be formulated as follows: in framing the concept of a certain Being, which we call God, we have determined that concept in such a fashion that existence is included in it. If, then, the concept which we have conceived in advance is true, then it is also true that God exists (VI ND).
So far, Kant’s reasoning is very similar to Crusius’. Both agree in that, while it is true that we have to confer existence to the concept of the most perfect being, it does not follow from that that it really exists. However, they disagree about the implications of this idea. On the one hand, at the end of his argument, Crusius states that if an argument proves that the concept of God is possible, it only proves that his existences is possible, but not real: “Even if one has demonstrated the possibility of a being that has every possible perfection, it has only been proved that its real existence is possible” (§235 E). On the contrary, Kant says that if an argument proves that the concept of God is possible, then it also proves that his existence is real: “If, then, the concept which we have conceived in advance is true, then it is also true that God exists” (VI ND). This statement by Kant is not far from Leibniz’s description of the ontological argument as a solid but incomplete demonstration. For Leibniz, Anselm’s proof is a valid argument, but it is not complete because the possibility of God has not been established. However, if it is shown that the idea of God is a possible or true idea, then the ontological argument proves that God exists in reality.31
The main contribution of this article is to pose that, possibly, Kant realized that, if it is shown that the idea of the most perfect being is a real idea, then the ontological argument is sound. And also, that if we accept that the idea of the most perfect being includes its existence, there is still a link that goes from the greatest perfection to necessary existence that could be held, not only in the ideal order, but also in reality. This is because if existence is included in the concept of the most perfect being, once its existence is proved, we must attribute to it necessary existence, as Crusius said. In that case, God would exist necessarily because his essence implies his existence, that is, because he has the reason of his existence in his essence. Now, this would contradict Kant’s claim that nothing can have its reason of existence in itself. In addition, it would make the idea of the being which has the reason of its existence in its essence a coherent one, which Kant finds absurd.
If this is so, in order to maintain that no being can have its reason of being in itself, one must state one of two things: 1) That the idea of a most perfect being, which implies existence, is not a real idea, or 2) That the idea of a most perfect being is a true idea, but it does not imply existence. The first option leads to atheism, because if the idea of God is not a true idea, then his concept is contradictory and his existence is impossible. Therefore, God would not exist.32 The second would lead one to state that maximal perfection does not imply existence as one of its perfections. That is to say, that the maximal perfection of the idea of God would not be the reason for this idea to imply existence. The only way to do this is to destroy every possible link between maximal perfection and necessary existence, denying that existence itself is a perfection. This way, if existence is not included in the concept of the most perfect being, even if its existence is proved, we will not be able to attribute to it necessary existence in the sense that it has the reason of his existence in its essence, as Crusius said.33 However, this would be the only way in which the same principle that holds that ‘nothing has the reason of its existence in itself’, would be valid both for the real order and for the ideal order as Kant supposed. It would be valid in the ontological order because nothing could be cause of itself. At the same time, it would also be valid in the logical order because no idea would imply existence. It is possible that Kant followed a line of reasoning similar to this one when he opted for the second option shortly after in Beweisgrund34 and stated that existence is not a real predicate or a perfection.35
6. Conclusion
As we have seen, Kant follows Crusius in a certain way in his first objection against the ontological argument. Both agree that, in the idea of God, maximal perfection is the reason of knowing that this idea also includes existence, and that this only happens in the ideal order. They also agree that this does not constitute the reason of being, that is, the reason why God exists. Therefore, the existence of God cannot be proved by a reasoning that moves from the idea of maximal perfection to necessary existence. However, Kant takes the consequences of this principle far beyond his predecessor. Crusius, on the one hand, thought that this critique would just disprove the ontological argument and, at the same time, strengthen the a posteriori demonstrations. Kant, on the other hand, finds in those demonstrations the same principle expressed in the ontological argument, according to which, maximal perfection is the reason of necessary existence.36 Crusius accepts this principle, but only in the ideal order, and not as a demonstration of the existence of God. He also accepts that, once the existence of God has been proved, this principle can be used to show that, in reality, the most perfect being has existence in its essence. Based on this analysis, the main contribution of this work to the ongoing debate on Kant´s indebtedness to his predecessors is to pose the following: It is possible that Kant thought that if this principle – namely, the one that allows the reasoning from maximal perfection to necessary existence –, holds even in the ideal order, it could still be used to prove that, in reality, there is a maximal perfect being that has existence in his essence. It is possible that, in rejecting this way of reasoning, Kant ended up stating that the principle according to which nothing has the reason of its existence in its essence holds not only in the ontological order, but also in the logical one.37 In fact, Kant did this shortly after when he denied that existence is a perfection or a predicate. Therefore, while Crusius will still hold the idea that God exists necessarily because existence is in his essence, Kant will deny it. And this is why, while Crusius will still hold the possibility of a demonstration of the existence of God (by a posteriori arguments), Kant will also deny this possibility in his mature works.
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Nikkarla, M. (2020), “Grounds of Existence in Kant’s New Elucidation”, International Journal of Philosophy 11, 250-271.
Perin, A., (2015), “The Proof of the Principle of Sufficient Reason: Wolff, Crusius and the Early Kant on the Search for a Foundation of Metaphysics”. Revista Portuguesa de Filosofia T. 71, Fasc. 2/3, Metaphysics: Historical Perspectives and its Actors, 515-529.
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Sassen, B. (2014), “18th Century German Philosophy Prior to Kant”. En The Stanford Encyclopedia of Philosophy. Ed. E. Zalta. http://plato.stanford.edu/archives/fall2014/entries/18thGerman-preKant/>.
Schönfeld, M. (2000), The philosophy of the young Kant. Oxford: Oxford University Press.
Spoerhase, C. (2010), “A case against skepticism: On Christian August Crusius logic of hermeneutical probability”, History of European Ideas 36. 251-259.
Watkins, E. (2005), Kant and the Metaphysics of Causality. Cambridge: : Cambridge University Press.
1 The expressions and meanings of the names ‘Thomistic objection’ and ‘Empiristic objection’ are taken from Harrelson, K. J., The Ontological argument from Descartes to Hegel, 159 and 172. It is also important to point out that the so-called ‘Thomistic objection’ is not the only objection that Saint Thomas Aquinas raised against the ontological argument, nor perhaps the most decisive one for him.
2 References to this work will be made by the paragraph number and the abbreviation E. All translations were made by Alejandro Vigo and me.
3 I decided to translate ratio as reason in a more literal way, although in this context the meaning may be closer to ground.
4 Kanzian’s paper is an analysis of Crusius’ influence in Kant’s writings from 1762/63.
5 Boehm proposes that Kant’s rejection of ‘existence’ as a predicate is the key element of the mature Kantian opposition to any metaphysical thought based on the ‘principle of reason’.
6 Perin analyses the strife between Wolff, Crusius and Kant about the foundation of metaphysics.
7 Longuenesse compares Kant’s pre-critical and critical view on the ‘principle of reason’.
8 Hogan (2009) discusses the ‘principle of reason’ in relation to the Aesthetic’s argument for the Subjectivity Thesis. Nikkarla (2020) analyses the meaning of ‘God’ as the ‘reason’ or ‘ground’ for the existence of everything. Watkins (2003) studies the ‘principle of reason’ as regards to early Kant’s natural philosophy. There is also Lu-Adler’s (2021) investigation about the role of the ‘principle of reason’ in Kant’s arguments for the possibility of two branches of theoretical philosophy.
9 Heimsoeth is one of the firsts to point out the importance of Crusius’ metaphysical thought in order to understand Kant’s critical turn correctly.
10 See, for example Sassen (2014).
11 Harrelson briefly enumerates some of the main ideas of this opposition: “In his chief metaphysical work, Sketch of the Necessary Truth of Reason (1745), he achieves a number of breaks with the German rationalist tradition that Kant will soon make more familiar: he distinguishes formal from real possibility; he rejects determinism; he defines existence with reference to space-time; he argues for a theology based largely on morality; most importantly, he rejects the derivation of the principle of sufficient reason from the principle of contradiction” (Harrelson, 2009, 160).
12 Hogan agrees that, according to Crusius, in order to preserve freedom, the Leibnizian-Wolffian epistemology based on the universality of the ‘principle of reason’ must be reformed. “For Crusius, then, the metaphysical conditions of freedom rule out a construal of the PSR as an unrestricted law. Since Wolff’s epistemology of rational knowledge relies essentially on such a construal, this epistemology must be rejected out of hand” (Hogan, 2009, 365). For a very complete description of Crusius’ rejection of dogmatic rationalism, see: Heimsoeth, 1926, 4-15.
13 It would be useful to point out that sometimes Crusius is very accurate about what he attributes to Leibniz and what to Wolff. For instance, his Dissertatio philosophica de usu et limitibus principii rationis determinantis vulgo sufficientis (Crusius, 1987), usually known as De usu he criticizes Wolff for trying to derive the truth of the principle of sufficient reason from the principle of contradiction but points out that Leibniz did not make this attempt (§11 y §14 DU). However, he refers to both Leibniz and Wolff when he says that the principle should be called ‘principle of determining reason’ and that it should be restricted because it introduces determinism (§1 - §5 DU). References to De usu will be made by the paragraph number and the abbreviation DU. All translations from this work were made by Agustín Echavarría and me.
14 Crusius explains the idea of free will as a first cause in §25 DU. I will not explain this relationship more deeply in order to avoid diverging too much for the main topic of this article.
15 In this analysis, I mainly agree with Longuenesse’s description (Longuenesse, 2001, 70-76).
16 All translations of this work will be taken from Kant, 2003. References will be made by the proposition number and the abbreviation ND. For some good analysis of the ‘principle of reason’ in Kant’s mature works see: Lu-Adler, 2021, 1–13.
17 Kanzian notices that, even though Kant shares some ideas with Crusius, it is not accurate to say that he is ‘crusian’ at this time: “Die naheliegendste Folgerung besteht somit darin, Kant 1763 keinesfalls als ‘Crusianer’ zu bezeichnen. Der ideengeschichtliche Zusammenhang der Schriften besagter Schaffensperiode muß angesichts der Tatsache, daß sich auch gegenüber der rationalistischen Schulphilosophie ihrer Zeit wesentliche Abweichungen, die vor allem die ersten beiden hier behandelten Themen betreffen, namhaft machen lassen, differenziert betrachtet werden, will man einseitigen Urteilen entgehen” (Kanzian, 2009, 405).
18 Schönfeld also agrees that in Nova dilucidatio Kant uses the same terminology than Crusius, but with a different meaning: “Kant´s terminology in the New Elucidation reveals Crusius´s influence. But in contrast to the earlier distinction between logico-epistemic and ontological aspects of causality, Kant´s employment of these terms had little to do with how Crusius´s defined them. Whereas Crusius referred with ‘determining reason’ to physical process and with ‘sufficient reason’ to freedom, Kant used ‘determining reason’ as a label for the principle of causality, which applies to both free and deterministic events, and ‘sufficient reason’ as a label for the conception of causality proposed by Leibnizian-Wolffian School” (Schönfeld, 2000, 147).
19 Crusius also makes distinction between these two concepts. However, they do not belong to the distinction between ‘reason of being’ and ‘reason of knowing’ but to the distinction between the a priori y a posteriori demonstrations that Crusius explains in §33 DU.
20 According to Perin, Kant justifies the principle of sufficient reason in “two progressive steps: (i) the establishment of a transmutability or logical equivalence of the principle of contradiction and the so formulated “principle of determining, commonly called sufficient reason”; and (ii) the assurance that the latter principle, as long as specified as a principle of “antecedently determining reason”, is the reason of being or becoming to be [ration essendi vel fiendi] of what exists in a contingent way” (Perin, 2015, 523).
21 Longuenesse does a very clever analysis arguing that Kant jumped “too quickly from distinguishing between reason that and reason why to asserting that there is always a reason why” (Longuenesse 2001, 67-87).
22 Even when he speaks about different kinds of actions (constant and contingent) in §24 DU.
23 Nikkarla points out that, as regards to the difference between ‘ground’ and ‘determination’, Kant is closer to Leibniz and Wolff than to Crusius. “For Kant, a ground is that which determines, whereas Crusius thinks that a ground need not determine to be sufficient. According to Crusius, a free agent, whether it be God or a created rational soul, is a sufficient ground for its actions, even though in free action the effect does not have a determining ground. It is true, according to this view, that everything has a sufficient ground, but it is not true that everything necessarily has a determining ground. While respecting Crusius’ distinction between sufficiency of a ground and determination, Kant sides with Wolff and Leibniz on the question of free action” (Nikkarla, 2020, 258-259).
24 For a deep analysis of Leibniz, Crusius and the pre-critical Kant concept of free action see: Forman, 2013, 323-334.
25 It is possible that the fact that Crusius had included this argument in his Ontology, rather than in his Natural Theology, is what inspired Kant to call it “Ontological argument” (Harrelson, 2009, 160).
26 Heimsoeth sees in this objection made by Crusius one of the main breaks with dogmatic rationalism and an important antecedent of Kantian thought. “Zwar wird der sogenannte ontologische Beweis, der immer schon seit seiner ersten Aufstellung den krassesten Ausdruck eines Begriffsrationalisnrns darstellte, bestritten. Der Anspruch, die Existenz Gottes ‘völlig nach geometrischer Manier, nemlich durch den bloßen Satz vom Widerspruche’ zu erweisen, muß abgewiesen werden! Von der in einem Begriffe des Verstandes eingeschlossenen Existenz […]. Das ist schon ein bedeutsamer Schritt vom klassischen Rationalismus weg in der Richtung auf Kant” (Heimsoeth, 1926, 26-27).
27 This objection against Leibniz and Wolff version of the ontological argument is very similar to the one made by Johannes Kater against Descartes formulation of Anselm’s argument (Descartes, 2008, 203).
28 The idea that once God’s existence has been proved, then we can attribute to him necessary existence because he is the most perfect being has already been stated by Saint Thomas Aquinas. “[…] Anselm’s reasoning must be understood in the following way. Once we understand God, it cannot be thought what God is, and (at the same time) that he does not exists. However, it does not follow from this that someone cannot deny or think that God does not exist. Because he can still think that there is not something greater than which nothing can be thought. That is why his reasoning proceeds from a supposition, that there is something greater than which nothing can be thought” (Saint Thomas Aquinas, 1956, lib. 1 d. 3, q. 1, a. 2, ad. 4). The translation is mine.
29 Here Crusius rejects the use of the ‘principle of contradiction’ and the ‘principle of reason’ to demonstrate the existence of God. However, he uses other tow principles that allow him to prove that if God exists, then he necessarily exists. These are the ‘principle of the inseparable’ (that what cannot be thought as separate cannot exist separately) and the ‘principle of the non-unifiable (that what cannot be thought as united cannot be connected) (E §15).
30 Beyond his critiques to rational theology of a speculative nature, Kant maintains the canonical formulation of the problem of the existence of God, which he treats under that rubric not only in the pre-critical period, as it can be seen in his texts examined in this paper, but also in his works of the critical period (see: Kant, 1990, A 583-681 / B 611-658).
31 “The argument for the existence of God taken from the concept of God was first discovered and stated, so far as I know, by Anselm, archbishop of Canterbury, in his book Contra insipientem, which still exists. […] These arguments are valid, if only it is granted that a most perfect being or a necessary being is possible and implies no contradiction or, what amounts to the same thing, that an essence is possible from which existence follows”. (Leibniz, 1976, 386).
32 One example of this choice is Findlay’s ontological argument for the non-existence of God. This argument is based on the idea that the concept of a being that has existence in his essence is a contradictory or impossible concept: “For if God is to satisfy religious claims and needs, He must be a being in every way inescapable, One Whose existence and Whose possessions of certain excellences we cannot possibly conceive away. And modern views make it self-evident absurd (if they don’t make it ungrammatical) to speak of such a Being and attribute existence to Him. It was indeed an ill day for Anselm when he hit upon his famous proof. For on that day he not only laid bare something that is of the essence of an adequate religious object, but also something that entails its necessary non-existence” (Findlay, 1948, 182).
33 This inference made by Crusius, based on the ‘principle of the inseparable’, could be considered a good example of the remaining possibility of a priori knowledge in his philosophy. Possibility that Kant will completely rule out later on, as Hogan points out. “Crusius nevertheless remains committed to the possibility of substantive a priori knowledge of reality incompatible with Kant’s mature philosophy. He develops his own distinctive and highly dogmatic epistemology as an alternative foundation for such knowledge. It is based on two highest “material” principles of knowledge, supposedly placed in our minds by God, which supplement the “merely formal” Principle of Contradiction. A Principle of Inseparability asserts that what cannot be thought of as separate cannot exist separately; and a Principle of Non-Combinability that what cannot be thought of as connected cannot be connected” (Hogan, 2009, 365).
34 “Existence is not an attribute” (Kant, 1900, 2:156). The translation is mine.
35 Boehm thinks that the whole Kantian critical philosophy is based on the idea that existence is not a predicate: “The attack on the ontological argument is presented within the context of the criticism of reason, not as an indispensable assumption of that criticism. As we now see, however, Kant’s rejection of the supreme principle of pure reason, the PSR, depends on the claim that existence is not a predicate. For the claim that we cannot have legitimate knowledge of the ‘obviously synthetic’ supreme principle depends on the claim that existence is not a predicate. In fact, the Kantian project more generally depends on the same assumption” (Boehm, 2016, 566).
36 According to Heimsoeth, Kant would think that Crusius’ demonstrations of the existence of God are still dogmatic. “Gottesbegriff. Ausführliche Beweise (‘demonstrativische’ und WahrscheinlichkeitsBeweise) von der Wirklichkeit des Gottes, von seinem Wesen und seinen Eigenschaften bilden das Kernstück von Crusius’ Metaphysik; eine vollkommen gewisse und zuverlässige Erkenntnis von der ‘schlechterdings nothwendigen und ewigen Substanz’ ist unserm Verstande möglich, und von der theoretischen natürlichen Theologie zu leisten. Insofern also bietet diese Metaphysik, von Kants Kritik der Gottesbeweise aus gesehen, durchaus das Bild des ‘Dogmatismus’” (Heimsoeth, 1926, 26).
37 This hypothesis is aligned with the following conclusion by Boehm. “The traditional ontological argument is assumed, albeit implicitly, in the assumption that the PSR is true. Every attempt to justify that principle would amount to justifying the claim that existence is a predicate. Therefore, whoever finds Kant’s refutation of the ontological argument conclusive has a good reason to reject Spinoza’s alternative PSR-arguments for the existence of God” (Boehm, 2016, 565-566).