Unity in Reason: Mendelssohn on the Conflict between Common Sense and Speculation

Abstract

The paper aims to clarify Mendelssohn’s stance on speculative philosophy by connecting the conflict between common sense and speculation with the notion of approval-drive. It argues that Mendelssohn identifies a principle of existence in the faculty of approval, aligning common sense with the divine nature, thereby challenging the skepticism inherent in metaphysical speculation. By invoking God’s creative impetus, Mendelssohn demonstrates that the ontologically abundant world conceived by common sense is more consistent with the divine nature than the ontologically impoverished worlds envisioned by metaphysicians. This approach positions Mendelssohn within the tradition of Descartes, Spinoza and Leibniz, emphasizing the role of the divine intellect as the guarantee of the accord between perceived and actual reality.

1. Introduction

Although focused on a single theme—the proofs of God’s existence—Mendelssohn’s Morning Hours serves multiple agendas.1 Written during the so-called “Pantheism controversy,” one of its primary objectives is to refute Spinozism. However, Mendelssohn also pursues other goals in this work. He seeks to rehabilitate Lessing against Jacobi and attempts to engage with the emerging philosophy of Kant.2 More broadly, the work aims to present Mendelssohn’s philosophical testament and honor the school of thought in which he was educated. These various strands do not necessarily form a unified whole. One issue that continues to puzzle interpreters is Mendelssohn’s actual stance towards the speculative philosophy he claims to defend. In the preface, he expresses his intention to rehabilitate the Leibniz–Wolff school of thought. However, he also voices serious reservations towards speculative metaphysics. At times, the reader may get the impression that the actual adversary of the work is speculation itself and that Morning Hours was written to counter the pernicious effects of unrestrained metaphysical rumination.

The following reflections aim to shed light on this issue by connecting two seemingly unrelated themes in Morning Hours: the conflict between common sense and speculation, and the notion of approval-drive. Mendelssohn famously considers common sense and speculative reason as two facets of the same faculty but favors common reason in cases of conflict between the two. This preference for common sense over speculation has raised suspicions about Mendelssohn’s genuine commitment to reason, leading some scholars to interpret his stance as a form of disguised fideism. This paper proposes a different interpretation of this conflict. I argue that the conflict revolves around the fact that common sense unproblematically posits realities beyond the self—such as bodies and other minds—which speculation views as problematic and dubious. Whereas common sense tends toward realism, speculation is “de-realizing” and leans toward skepticism. Mendelssohn perceives this disagreement as a deficiency on the part of metaphysical speculation, which lacks a principle of existence to account for realities beyond the self. Mendelssohn identifies this principle with the faculty of approval or approval-drive (Billigungsvermögen; Billigungstrieb), a concept rooted in aesthetics. At the human level, this faculty explains the mind’s tendency to fictionalize and create aesthetic works; when applied to God, it accounts for the creation of a universe with a maximum of beings and relationships. My claim is that Mendelssohn invokes God’s creative impetus to demonstrate that the world as conceived by common sense—a world that is ontologically abundant—is more consistent with God’s nature and properties than the unreal and ontologically impoverished worlds envisioned by metaphysicians. Thus, Mendelssohn resorts to speculation to defend common sense against what he perceives as deceptive and sophistical speculation. The picture of Mendelssohn that emerges from these reflections is that of a thinker less skeptical of speculation than is sometimes portrayed. In resolving epistemological problems by involving the divine nature, Mendelssohn aligns with the school of thought of Descartes, Spinoza, Leibniz, and others, for whom God is the mediator between reality as we perceive it from our partial perspective (quoad nos) and reality as it is in itself (quoad se).

To substantiate these claims, I will proceed as follows. In the next section, I examine Mendelssohn’s notion of common sense and propose a reinterpretation of its conflict with speculation. In Section 3, I elucidate Mendelssohn’s conception of the task of philosophy as the translation of the dicta of common sense into clear concepts. In Section 4, I demonstrate how the notion of approval-drive provides the principle of existence, the absence of which renders metaphysical speculation hostile to common sense, and show how its application to God reconciles common sense with speculation.

2. Common Sense and Wakefulness

Common sense, its role in human knowledge, and its relationship to speculative reason are recurring themes in Mendelssohn’s oeuvre from the beginning.3 This topic receives its most detailed consideration in Morning Hours, thus constituting one of its guiding threads. Common sense is also a subject of great interest in the 18th century. According to Amos Funkenstein, this interest is linked to the Enlightenment ideal of education as egalitarian and accessible to everyone (Funkenstein 1986, p. 359). Its importance may also be linked, as the following reflections will show, to the overall decline of metaphysics in Mendelssohn’s time and the quest for an alternative to argumentative reason as a means of cognitive access to reality.

In conformity with the term’s use among his contemporaries, Mendelssohn understands common sense primarily as “a source and faculty of primary insights […], which provides truth without the help of explicit arguments of the understanding and reasonings” (Maydell and Wiehl 1974, p. 244). Thus characterized, common sense functions as an “organ of truth” or “sense of reality” within us. Given its ability to apprehend reality without explicit arguments, common sense stands in contrast to reason, which also serves as an “organ of truth” but operates through arguments and chains of demonstrations. However, as the term “explicit” implies, reasoning is not absent from common sense: its operations are also inferential, albeit in a tacit or implicit manner—one might even say “unconscious” (Mendelssohn 1971, JubA 3.2, p. 33).4 The distinction between common sense and reason thus lies in their speed and approach: they are fundamentally the same faculty, but while common sense operates swiftly and pre-theoretically, reason progresses step by step, carefully considering each new development (Mendelssohn 1971, JubA 3.2, pp. 33–34, 50).

Philosophy—understood as the quintessential inquisitive and conceptual discipline—should, according to Mendelssohn, be seen as a theoretical elucidation of the dicta (Aussprüche) of common sense (Mendelssohn 1971, JubA 3.2, p. 50).5 Philosophy thus renders explicit and conceptually precise what we already intuitively understand through common sense. Consider, for example, the difference between being awake and being asleep. To common understanding, this difference is obvious and self-evident. However, philosophy undertakes extensive conceptual labor to elucidate the distinction between the two states (Mendelssohn 1971, JubA 3.2, p. 50). Similarly, even the most uneducated mind assumes the existence of a deity who creates and governs the world. It is the role of philosophy to clarify and purify this vague intuition, stripping it of prejudices and inaccuracies (Mendelssohn 1983, p. 95; 1971, JubA 3.2, pp. 197–98). The same applies to the belief in the immortality of the soul (see Freudenthal 2012, p. 30). Hence, common sense is not limited to basic elements of reality but also encompasses ultimate truths about the world. Philosophy, as Weltweisheit, is a refined version of the worldly wisdom that constitutes common sense and through which we get our bearings in reality.

The genetic connaturality of philosophy and common sense does not preclude their disagreement. In fact, the opposite seems to be the case in Mendelssohn’s time. Frederick Beiser has vividly described the growing impression in late 18th century Germany that speculative reason, rather than confirming basic certainties such as God, freedom and morality, actually undermines them (Beiser 1987, pp. 1–3). This is the predicament behind the so-called Pantheismusstreit and the significant problem addressed in Morning Hours. The solution proposed by some, like Jacobi, is to abandon reason and embrace fideism. This is not Mendelssohn’s stance: by tracing common sense and philosophical reason back to the same source, Mendelssohn takes a clear position in the dispute against fideistic views such as Jacobi’s, advocating instead for reason. Mendelssohn has encapsulated his approach to this issue in a well-known formula:

Truthfully, this rule also tends to serve me as the right guide when I am awake. Whenever my speculation seems to lead me too far from the main street of common sense, I stand still and seek to orient myself. I look at the point from which I started out and try to compare my two guides. Experience has taught me that in most cases common sense tends to be right and reason must speak very decisively for speculation if I am to leave common sense and follow speculation […].

(Mendelssohn 1971, JubA 3.2, p. 82; 2011, pp. 59–60)6

This is the so-called “method of orientation” (Beiser 1987, p. 30): whenever speculation diverges too significantly from the path of common sense, we must endeavor to identify the point of their divergence and realign them. However, what should we do if their discrepancy seems irreconcilable? In such cases, as Mendelssohn suggests, common sense should be preferred, although this rule admits exceptions, as the text indicates.

In Jerusalem and An die Freunde Lessings, Mendelssohn illustrates this principle concerning religious belief, which he regards as part of common sense. He argues that even the most rudimentary and philosophically uninstructed individual can infer the existence of an invisible and all-governing deity from observing reality impartially (Mendelssohn 1983, p. 95; 1971, JubA 3.2, pp. 197–98). Even the most unrefined humanity “hears and sees […] the all-vivifying power of the Deity everywhere” (Mendelssohn 1983, p. 95). Although this conception may be philosophically unsatisfactory and open to further refinement, it is fundamentally true for Mendelssohn and provides a firm anchorage for the human mind. However, some thinkers, through subtle reasoning and highlighting the deficiencies of common sense, have denounced this belief as false and illusory.7 Mendelssohn acknowledges that this crude notion of the divine has its shortcomings (“This mode of conceiving things has in it something defective, […]”; Mendelssohn 1983, p. 95). Yet, these shortcomings do not diminish his conviction in its truth in the slightest, precisely because his belief is founded on a more fundamental and quasi-instinctive certainty rather than on intricate reasoning (Mendelssohn 1971, JubA 3.2, p. 197).8 Similarly, my certainty that I am awake and not asleep, as well as my certainty regarding the existence of a physical world beyond my representations, is basic and does not rely on complex argumentations. The strength of common-sense certainties over the artificial and contrived arguments of metaphysical speculation seems to lie in their pristine and pure-minded character.9

Clearly, this rule is far from straightforward and has generated considerable perplexity both among Mendelssohn’s contemporaries and modern scholars.10 Doubts naturally arise about the reasonableness of consistently favoring common sense—with its deficiencies and flaws—over the probing nature of inquisitive reason. Mendelssohn’s contemporary critic and Jacobi’s devotee Thomas Wizenmann (1759–1787) contended that Mendelssohn’s preference for common sense over speculative reason and Jacobi’s fideism are, despite their apparent antagonism, are ultimately “in perfect agreement” (vollkommen einig; Wizenmann 1786, p. 47). Strauss suggests that Mendelssohn gradually lost confidence in metaphysics and embraced common sense as a way to defend Judaism.11 Altmann’s position is more nuanced; he acknowledges that the proofs of God’s existence are not “the raison d’être of his faith,” asserting that the foundations of Mendelssohn’s conviction in ultimate metaphysical truths are not theoretical (Altmann 1982, p. 151). For Arkush, Mendelssohn’s concept of common sense is a “kind of faith […] unconvincingly disguised as reason” (Arkush 1994, p. 92). Beiser, while taking Mendelssohn’s adherence to reason seriously, views his defense of common sense as dangerously close to a form of “dogmatism” that is hostile to “all inquiry and criticism” (Beiser 1987, p. 102). Freudenthal rightly rejects the interpretation of the disagreement between reason and common sense in Mendelssohn as a conflict between reason and “another faculty, different in kind, or between reason and belief or faith” (Freudenthal 2012, p. 31). In his reading, Mendelssohn’s reliance on common sense arises from his empiricist inclinations, leading him to distrust metaphysics due to the “elusive nature of metaphysical objects” (Freudenthal 2012, p. 48). However, this view is difficult to reconcile with Mendelssohn’s inclusion of metaphysical truths among the certainties of common sense.

We align with Freudenthal in rejecting the interpretation of the conflict between common sense and speculation as the one between faith and reason. Instead, we offer the following interpretation: Mendelssohn portrays this disagreement as revolving around the fact that common sense accepts realities that speculation deems unwarranted. Insofar as it attributes objectivity and substantiality to certain among our perceptions, common sense is “realistic”, whereas metaphysical speculation tends to be “idealistic” and “skeptical”.12 Mendelssohn’s argues that this disparity is not merely because common sense is credulous and naïve but because it has the unique ability to transcend our limited perspective and perceive things as they truly are, irrespective of our subjective viewpoint. Metaphysics often struggles to match this capacity, which is why common sense should be given precedence. To better understand this point, let us examine in greater detail how common sense operates and arrives at its insights according to Mendelssohn. As the term suggests, common sense seeks what is common. Yet common to what? Before its shift in meaning in the seventeenth century, common sense in scholastic terminology referred to “the underlying capacity to coordinate the data that flow to the mind from the five sense organs; without it, we could not identify a common source to given perceptions” (Funkenstein 1986, p. 359). Expanding the meaning of the term—as Mendelssohn does—common sense grasps what is common to various perceptions of the same perceiver and even to the differing perceptions of multiple perceivers. The common element in this plurality, the sameness within difference, is then taken as an indicator of a unitary and common reality beyond the diversity of our subjective perceptions, which causes the agreement (Übereinstimmung) among them (Mendelssohn 1971, JubA 3.2, pp. 15, 19).13 By discerning what is common, common sense transcends our limited perspective and provides cognitive access to an external world.

Mendelssohn calls “wakefulness” (das Wachen) the mental state in which common sense—understood as the perception of the one common reality—is effective and prevails over other dispositions, such as sleep, rapture, drunkenness, etc. (Mendelssohn 1971, JubA 3.2, pp. 45–47). Being awake is, for Mendelssohn, the “consciousness of the present” that enables our mind to apprehend reality as it is in itself, regardless of our particular viewpoint, mood swings and cognitive shortcomings. By virtue of this capacity—common to all rational beings—reality appears to us as a unitary and coherent whole. Sleep, by contrast, is the retreat of the mind from objective reality into a purely subjective realm, whose structure is at variance with the common order of nature. In this respect, sleep—along with related states such as dreaming, drunkenness, madness, and rapture—should be counted among the weaknesses and limitations of the mind, whereas wakefulness represents the mind’s power to transcend itself (Mendelssohn 1971, JubA 3.2, p. 51). We can now better understand why Mendelssohn counts religious belief among the insights of common sense. The notion of an ultimate and common source of all things, endowed with supreme intelligence and governing everything, aligns with the logic of common sense, which discerns the unifying principles of reality. Thus, the idea of God epitomizes the height of intellectual wakefulness; it is the pinnacle of common sense.

In support of this equation between common sense and wakefulness, Mendelssohn quotes Heraclitus,14 who is credited for having stated “that the world of the waking is one and shared but that the sleeping turn aside each into his private world.”15 According to the Heraclitus expert Charles H. Kahn, “the waking” are those among human beings that grasp the general structure of reality as well as the cosmic principle that governs it. In this respect, being awake is tantamount to reason, judgment and good sense (Kahn 1979, p. 102). “The sleeping”, by contrast, are those among human beings—for Heraclitus, the majority of them (Kahn 1979, p. 115)—who fail to apprehend the cosmic order and therefore remain imprisoned in their own particular world. Taken in this sense, “sleep” is equivalent to “cognitive alienation” and “epistemic isolation” (Kahn 1979, pp. 100–1). By virtue of reason, the waking inhabit a unified and common world, while the world of the sleeping is irreducibly plural and fragmentary. Unsurprisingly, Mendelssohn recognized in Heraclitus’ saying a great affinity with his own thought.16

We can now better appreciate the tension between common sense and speculation. Their disagreement hinges on the extent of our wakefulness and sense of reality. From the perspective of speculation—and for reasons that will be further explored in the next section—a substantial portion of what common sense regards as real and certain is actually a product of our cognitive limitation; it is sleep rather than wakefulness. For the idealist, the objective world consists only of minds, and the commonsensical belief in a physical world is a mere prejudice. For the Spinozist, there is no objectivity outside of God, while for the skeptic, there is no objectivity at all. All these positions share a “de-realizing” quality: by challenging truths that common sense takes for granted, they evoke a sense of estrangement from reality, leading to what Mendelssohn calls “disorientation”. The crux of the matter is that they pursue this in the name of wakefulness and rational vigilance. Mendelssohn’s insight, as I interpret it, is that unrestrained philosophical vigilance, left to itself, can become a malady of the soul, akin to delirium or madness: it detaches the mind from the one common reality, producing the very opposite of its intended effect, i.e., cognitive alienation and epistemic isolation.17 Speculation often mistakes the inadequacies of common sense—which Mendelssohn acknowledges—for complete errors, thus missing the essential truths they contain. Instead of refining our rough certainties by discerning the adequate from the inadequate within them, speculation persistently dismisses them as mere prejudices, thereby undermining our very sense of reality.18 The issue with speculation is thus its one-sidedness: in its fight against prejudice (=sleep), it fails to recognize the truth embedded within ingrained beliefs, a truth that ultimately results from a power in us.

The conclusion to draw is as follows: philosophy, according to Mendelssohn, should enhance our sense of reality, not impair it. It should orient us, not lead to disorientation; it should grant cognitive access to a shared world—the world of the waking—rather than confine us in our particularity. Therefore, philosophy should refine common sense, infusing its dicta with the rigor they lack and supporting their claims to objectivity. The meticulousness of speculative reason should serve to bolster our sense of reality. But how exactly can this be achieved? We will explore this in greater detail in the next section.

3. Speculative Reason and the Step into Existence

Speculative reason, as already shown, must underpin the certainties of common sense by providing proofs and demonstrations for what common sense intuitively and unproblematically assumes. In this task, speculative reason encounters conundrums that common sense does not even suspect. What is unproblematic for common sense—such as the distinction between wakefulness and sleep—becomes a formidable problem for speculative reason. This explains why philosophical discussions are often perceived as “lächerlich” by laypeople (Mendelssohn 1971, JubA 3.2, p. 50). However, while Mendelssohn privileges common sense over speculative reason, he also acknowledges that the scruples and objections of the latter are serious and significant. Philosophy must contend with difficulties from which other disciplines—such as mathematics and physics—are exempt, significantly complicating its task. One particularly thorny issue is “the step into existence” (or “step into the realm of actuality”; Mendelssohn 1997, p. 274), which, as we are about to show, is ultimately responsible for the disagreement between common sense and speculation. According to Mendelssohn, this issue can only be resolved by resorting to the divine nature and its attributes.

As Mendelssohn notes in his Prize Essay, several factors significantly complicate the task of philosophy compared to mathematics. To begin with, philosophy uses common language rather than an artificial one, necessitating an endless clarification of the terms it employs (Mendelssohn 1997, pp. 272–73). Furthermore, philosophy deals with qualities rather than quantities, which are so intricately interwoven that defining one requires defining all the others (Mendelssohn 1997, p. 273). However, the greatest challenge lies in the fact that philosophy—unlike other disciplines—cannot simply take for granted the reality of its objects; it must demonstrate their existence. For instance, when examining the relationship between the mental and the corporeal, philosophy cannot merely define and distinguish them; it must also prove their reality (or unreality). This step, “the transition from concepts to actualities” (Mendelssohn 1997, p. 275), is the most difficult one, where the skeptic lurks with his doubts and scruples (Mendelssohn 1971, JubA 3.2, p. 43). While the existence of my perceptions qua perceptions, as well as my own existence as their perceiver, is beyond doubt—even the most stubborn skeptic must admit this—great difficulties arise when I try to move beyond my subjective sphere and establish the existence of realities independent of it. The clear certainty of the cogito then disappears. For, who can assure me that what I perceive as external and independent of my perception is not, in reality, an illusion born of my cognitive limitation?

This issue is central to the various positions in metaphysical speculation and explains their diversity. The idealist concedes the reality of other minds but not the existence of bodies; the Spinozist denies the independent reality of the human mind outside of God, making us thoughts of God; and the solipsist, opposing both, accepts the extra-divine substantiality of the human mind but denies the reality of other minds. In contrast to these positions, common sense is generous in admitting realities beyond the self: my immediate “sense of reality” assures me of the existence of other minds, a physical world independent of my perceptions, and a divinity that produces these realities and grants them extra-divine substantiality. Therefore, if philosophy is to uphold the certainties of common sense, it must address the problem of “the step into existence” and find a principle of ontological abundance that is conspicuously absent in metaphysical speculation.

We know already how common sense approaches this issue, namely through consensus and agreement (Übereinstimmung) between different perceptions and perceivers: “The more, however, that fellow human beings agree with me in finding these things to be so, the greater becomes the certainty that the ground of my belief is not to be found in my particular situation” (Mendelssohn 1971, JubA 3.2, p. 54; 2011, p. 38). Yet this method cannot entirely satisfy speculative reason. Partial perspectives taken together only amount to a wider partial perspective, a limited perspective of broader scope: all the same, we are still imprisoned in partiality.19 The only way in which consensus and agreement can achieve complete certainty about reality as it is in itself is by finding consensus, not among finite perspectives but between my finite perspective and the all-encompassing perspective of an infinite and unrestricted intellect, i.e., God:

If we could be persuaded that the supreme intellect exhibited to itself the things outside of us as actual objects, then our assurance of their existence would have attained the highest degree of evidence and there would be no further increase that it might undergo […] If we shall have convinced ourselves of the existence of the supreme being and its properties, then a way will also present itself of making for ourselves some concept of the infinity of the supreme being’s knowledge and from this truth, along with several others, perhaps in a scientific, demonstrative manner, of refuting the pretensions of the idealists and of proving irrefutably the actual existence of a sensory world outside us.

(Mendelssohn 1971, JubA 3.2, p. 55; 2011, p. 38)

An infinite intellect comprehends reality without any limitations or distortions, perceiving it as it truly is. Such an intellect is pure activity, an unconstrained Denkungskraft, and truth is every knowledge grounded in the power of the mind (with error being a limitation thereof; see Mendelssohn 1971, JubA 3.2, p. 34). Demonstrating that the perspective of such an intellect aligns, at least in some respects, with ours would perfectly validate our view of things. This would elevate the probable certainty of common sense to total, apodictic certainty.

Before examining how Mendelssohn demonstrates this point, it is necessary to clarify some ambiguities in the quoted passage, particularly the phrase “the supreme intellect exhibits to itself the things outside of us as actual objects.” At first glance, this statement appears inaccurate because, unlike us, God does not find things ready-made but rather produces them. Consequently, His relationship with external reality cannot be the same as ours: God cannot “exhibit to Himself” things outside of us as if they were ontologically independent and self-sufficient with respect to Him, for the physical realm has its source in God and therefore depends on Him. The following phrase gives us the key: “the things outside of us as actual”. Mendelssohn’s demonstration does not aim to show that God perceives the sensory world as we do—namely, as an external reality independent of His perception—but rather that this sensory world is also actual for God, meaning that it possesses its own substantiality outside of God, even if God has created it ex nihilo and thus is not strictly speaking external to Him. Against idealists and Spinozists, it must be demonstrated that the physical world possesses an actual, extra-divine existence. Therefore, it must be shown that God posits something outside of Himself, exteriorizing His essence and manifesting His power through realities endowed with ontological self-sufficiency.

Yet, how is this to be convincingly demonstrated? As the text suggests, we must first examine the properties of the supreme being and form a concept of its infinite knowledge. Based on this concept, we must then show that it is inherent to the Deity not to remain absorbed in itself, but to create, to produce something outside of itself. Mendelssohn is thus inviting us to explore something akin to a “logic of divine creation.” Before delving into the specifics of this highly speculative inquiry, it is crucial to note how the terms of the problem have shifted: we have transitioned from an epistemological question—concerning the nature and scope of common sense—to a theological one, focused on the internal constitution of the divine nature and its intrinsic property to create.20 The validity of common sense is thus demonstrated through an analysis of the divine intellect, an approach that connects Mendelssohn not only with Wolff and Baumgarten but also with the philosophical tradition of Descartes, Spinoza, and Leibniz.21

4. Approval-Drive and Logic of Creation

In Chapter 12 of Morning Hours—and on the basis of the conceptual distinctions introduced in Chapter 7—Mendelssohn sets out to demonstrate that the supreme intellect is creative and that it creates the world in a manner consistent with common sense. To achieve this, it is insufficient to merely examine the nature of the supreme intellect as unrestricted knowledge or unlimited understanding. Indeed, an unlimited understanding encompasses everything that is conceivable without contradiction, comprehending the entire sphere of being as opposed to non-being, which is unthinkable or absurd. Taken in this sense, the supreme intellect cannot give us the key to the actually existing world—i.e., the world as conceived by common sense—for this world is as conceivable as those envisioned by the idealist or the solipsist. Put differently: the ultimate reason for the existence of the world of common sense cannot be its mere thinkability or its being the object of an unlimited understanding, as alternative worldviews are equally conceivable without contradiction. They equally fall within the divine understanding as possible candidates for existence.

It is therefore necessary to consider the divine intellect from another perspective, not merely as a perfect faculty of knowing. We must assume that a different faculty or power operates in the divine intellect, which—unlike mere knowledge—does not have being as such or conceivable reality as its object, but rather certain thinkable realities to the exclusion of others. This faculty, in contrast to mere knowledge, discriminates within the realm of being, not between true and false (since everything thinkable is true) but between what is preferable and what is not, between what is worthy of existence and what is not (keeping in mind that what cannot absolutely exist is unthinkable). Mendelssohn refers to this power as the “faculty of approval”, and its focus is on what is preferable or desirable, as opposed to what is not (Mendelssohn 1971, JubA 3.2, p. 62). Unlike the one between being (thinkable) and non-being (unthinkable), this distinction is not absolute but admits of degrees, “pluses and minuses”; certain things are preferable under specific circumstances and not under others. In any case, if we acknowledge such a faculty within the divine intellect, we might be able to explain the existence of the world of common sense as a world that is preferable and more worthy of existence than the equally conceivable worlds of idealism and solipsism. Thus, we can hypothesize that the realities assumed by common sense and denied by speculative metaphysics—such as physical bodies and a world outside of God—ultimately exist because a faculty of approval in God has endorsed their transition to existence.22

There is another compelling reason to support this hypothesis. When we examine the human mind, we notice that knowledge and approval—truth-drive and approval-drive—exhibit, so to speak, opposite directionalities. Although they are “expressions of one and the same power of the soul […] they differ with regard to the goal of their striving” (Mendelssohn 1971, JubA 3.2, pp. 63–64; 2011, p. 44). In the case of the truth-drive, the mind seeks to understand the nature of things and aims to align its concepts with reality, irrespective of the approval or disapproval these realities might evoke. For example, if I investigate a specific event, such as the murder of a loved one, I will strive to uncover all the details and align my understanding with the objective truth, regardless of whether I find it agreeable or not. In this scenario, it is about adjusting our mind to reality, not the reverse. Thus (and this is the crucial point), the directionality of the truth impulse flows from things or objective reality to the mind: it begins with how reality is constituted and shapes the mind accordingly (Mendelssohn 1971, JubA 3.2, p. 64).

The case of approval-drive is different. Here, the aim is not to align the mind with the objective reality of things but to adjust or conform things to the mind, according to its concepts of the good, the desirable, and so forth. The impulse of approval seeks to modify reality, perfecting it according to its inclinations and molding it according to the self. This gives rise to the human tendency toward fiction and fabulation: “He reshapes things as they suit his inclination and as they set satisfaction and dissatisfaction into an agreeable play” (Mendelssohn 1971, JubA 3.2, p. 65; 2011, p. 45). Thus, the movement starts from the mind and extends outward toward things; external reality is shaped according to the mind. The impulse of approval is thus a movement ad extra, outward of oneself; a poietic impulse, one of exteriorization and creation.

If we assume that God possesses an approval-drive in addition to a truth-drive intrinsic to His nature as an infinite intellect, we can then explain how God, rather than remaining absorbed in Himself, exteriorizes Himself and produces beings outside of Himself. Just as the approval-drive in humans leads to the creation of fictions and fables, when applied to God, it results in the production of an extra-divine reality—i.e., a world. Since the approval-drive entails notions of the beautiful and the good, accompanied by a poietic impulse to realize them externally, the divine approval-drive must manifest itself in the creation of the most preferable and approvable world among all conceivable worlds. The actually existing world is thus a world produced and molded according to God’s nature, an artistic work embodying divine aesthetics:

The aim of the power of approving is to bring forth the object, to strive to bring the object of the representation to actuality, in keeping with the standard of the ideal. The power of the self-sufficient being will thus bring forth these limited degrees of its perfection and their best possible combination, not in himself since they are not compatible with his properties but outside himself as limited substances, subsisting for themselves, each with that alteration in place and space, by means of which they are the best in relation to the whole. God is the creator and sustainer of the best universe. One sees here the transition from God’s intellect to his property as creator and sustainer of things outside him. Representation, combined with approval or participation, is vital knowledge and vital knowledge in the highest degree is the spur to activity, the striving to bring forth, to express power.

(Mendelssohn 1971, JubA 3.2, p. 102; 2011, pp. 73–74)

As the text indicates, the approval-drive facilitates the transition from the notion of God as an unlimited intellect to that of God as a creator. Knowledge combined with approval is no longer static or contemplative but becomes dynamic: “vital knowledge” (lebendige Erkenntnis). Given that the approval-drive discerns the best from the less good within the realm of truth, God’s vital knowledge must necessarily produce and sustain the best possible universe. Since nothing can surpass the perfection of divinity itself, the reality created by God must necessarily be inferior to the creator, as it is derivative and secondary (Mendelssohn 1971, JubA 3.2, pp. 101–2). Nevertheless, since the created world results from an act of divine approval, it must necessarily be the best conceivable universe. This implies a universe where the maximum variety is combined with the maximum unity.23 This condition is more adequately fulfilled by a world composed of both minds and bodies rather than by a world containing only minds, as in the idealist perspective. The existence of both bodies and minds not only increases the world’s ontological richness and variety24 but also enhances its connection, interrelation, and harmony:

The same combination of things in which the matter as an object of representation is actually on hand must be necessarily more perfect than one in which the [represented] sensory make-ups have externally no object. In the latter there is merely harmony in thinking beings’ representations insofar as they are depictions and contain truth; in the former, by contrast, the thinking beings’ representations agree not only among themselves but also with an object that is actually to be found outside them, an object that is the prototype for their pictorial representations. In the former case, depiction agrees only with depiction; in the latter, by contrast, copy also agrees with prototype. Greater agreement is greater perfection; a world in which matter is to be encountered outside minds is more perfect than one that consists merely of minds. Since then God brings only the most perfect to actuality, the world that he has created will not be merely ideal but will also actually contain matter, just as the greatest harmony demands.

(Mendelssohn 1971, JubA 3.2, p. 103; 2011, p. 74)

The greater the reality, the greater the ontological profusion, and the greater the harmony and concordance between its different parts and regions.25 In a world composed of both minds and bodies, there is concordance between minds and the material realm they perceive, as well as among the different minds that inhabit a shared world (the world of the awakened in Heraclitus’ words). Plurality of beings entails plurality of relationships, and in general greater relatedness within a comprehensive unity. Therefore, the ontologically rich world of common sense is more perfect and consistent with the divine approval-drive than the austere and parsimonious universes conceived by the idealist and the Spinozist, not to mention the skeptic.26

Thus, in the faculty of approval—common to both humans and God—we find the principle of existence that speculative metaphysics lacks, and whose absence leads metaphysicians to deny all those realities that common sense accepts without question. Our belief in the existence of a physical world beyond our perceptions and the existence of other minds is grounded not only in sensory testimony and common sense but also in a thoughtful consideration of the divine nature and the creative impulse that must necessarily be attributed to it. Therefore, the contradiction between common sense and metaphysical speculation is only apparent: a comprehensive understanding of the divine nature and its attributes provides metaphysical speculation with the conceptual resources—such as the notion of approval-drive—to harmonize with common sense.

5. Concluding Remarks

The preceding reflections have shown how the notion of approval-drive allows Mendelssohn to reconcile common sense with metaphysical speculation. When applied to the supreme intellect, this concept provides an account of God’s creative impetus and the governing principles behind it. From the perspective of divine creativity, profusion of beings and relations is preferable to their scarcity. Consequently, the world of common sense—characterized by its ontological abundance—is preferable to the impoverished worlds of idealism, Spinozism, and solipsism. Thus, the realities assumed by common sense, which idealists and Spinozists dismiss as unwarranted, receive their proper rational validation through metaphysical speculation. Simultaneously, we uncover the missing element in metaphysical speculation that rendered it hostile to common sense: a principle of existence, such as the approval-drive, that accounts for the actuality of realities whose non-existence is conceivable.

All of these speculations would be mere castles in the air if they were not accompanied by a conclusive proof of God’s existence. It is futile to demonstrate that common sense aligns more closely with the divine nature than idealism or Spinozism if the existence of the divine nature itself is not established. Successfully proving God’s existence would entail that a supreme intelligence, exercising its faculty of approval, has decreed the existence of a world containing the maximum number of beings and relationships—i.e., the world of common sense. Such a proof would provide the final resolution to disputes with idealism, Spinozism, solipsism, and similar perspectives.

This is what Mendelssohn sets out to do in Chapter 16 of Morning Hours, where he provides a “new proof for the existence of God on the basis of the incompleteness of self-knowledge”. Mendelssohn claims that no such proof has ever been devised before (Mendelssohn 1971, JubA 3.2, p. 141). Without delving into the details and intricacies of this proof, several key observations can be made. 27As already noted, the ultimate goal of the proof is to demonstrate the validity of common sense against opposing viewpoints such as idealism and Spinozism. Consequently, the proof must possess definitive characteristics. Specifically, it cannot presuppose or rely on any realities that speculative metaphysics questions—such as the existence of a physical realm, or other minds, etc.—as that would amount to assuming what needs to be proven. For instance, it cannot infer the existence of a first cause from the physical world, as such a proof would be unacceptable to idealists and solipsists from the very outset. The proof must therefore start from an absolutely indisputable truth accepted by all perspectives, regardless of their skepticism, to wit: the certainty of my own existence. From this foundational truth, it must ascend to the existence of God without any further assumptions. In doing so, the proof moves from the isolated realm of the self—the private world of the sleeping according to Heraclitus—to the shared and unitary reality of common sense—the common world of the waking.

Regardless of the success of this demonstration (and of others, like the ontological argument as formulated in Chapter 17)28, the mere attempt to undertake it reveals, for Mendelssohn, the boldness and audacity of the human mind. This effort signifies a consciousness that, despite its finitude and limitedness, the human mind can somehow grasp the infinite and ascend to the divine, thus revealing a certain connaturality between God and the human mind (Mendelssohn 1971, JubA 3.2, pp. 156–57). This clearly supports our wakefulness and sense of the real: while it is undeniably true that our apprehension of the world is limited and perspectival, we have the intellectual ability to transcend our particularity and, in some way, perceive things as God does. Both common sense and speculation attest to this extraordinary power of the human mind. For this reason, it is crucial for Mendelssohn to ensure their alignment and harmony.