1. Locke’s Doctrine of Essence
Locke’s introduction of the term “essence” into the metaphysical discussion of his theory begins with Drafts A, B, and C which precede the official publication of the Essay Concerning Human Understanding. The discussion is most intuitive with Draft B, in which Locke compares perceptions of matter and spirit and claims to posit substance as the basis for spiritual activity, giving us an idea of the essence of the spirit, “by supposeing a substance wherein thinkeing knowing doubting fearing & a power of moveing &c doe subsist, we have as cleare a notion of the essence of a spirit as any one hath of the essence of body…… And therefor from our not haveing any notion of the essence or the one viz Spirit we can noe more conclude its nonexistence, then we can of the other viz body” (Locke, 1990: p. 130). Unlike the drafts, Locke clearly distinguishes between substance and essence in his officially published The Essay Concerning Human Understanding, this claim was confirmed in correspondence with Edward Stillingfleet, Bishop of Worcester. When Stillingfleet pointed out that ancient philosophers sometimes equated substance with essences, Locke made it clear that he did not use substance in this sense, and that “the names of substances and essences had been misused”, substance is only used to represent substrates that support accidents.
In the official publication of the Essay, “essence may be taken for the very being of anything, whereby it is what it is” (Locke, 1690: p. 548). This contains two main points: the essence refers both to the existence of things and to what makes things what they are. The intrinsic constitution of things is that on which the sensible property rests, and hence it can be called essence. In addition, Locke argues that the excessive attention paid by the philosophers of the Academy to genus and species has led to the use of the term “essence” almost exclusively for such artificial constitution, leaving no time for real constitution, and that things can be logically classified under the names of species as long as they fit in with the abstract concepts that those names denote. Therefore, the two essences mentioned above one is a real essence and the other is a nominal essence. All properties perceived in a matter have a common cause and explanation, so that what is called real essence is the real constitution of any object. This special constitution is owned by the individual objects themselves and is not related to anything outside. The reason why everything has its own peculiar properties and is distinguished from other things is that it has its own limitation, and this limit is the so-called essence, which is an abstract idea with a name attached to it. In this way, the essence of the species and the abstract idea denoted by those species’ names are identical, there is a close connection between the name and the nominal essence. Therefore, all things contained in this idea are necessary to that species, and such an essence is called the nominal essence which is distinct from the real essence of the substance.
Locke’s distinction between nominal and real essences was made in the hope that people would learn that it is difficult to think barely about things in themselves, divorced from species differences and guided by words alone. Without a name, people cannot communicate, and in turn, if a species is given a name, it means that things are categorized and have a corresponding abstract idea. “One must do who would speak of the supposed real essences and species of things, as thought to be made by nature, if it be but only to make it understood, that there is no such thing signified by the general names which substances are called by.” (Locke, 1690: p. 617) If immortality is the criterion for essence, then those abstract ideas with names attached to them are undoubtedly essences. In Lockean theory, the essence of a substance refers to precisely the nominal essence of the substance (a point that will be discussed in detail in section III), which gives meaning, boundaries of use, and limited certainty to the name of the substance. The following section will provide a discussion of substances and their essential elements.
2. Substance’s Real Essence Reading
Although Locke made a distinction between substance and essence, the ambiguity that began in the drafts allowed for similarities in the formulation of the two terms, which prompted many successors to fail to make the correct distinction. Therefore, in the second and third sections of this paper, we will discuss the relationship between the essences mentioned by Locke (real essence and nominal essence) and the substances, so as to give a clear answer to the question of “what is the essence of the substances?” Among them, the idea of explaining substance in terms of real essence is the most popular, and the inquiry into the relationship between nominal essence and substance is particularly unfamiliar in comparison. In fact, the former idea will be proved to be wrong, real essence and substance belong to two different concepts, solving different theoretical problems, and forcing the two to merge in the understanding is very problematic; on the contrary, the nominal essence, which is ignored by people, can give the expected answer to the question of the essence of substance. This section will focus on the explanation of substance’s real essence explanation, while the third section deals with the relationship between nominal essence and substance and answers the question of what exactly is the essence of substance.
Scholars represented by Michael Ayers explain the idea of substance in terms of their real essence, which usually refers to the “real essence I mean, that real constitution of anything” (Locke, 1690: p. 584). Ayers agrees that substance and real essences are used for different explanatory purposes, but insists that the two are not onto-logically distinguished. He believed that when Locke articulated the idea of substance, he was expressing the real essence of things. Locke offers a hypothetical substance for the sensible property of natural coexistence, and assumes that these ideas flow from the special inner constitution or unknowable essence of that substance. Thus, the assumption of a substance is an assumption of a particular internal constitution or an unknown essence of the substance, and this marks the ignorance of the real essence of a substance.
In response to Ayers’s attitude, Edwin McCann attempts to demonstrate that substance is different from the real essence in terms of differences in the status of identity. (McCann, 2007: p. 87) He argues that real essences are the modifications of substance, and that the internal constitution of things can be (slightly) rearranged while remaining as the same substance. All things in existence (especially things we are familiar with) are susceptible to change, today’s grass becomes meat for the sheep and a few days later becomes part of someone’s. But the essence is unborn, and it is those named abstract ideas that are undoubtedly the essence. Because the real essence has the same beginning and the same end as a thing, while particular things are very changeable, thus it is impossible to discuss the real essence of particular things on the premise that they are unborn and indestructible. The only way to ensure that the essence of a thing is complete and undamaged is to take the idea established in the mind with a name attached to it, and regard it as the essence of the thing. No matter how individuals change, they are usually assumed to be constant. Thus, essences are only abstract ideas, and essences are only nominal essences and not real essences. Therefore, the state of identity of the substance and real essence is different, and Ayers’ tacit assumption that the two are onto-logically consistent is not feasible.
Jonathan Bennett, on the other hand, refutes the ontological consistency of the two in terms of Locke’s differing attitudes towards the substance and real substance, he argues that the greatest obstacle to Ayers’s interpretation is “the inability to account for the way Locke writes about the two sides of the substratum” (Bennett, 1987: p. 204), Locke consistently describes the idea of substance as perplexing and obscure, but has not so commented on the real essence. Locke “implies that we should exclude ideas about internal constitution from our everyday thinking about the world because they cannot do any work for us” (Bennett, 1987: p. 204). In response, Ayers invokes a polemical strategy in Locke’s theory in order to respond to Locke’s apparent contradiction of substance: ridiculing “substance” and “accidents” for their lack of utility in philosophy but continuing to use them. In fact, the view that “substance and accidents are of no use in philosophy” was put forward by Locke in his discussion of the pure substance in general, it was found that the idea of substance is only “a supposition of he knows not what support of such qualities which are capable of producing simple ideas in us; which qualities are commonly called accidents” (Locke, 1690: p. 377). These properties that give us simple ideas are commonly called accidents, for which the term “substance” is found to support the accidents. Pure substance in general marks a support that one assumes but does not know what it is and these properties cannot exist without support. The name “substantia” corresponds to the English meaning of standing under or holding. If we translate the Latin words “inherentia” and “substantia” into the English words “sticking-on” and “underpropping”, it will help us to better understand the doctrines of substantia and accidents.
Indeed, the Essay’s account of substance barely overlaps with the passages on the real essence, and never even hints that the above terms explore the same issue. The Essay contains five parts treatment of substance and real essence, three of which set them side-by-side, while the remainder treats the two terms as separate concepts from each other. E2.31.13 is one of the rare clips in which both appear at the same time, in which Locke further reinforces the idea that they are different subjects. If Locke really does equate the idea of substance with the real essence, there is no reason to describe substance as hypothetical or confusing ideas. The real essence is not a basis for categorizing substance, nor can it be implied metaphorically in the untrained mind. Real essence cannot do any work for people because they don’t know what the internal constitution of any kind of thing is, which is a huge difference from Locke’s position on the idea of substance. On the question of “explaining the real essence of the sensible property of objects”, Locke’s attitude has always been that “in the study of nature we must beware of hypotheses and wrong principles” (Locke, 1690: p. 873). In the case of individuals, for example, we can only observe the characteristics of their co-existence, but cannot discover the real essence on which the properties of the object depend, nor can we grasp by this the nature and character of this species, and we have to stop at what we can derive from special experiments. Locke severed the link between experimentation and the discovery of deeper causes, arguing that the only basis for making judgments about the coexistence of matter is through experience, observation, and natural history. It’s as if doctors don’t need to and can’t know about diseases that have nothing to do with the senses; it’s enough to know the immediate source of the damage and effectively differentiate between the symptoms of similar diseases in order to administer the corresponding treatments.
Locke does describe us as ignorant of both the substance and the real essence, but his approach to the two concepts is markedly different. Unlike the description of the idea of substance as hypothetical or confused and unclear, one’s understanding of real essence is not even vaguely defined. Locke states that ideas that make our complex ones of corporeal substances, are of these three sorts (Locke, 1690: p. 383): the idea of the primitive properties of things, the sensible secondary properties, and the tendency of substance to be capable of producing change or receiving change. Of these, secondary properties are the power of substance that makes up the bulk of the idea of substance. Even if we accurately collect all the secondary properties or power of a substance in a complex idea, we do not thereby gain an idea of the essence of that thing. Since the set of sensible properties flows from the real essence rather than the real essence itself, the lack of knowledge of both the real essence and the idea of substance implies that there are two concepts here rather than one. Substance and real essence seem to be used to answer different questions: whereas Locke discusses the substantiation of material and mental properties in passages relating to substance, when it comes to real essences he is concerned with causal explanations of the observable properties of objects. There is, therefore, no important connection between Locke’s doctrine of substance and the doctrine of the real essence. All that Locke says about the relationship between the two is that the properties supported by substance all derive from the real essence of things.
3. Nominal Substance and Meaning of the Name of Substance
Since the path of explaining substance in terms of their real essence doesn’t work, what are we referring to when talking about the essence of substance? Unlike the nominal essence and the real essence which manifest themselves in agreement in simple ideas and model, “a real essence, distinct in substances from those abstract ideas of them, which I call their nominal essence” (Locke, 1690: p. 584), this is to say that the dilemma of the real essence in the interpretation of substance does not completely block the influence of the doctrine of essence on substance, but on the contrary gives rise to the possibility of exploring the essence of substance from the nominal essence. When we speak of the essence of substance, in addition to the aggregates formed by sensible properties, the idea of unknowable causes that unite simple ideas is also part of the essence. In classifying substance, we only look at abstract ideas, not at the inner constitution, not at the so-called “forms of substance”. If we take the criterion of the immutability of essences, then there is no doubt that those abstract ideas to which names are attached are precisely essences, and the essence of a substance in Locke’s theory refers to the very nominal essence of the substance. The nominal essence gives the meaning of substance’s name, as well as using boundaries and limited certainty. At this point, the question of “what determinate content a substance can derive from Locke’s description of essence” is fixed on a discussion of the meaning of the name of a substance. There is a natural affinity between the essence of things (species) and general names; things are assembled from human hearts, but it is only their names that bind them tightly. Everything that exists is particular, and in order to avoid the endless expansion of the names of particular ideas, most of the words in language, by virtue of their endowed significance and utility, can always be rendered, by reason and necessity, into general nouns, things have no universals of their own, and all generalizations are the product of an understanding that finds similarities in things. Generalized names are embedded in the common properties of something, and one separates the special episodes concerning time and space in the complex idea of special things. By omitting the special elements of a complex idea, the generalized text, by means of abstraction, is able to represent the majority of individuals, and the things that correspond to this idea are naturally classified under that name. A generalized name is the mark of an abstract idea in the human mind, through which the human heart obtains the universal terms of the physical idea.
As with all generalized nouns, it is species that are denoted by the names of substances as markers of complex ideas, and particular substances can be included in the same concept and denoted by the same name as long as they are compatible with these ideas. It is worth noting that the species of things is a product of the understanding and relies only on a collection of ideas formed by man rather than on the actual essence of things, when one speaks of the essence of things, one means the measure and limits by which things can be distinguished, and by which they are distinguished by the properties common to the species to which they belong, “which is nothing but that abstract idea to which the name is annexed” (Locke, 1690: p. 580), that is to say, it corresponds to the complex idea represented by the name. In fact, the essences described above are all that one “knows” about the essence of natural substance, which Locke calls the nominal essences (that complex idea denoted by a particular name), as distinguished from the real essences, on which the nominal essences and the properties of things depend.
Since species can only be defined in terms of a nominal essence and that essence can only come from human understanding, where is the line that defines species? There is no complete and universally agreeable definition does not mean that nominal essence is formed arbitrarily, the formation of nominal essence requires the fulfillment of the following conditions: First, the ideas contained in that nominal essence must be compactly connected, that is, they can be formed only on the basis of nature, and complex ideas of entities are formed by people copying the ideas united in nature. In this way, illusions are excluded from the mind and ideas can be used normally in conversation and daily life. Secondly, the number of linked special ideas is constant, neither more nor less. This is to ensure the homogeneity of complex ideas: a difference in the number of ideas would result in two different ideas. The most obvious of these sensible properties are figure and colour, which are the most important parts of the identification of species. But these names are not rigorous: they are neither defined nor contain simple ideas that cannot be added to or subtracted from, nor do they encompass the full range of ideas that are naturally connected in nature. Therefore, the substances we are arguing about are mere illusions that do not give insight into the various properties, and even if the nominal essences of substances are copied from nature, these real essences are incomplete.
Even so, the idea of substance has been abused in language which has led to the loss of its utility as a text. Specific analyses can be attributed to the following types: First, we know the term “substance”, but we do not understand the clear idea of what it represents; Secondly, we know about the idea of complex substance but have no detailed account of their content; Third, the name of substance does not always mark the same idea; Fourthly, the idea of substances does not correspond to the real essence of things, and becomes an imaginary “substances such as never have been, and filled his head with ideas which have not any correspondence with the real nature of things” (Locke, 1690: p. 680). The above-mentioned misuse of substance in language results in people not being able to express the connotations of the idea of substance correctly and thus not being able to add to real knowledge. It is worth noting that the most common mistake people make in interpreting the idea of substance is mistaking words for things, if one insists on considering words as physical objects, then when the entity is applied to the infinite God, the finite spirit, and the object respectively, do they represent three modifications of the substance? Or is it the idea of substance with three different meanings? The former would lead to the question of whether the meanings of the three substances are consistent and what is the common property of substance; the latter would imply that the term “substance” represents three different ideas, to which one should create three different names. The problem is that we do not have a clear meaning of substance, whether it is one or three. A name without an idea lacks meaning and is nothing more than an empty voice, well a complex idea without a name cannot express and convey ideas freely.
The name of substance denotes both our ideas and real things, and in order to make proper use of the various names of substance, it is necessary to make sure that the using of substance’s name is compatible with real things, that is to say, the meaning of substance’s name is compatible with both of them. While the names of substance need to refer to models (not very strictly) and cannot be completely arbitrary, this is not easy. The conceptions of things formed by man as a child are often incomplete, children always learn words before they use them to represent ideas, and after learning them they are apt to use them without thinking, this habit of using words becomes more and more natural with age, and eventually takes root in public usage. But public usage based on habit is a loose, indeterminate rule, and everyday conversation shows enough for most people to grasp its true meaning when it is much harder to form definite ideas. Moreover, “all the sciences and parts of knowledge have been so overcharged with obscure and equivocal terms, and insignificant and doubtful expressions” (Locke, 1690: p. 681), the common language used in daily conversation, though confused, is sufficient for daily use, and therefore for philosophers to be more intelligibly understood if they “have words wherewithal to dispatch their ordinary affairs” (Locke, 1690: p. 685).
Therefore, Locke points out that we should not only explain the idea of substances through definitions, but also study natural history to further examine the nature of things in order to correct and refine the names of the substance. Locke reveals the significance of substance’s name through fieldwork and definitions, which denote the ideas that people form about species, there are primary and other properties in each species, and the other properties are dependent on the primary properties, so that the names of the species are derived from the ideas that clearly mark the species. One can observe the primary properties of substance, and they are the most obvious and constant parts, e.g. man is a substance that is both animal and rational, but figure should also be added to the complex idea expressed by the word, because Locke thought that “for it is the shape, as the leading quality, that seems more to determine that species, than a faculty of reasoning” (Locke, 1690: p. 692), figure is the primary quality of man, and the ability to reason is not common to all. These primary properties must be known through physical observation, and seeing the horse in person is clearly a better option than imprinting the horse’s figure in one’s mind through words. If one wishes to understand the meaning of substance, it would be better to enumerate the simple ideas in them, but since many of the simple ideas in substance are powerful and incapable of visibly stimulating the senses, the meaning of substance’s name is destined to be incompletely revealed. Thus, the meaning of substance names is indeterminate, and generalized substance names are for general use only, and placement in philosophical discussions can present difficulties.
4. Unknowable Essence of Substance
Through the above, we understand that the essence of substance refers to nominal essence, and that real essences cannot have the desired effect in explaining substance. Despite figuring out what the essence of a substance is, it is still impossible to gain complete knowledge about it, and inquiry into the essence of a substance inevitably leads to the negative result of a double ignorance of the substance and its essence. But every step and discourse in between completes the closing of the loop in empiricism, and it can be said that the double agnosticism of substance and its essence is the corollary and ultimate fate of empiricism. This section extends the discussion to empirical agnosticism, starting from the agnosticism of substance and its essence. Gives a new perspective on agnosticism and a rational explanation for the essential agnosticism of substance.
Real essence interpretation can’t properly reveal the relationship between substance and essence, so I choose to use property as a mediator to link substance to essence. Locke characterizes substance and real essence respectively in the following way: on the one hand, the properties should rest in, belong to, be supported by, reside in, subsist and exist in, and result from substance; on the other hand, the observable properties of substance flows from, depends on, is centered in, is united in, is founded upon, and is based upon its unknown real essence or internal constitution. That is, both substance and real essences are in some way the basis of property, but we lack knowledge of them, Locke teaches a double ignorance of both substance and real essences. The fundamental reason why the real essence cannot be used to define species is that the human mind does not have a clear and complete idea of real essence, none of the faculties of man has access to the knowledge of substance; all that is available is a collection of ideas of perceptible properties, which is far from the kind of inner constitution from which the collection of properties originates. Further, without knowing the real essence, it is impossible to know with certainty the properties that flow from it, or which properties cannot be separated from the particular essence, and thus it is impossible to determine which properties are missing in particular. For example, how many properties rely on the real essence of gold, and which properties whose absence would result in the non-existence of gold. A series of questions interlinked, no matter forward, reverse backwards, can reach the same conclusion—grasping the real essence is a cognitive dimension beyond the reach of human faculties, and the subtle machinations of things are beyond the reach of even the most intelligent and clever person. The incompatibility of the real essence interpretation with Locke’s theory of the origin of ideas is not a reason to think that he disagrees with the substance interpretation, “for he himself acknowledges that his doctrine of substance conflicts with his theory of the origin of ideas” (Bolton, 1976: p. 502).
Not only do we not have complete knowledge of the real essence, but we have not gained complete knowledge of the essence of substance: the nominal essence. Defining the boundaries of species is a product of man, who classifies species only to make it more convenient to include them in general terms, so that all individuals with that complex idea can be recounted effortlessly and repeatedly in short words. “How much the making of species and genera is in order to general names; and how much general names are necessary, if not to the being, yet at least to the completing of a species, and making it pass for such, will appear” (Locke, 1690: p. 614), “there is no essence in nature, because there is no natural sort. there is only a belief in essences based on artificial and nominal sorts. Each sort is therefore linked to the state of our knowledge” (Vienne, 1993: p. 153), so that generalized ideas of substance are not exact images of natural models, and that all generalized names and abstract ideas mostly aim at being efficiently expressed and communicated. People think of things without examining any real essence or form of substance, and therefore in this case do not really inquire into the real and precise essence of things, nor do they examine all the property of things and their inner constitution clearly. The generalized names so formed are one-sided, incomplete and inadequate, but are sufficient to give rise to ambiguous ways of thinking and talking. For example, when talking about things in terms of extension and solidity, the word “object” can be used to denote them, and when the terms life, sensation, spontaneous movement, etc., are added, the word “animal” will be used to denote them. That is to say, these abstract, generalized ideas can be fully “in respect of a certain established relation between them and certain names which are made use of to signify them” (Locke, 1690: p. 610), but their meaning cannot be extended to “anything existing, as made by nature” (Locke, 1690: p. 610).
Thus, in the matter of substance and its essences, one can only assume that the real essences of substance exist without knowing them with certainty, and that the nominal essences of substance would attribute these essences to a particular species to which the substance belongs. Up to this point, our discussion of the substance and their essences in Locke’s theory remains negative and limited, and one concludes that the substance and their essences are unknowable due to the lack of certain knowledge to grasp the true mysteries of nature. Indeed, when Locke talks about things we do not know or lack ideas about, it is difficult to figure out “whether he is talking about things we happen not to know or whether he thinks that our ignorance is sometimes incurable and that there are things we do not know in principle”. (Atherton, 1984: p. 415) These difficulties are most evident in Locke’s discussion of “substance.” Agnosticism is a corollary of the philosophical context of empiricism, in which sensation and perception are the basis and entire source of knowledge, and knowledge is not limited to this, the human mind is capable of comprehending things beyond the boundaries of sensation. Empiricism draws an impenetrable boundary to human knowledge, and all discussion of what lies beyond it can only be regarded as unknowable.
The clarification of substance, real essences, and nominal essences helps to make sense of the relationship between substance and essences in Locke’s theory, a relationship that closes the loop in empiricism with the conclusion of agnosticism, and influences the way people understand the world: recognizing only what can be grasped. Beckley had asserted that only materialists draw agnosticism conclusions, and it was not long before Hume proved Beckley’s conclusion wrong. Similarly to Hume, Kant believed that the world was unknowable, or at least not completely knowable. Kant claimed that Hume had awakened himself from his dream of solipsism, and that Kant’s agnosticism corresponded to the agnosticism of the thing-self, his agnosticism is “a premise that can and should be preserved for the progress and perfection of human morality”.
To this point, the discussion of substance and their essences in Locke’s theory extends to the issue of essential agnosticism, and the analysis of the relationship between the two has yielded negative and limited results; the clarification of the details in between helps us to see the closed loops of substance, essences, and agnosticism in Locke’s theory in their fullness with a new perspective, and to understand the impact of this theoretical legacy on the philosophies that have followed it.
5. Conclusion
To complement the scholarly discussion of the essence of Lockean substance, this paper discusses substance from two perspectives, nominal essence and real essence, respectively, and ultimately concludes that the essence of substance is nominal essence, and that real essence is anachronistic in explaining the idea of the substance. Just as we are agnostic about substance, we do not have complete knowledge of the essence of substance (nominal essences), and Locke teaches the dual agnosticism of substances and their essences, which is a corollary of empiricism. Up to this point, in order to have a complete exposition and conclusion of the problem of substances and their essences, the paper extends this problem to empirical agnosticism. Not only does it further allow substances and their essences to complete the closure of the loop in Lockean theory, but it also adds a new perspective of understanding to empirical agnosticism