Defining without Essences: Ibn Taymiyya’s Critique of Aristotelian Logic

Abstract

This paper examines Ibn Taymiyya’s (1263–1328) critique of the Aristotelian logical tradition, with a particular focus on his theory of definition (ḥadd). Ibn Taymiyya argues that Aristotelian logic, premised upon fixed metaphysical categories, fails to serve as a practical instrument for epistemic inquiry and knowledge production, as it claims. Ibn Taymiyya’s critique can be divided into two main classes: general and metaphysical. His general criticisms undermine the validity of Aristotelian definitions through multiple dialectical arguments such as regress, disagreement, and redundancy, showing that definitions are not epistemically useful. His metaphysical criticisms, on the other hand, strike at the foundations of Peripatetic metaphysics by rejecting the distinctions between a) quiddity and its existence, and between b) essential and concomitant predicates. I have also argued that Ibn Taymiyya’s position cannot be reduced to nominalism, empiricism, or conventionalism. Rather, his theory of meaning aligns more closely with modern pragmatics, wherein speech acts derive their meaning from their communicative, intentional, and contextual functions.

1 Prelude to Aristotelian Theory of Definition

The notion of definition plays a cardinal role in Aristotle’s method of philosophizing, as he considers it a cornerstone of scientific investigation.¹ The prototypical aim of defining x is to obtain an accurate description of the real properties of x that can be used in the rest of scientific inquiry. In the Metaphysics, Aristotle² introduces one reason for investigating the notion of definition: it can reveal the essence of the definiendum. In other words, the structure of the definiens is meant to reflect the structure of the essence of the definiendum. In the Metaphysics (8.1 1042a17–21), Aristotle writes:

Since essence is substance and the account of this [essence] is a definition, for this reason, definition and the as-such were discussed. And since a definition is an account and an account has parts, it was also necessary to know the parts, [i.e.] to know what sort are parts of the substance and what sort are not, and if these are the same [as the parts] of the definition.

Since definitions account for essences, they also account for the formal cause(s) of the definiendum.

Another qualification, in the Metaphysics, is that Aristotle seems to restrict the definiendum to “simple terms” (viz. x is a simple term if its cause is no other than itself). Differently, In the Topics (6.4 141b27–30), Aristotle writes that definitions should follow the method of identifying the genus and the differentia of the definiendum. The reason is that a species’ genus and differentia are conceptually prior to the species itself.

      …since a correct definition must define a thing through its genus and its differentiae, and these belong to the order of things which are without qualification more intelligible than, and prior to, the species. For destroy the genus and differentia, and the species too is destroyed, so that these are prior to the species.

The “priority” and “intelligibility” locutions here are meant to be in explanatory terms. In other words, they are meant to reflect a certain ontological priority, as Deslauriers [19] notes. Given this genus-differentia approach, it is clear that definitions need to have parts that reflect the different components of the definiendum. But this raises an aporia for Aristotle, how can these different parts form a unity within the definition? In the Metaphysics (7.10 1034b20–24), he writes:

Since a definition is a formula, and every formula has parts, and as the formula is to the thing, so is the part of the formula to the part of the thing, we are already faced by the question whether the formula of the parts must be present in the formula of the whole or not.

In the Posterior Analytics (1037b13–14), he presents the same aporia in a different form: why is it the case that “the formula of which we call a definition” is one? Why are the genus and differentia of a “person” constituted by the unity of “animal” and “biped” rather than two separate forms?³ In the Metaphysics, Aristotle examines two solutions, one in 7.12 and the other in 8.6.⁴ In the latter section, Aristotle thinks that the aporia is erroneous because it presupposes a fallacious assumption, namely that the parts (e.g., “animal” and “biped”) that construct the unity of definition must exist separately. This is basically Plato’s theory of separate forms that Aristotle disagrees with (viz. a substance can be analyzed into parts that are distinct from their particular instantiations). This does not mean that Aristotle (1045a23-26) is denying that the definiendum has parts, he just rejects that these parts are de facto separable. Rather, he understands these different parts as a unity of matter and form. Matter represents the potentiality of the genus, while form represents the actuality of the differentia(e). For instance, an object defined as a “round bronze” is not constituted by two separate forms of “roundness” and “bronzeness”; rather “bronze” is the potential-matter-genus part of the substance, and “round” is the actual-form-differentia(e) part of the substance. Both parts refer to different components of the definiendum.⁵ Another approach to definition in the Posterior Analytics (2, 91a, 1–5) is that it has the function of explaining the definiendum is by revealing its essence. In other words, “to know its essential nature is, as we said, the same as to know the cause of a thing’s existence, and the proof of this depends on the fact a thing must have a cause” (2, 93a, 5–10).

To sum it up, Aristotle presents three main approaches to definition: a) in the Metaphysics, it aims to disclose the formal cause of the definiendum; b) in the Topics, it plays a classificatory role through the genus–differentia model; and c) in the Posterior Analytics, it serves an explanatory role for the definiendum by revealing its essence. These Aristotelian insights were later codified into more general principles by subsequent thinkers such as [17, p. 238], where an Aristotelian definition must have the following criteria: a) reveal the essence of the definiendum, b) not circular (i.e., does not directly or indirectly contain the defined subject), c) not negative (if possible), and d) not framed in metaphorical language.

2 Reception of the Aristotelian Theory of Definition in Islamicate Philosophy

It is a well-known historical fact that early Islamicate philosophy was partially shaped by the translation of Aristotle (and other Greek philosophical texts) from Greek and Syriac into Arabic.⁶ This also includes translating many of the Peripatetic and Neoplatonic commentaries on Aristotle. The theory of definition has been a central concern in the Islamicate logical tradition, particularly in the debates on conceptualization (taṣawwur) and syllogistic reasoning (al-qiyās). Many logicians argued that theoretical knowledge cannot be attained without definitions, making them fundamental to intellectual inquiry. Figures such as al-Ghazālī (d. 1111) and alā’ al-Dīn al-Ṭūsī (d. 1473) emphasized the necessity of definitions in structuring knowledge and understanding. However, this view has been met with substantial criticism, spanning epistemological, metaphysical, and pragmatic concerns. Critics, including Fakhr al-Dīn al-Rāzī (d. 1209) and Ibn Taymiyya (d. 1328), questioned the viability of strict Aristotelian definitions and proposed alternative approaches to knowledge acquisition.

Many Islamicate logicians defended the need for definitions based on the following argument: a conceptualization is either necessary (ḍarūrī) or theoretical (naẓarī). The former is extremely limited and cannot generate knowledge (beyond necessary logical propositions). On the other hand, the latter is the basis of all theoretical knowledge, which cannot be attained except through definitions. For instance, al-Ghazālī [5, p.12] writes that “everything that is not known innately can only be known through definition.” Similarly, alā’ al-Dīn al-Ṭūsī [10, p. 194], writes: “That which is not self-evident has an innate path to knowledge, but its complete knowledge is only achieved through definition.” In his treatise The Terms Used in Logic (Alfaz al-Musta’malah fi al-Mantiq), al-Fārābī [3, p.78] explains the notion of complete definition:

      …since the complete definition pertains only to a singular entity, one can employ it to answer the question ‘What is it?$'$ and to signify how that entity is distinguished from everything else. A definition acquaints us with two aspects of the thing: the first is that it identifies the essence (dhāt) and substance (jawhar) of the thing; and the second is that it makes known that by which it is set apart from all other things.

Hence, a complete definition is a definition that states what a thing is and what a thing is not.⁷ Following Aristotle, al-Fārābī [2, p.4] considers that a complete definition generates complete knowledge of the definiendum, while an incomplete definition can only lead to knowledge of accidental properties of the known object. In a similar fashion, al-Ghazālī [6, p. 65], in The Standard Measure of Knowledge (Mi‘yar al-‘Ilm fi al-Mantiq), writes:

Know that when someone asks, ‘What is it?’ concerning a thing, that question is a quest for its quiddity (māhiyya). Thus, whoever has come to know the quiddity and states it has indeed answered. Now, the quiddity is only realized by the collective totality of its essential, constitutive attributes, so as to furnish a complete answer—namely, by articulating its definition (ḥadd). Should one omit any of those essential attributes, the answer would remain incomplete.

Also, al-Ghazālī [6, p. 42] notes that: “Writing signifies utterance, and utterance signifies the meaning that resides in the mind; that which is in the mind is a form (or image) of what exists in external reality.” The implication here is that the aim of a definition is not merely verbal differentiation; rather, it is to apprehend the corresponding reality of the definiendum and ascertain how well it corresponds to actual existence. The same thought is expressed by Jābir ibn Ḥayyān [22]:

Indeed, the purpose of a definition is to encompass the very essence of the definiendum (al-maḥdūd) in its true reality, so that nothing belonging to it is left out, and nothing extraneous is brought in. For this reason, it has been said that a definition admits neither augmentation nor diminution.

To sum up those views, the most comprehensive definition of a “definition” was presented by al-Rāzī [9, p. 300] in The Great Book of Logic (Al-Manṭiq al-Kabīr) as follows:

A definition is understood in various ways. One explanation states that it is a statement that indicates the quiddity of a thing, while another defines it as a phrase that provides knowledge (ma‘rifah) of something. A proper definition conveys the essence of what is being defined, conceptualizing its quiddity (māhiyyat al-shay’) in the mind (al-nafs) …Definitions can be either complete (kāmil) or incomplete (nāqiṣ). A complete definition fully captures the quiddity of a thing by including both its genus (jins) and differentia (faṣl), where the genus provides a general classification and the differentia distinguishes it from other entities within that category…Since a complete definition (al-ḥadd al-kāmil) always consists of both genus and differentia, no definition is valid without them …Thus, a proper definition (al-ḥadd al-ṣaḥīḥ) must encompass both the general and distinguishing characteristics that constitute the quiddity of a thing.

So, in short, a definition is a statement that indicates the quiddity of an object, either by 1) fully capturing its essence or 2) by providing complete knowledge of it. A definition is complete if it consists of both a genus (which classifies the entity) and a differentia (which distinguishes it from others within that category). This was the perceived understanding that was shared among most of the Islamicate philosophers.

An important point to note is that most Islamicate philosophers use the term quiddity (māhiyyah) when discussing the realities of entities, since quiddity had become a central concept in the Peripatetic and Neoplatonic commentaries on Aristotle. As an illustration, for Ibn Sīnā, quiddity is meant to designate the “what-it-isness” of an object. That is, explicating its fundamental structure and intelligibility to the mind since one cannot conceptualize a thing unless one grasps its quiddity. For that reason, a complete definition is successful only if it designates the quiddity of the definiendum, regardless of its mode of existence (i.e., whether it exists and how it exists).⁸

Returning to the notion of definition, and as mentioned earlier, there were many criticisms of this perceived view of definition for various reasons. In this article, we are going to explore the chief member of the group of Islamicate philosophers who opposed it: Ibn Taymiyya.

3 Ibn Taymiyya and The Refutation of the Logicians

As said in the previous section, Ibn Taymiyya (1263-1328) was one of the opponents of the Aristotelian theory of definition as part of his general project to attack Aristotelian metaphysics. As we will see in later sections, some of Ibn Taymiyya’s arguments echo the thoughts of the Greek Skeptics and Sophists. Interestingly, we do not have even a shred of strong historical evidence that the texts of the Sophists were directly translated into Arabic or were accessible to Ibn Taymiyya. Likewise, it is well known that the texts of Greek Skeptics were not accessible either as emphasized by [37, p. 26]. Despite that, we know that Islamicate philosophers were acquainted with some of the Sophists’ writings indirectly through Plato and Aristotle. For instance, Ibn Rushd [23] (d.1198) wrote a critical commentary on Aristotle’s Sophistical Refutations. Also, some of the Stoics’ writings were known to Islamicate philosophers through the interpreters of Aristotle (e.g., Yahya al-Nahawi and Alexander the Aphrodisi) as well as through the translation of the works of Gaskabis and Galen (e.g., Ibn Miskawayh’s translations) (see [33, p. 73]).

That said, Ibn Taymiyya was quite original, given his historical context, when presenting his criticism of Aristotle, which culminated in his magnum opus The Refutation of the Logicians (al-Radd ’alā al-Manṭiqiyyīn). One of the advantages of Ibn Taymiyya’s philosophical method in The Refutation is that he does not get distracted by perennial debates over marginal postulates of the Aristotelian logical tradition. Rather, he just focuses on a few fundamental doctrines and challenges them consistently from different directions (see [21, p. xiv]). One could classify Ibn Taymiyya’s criticisms into two general classes: the first is a list of general criticisms, which raise a variety of semantic and epistemic points. The second class of objections is chiefly against foundational concepts of Aristotelian metaphysics, specifically the following two distinctions: a) quiddity and its existence, and b) what is essential to quiddity and what is concomitant to quiddity. We will examine each class of criticisms in order.

4 Ibn Taymiyya’s General Criticisms

In The Refutation, Ibn Taymiyya is mainly concerned with targeting two things: 1) the Aristotelian theory of definition (ḥadd), and 2) the Aristotelian categorical syllogism.⁹ At the beginning of the treatise, Ibn Taymiyya [24, p. 46] makes it clear that the foundational errors of logic stem from flawed metaphysical principles.

It has become clear to me that much of what they (i.e. the philosophers) set forth in their principles concerning …logic is itself among the foundations of their erroneous position in matters of metaphysics (ilāhiyyāt). For example, what they have stated about quiddities (al-māhiyyāt) being composed of those qualities they call ‘essential attributes’ (dhātiyyāt), and what they have asserted regarding restricting knowledge to the methods of definitions and demonstrative syllogisms (al-barāhīn). Indeed, this applies as well to what they put forward concerning definitions—by which conceptions (taṣawwurāt) are recognized—and applies as well to the forms of syllogism (al-qiyās) and its apodictic subject-matter (yaqīniyyāt).

Also, Ibn Taymiyyah [24, p. 46] conceives the role of definition in the logical enterprise as follows:

They [i.e. the philosophers] built their system of logic upon the notions of “definition” (al-ḥadd) and the “demonstrative syllogism” (al-qiyās al-burhānī), as well as its various types …The method by which one attains conception is ‘definition,’ whereas the method by which one attains assent is ‘syllogism.’

Accordingly, and given the foundational role of the notion of definition in Aristotelian logic, if Ibn Taymiyyah manages to show that the theory of definition is fundamentally flawed, he would have undermined the core of Aristotelian logic without much effort. Even though he also attacks demonstrative syllogisms later in the treatise. In the first part of The Refutation, Ibn Taymiyya offers two types of critiques of the notion of definition. The first consists of general criticisms, while the second targets specific metaphysical concepts. In this section, we will explore his general criticisms—some rooted in epistemic and pragmatic considerations, and others grounded in semantic and empirical concerns. Here, I will only cover the five most prominent arguments.¹⁰

The first one is epistemic, namely the regress argument. He writes,

Thus it is said: If “definition” is the statement uttered by the definer, then either one has already come to know the definiendum (almaḥdūd) by way of some other definition, or one has come to know it without any definition at all. If the former is the case, then discussion of this second definition is no different from the discussion of the first—leading to a circularity (dawr) or an infinite regress (tasalsul) in the causes (al-‘ilal) and reasons, both of which the rational consensus deems impossible. If, however, one came to know it without a definition, then their original premise—namely, that “it cannot be known except by definition”—is thereby invalidated [24, p. 49; emphasis is mine].

If the definiendum can be known only through the process of definition, then we have an infinite regress (tasalsul). Why? Because the constituents of a definition will be only explainable through other definitions, adinfinitum. The other option is to assume, like Aristotle, that the words used in the definition are “simple” in the sense of being non-definable, but this means that it is possible to apprehend concepts by other means (i.e., other than definitions), which goes against the logicians’ doctrine of “no concept can be formed except through definition”.

The second epistemic objection is based on the problem of peer epistemic disagreement. Ibn Taymiyya [24, p. 50] explains:

Until now, it is not known that anyone has established a sound definition in accordance with their principles. Indeed, among the most well-known examples is their defining “man” as “the rational animal,” which is subject to the famous objections. The same goes for the definition of “the sun,” and the like.

In fact, when the latter-day grammarians ventured into definitions, they proposed some twenty-odd definitions for “the noun,” each one meeting with objections based on their own principles…If the conception (taṣawwur) of things was truly conditional upon [these] definitions, then up to the present hour, humankind would not have conceived anything at all of such matters.

There are two potential points raised here. The first is a skeptical argument from peer epistemic disagreement—the thought that since the relevant experts disagree about basic definitions in their own fields, then there are no true definitions.¹¹ The second point is that despite these disagreements, epistemic peers are still able to form judgments and generate exchangeable knowledge. However, this would not have been possible if the process of conceptualization (and hence judgment) were only contingent on definitions. Consequently, definitions are not necessary for conceptual formation.

Thirdly, Ibn Taymiyya [24, p. 53] advances an argument based on sense perception:

The entities one conceives (al-mawjudāt al-mutaṣawwarah) are either those a human perceives through his external senses—such as taste, color, scent, and the bodies that bear these attributes—or else one conceives them by his internal faculties, in the same way one envisions inwardly perceptible states, such as hunger and satiety, love and hate ... All these conceptions are fully independent of definition.

Sextus Empiricus [36] made a similar point about the connection between conceptual formation and the senses. Nevertheless, Ibn Taymiyya is not interested here in defending some form of empiricism, rather he only wants to show that one can understand some concepts without being able to define them.¹² It is perfectly conceivable to understand—through some form of sensation—the concept “red” without knowing its definition (viz. “it is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres”). Interestingly, this can be thought of as one formulation of Jackson’s well known knowledge argument against physicalism, although the target here is the theory of definition.¹³

Fourthly, Ibn Taymiyya puts forward his argument from epistemic relativism.

…It may be said, “They [the philosophers] themselves acknowledge that some conceptions are self-evident (badīhiyyah) and therefore require no definition …In that case, one should reply: Determining whether a given piece of knowledge is “self-evident” or “theoretical” (naẓarī) falls under relative, comparative matters—just like a “proposition” (qaḍīyah) can be either certain (yaqīnīyah) or merely conjectural (ẓannīyah) [24, p. 55; emphasis is mine]

Hence, even if (some) logicians avoided the aforementioned regress argument by admitting that some concepts are self-evident, there is still another predicament. Namely, there is no distinct way of determining which concepts are self-evident and which are in need of a definition. Thus, definitions, on this view, are relative and unstable.

Finally, Ibn Taymiyya [21, p. 16] presents a Menoesque argument from epistemic redundancy against Aristotelian definitions. For any definiens x, it is the case that the hearer either knows its definiendum, or they do not. If it is the former case, then x is epistemically redundant as it does not add to their knowledge. Yet, if it is the latter case, there is no way to check whether x can generate knowledge as it is just a declarative proposition (qaḍiyya khabariyya) with no supportive evidence. But since the definer is fallible, x may be wrong; therefore, defining without accompanying evidence does not contribute to knowledge. Another related point that Ibn Taymiyya stresses is the alethic uselessness of definitions. It seems, after all, that definitions are epistemically valuable—especially in syllogistic reasoning— only if they are true. Nonetheless, one cannot check the truth value of the definiendum by only consulting the definition itself as it is just a declarative proposition that is alethically neutral. In his words [21, p. 17], “In short, forming a concept of the definiendum by means of definition is impossible without knowing the truthfulness of the definer’s statement. But the truthfulness of his statement cannot be known merely by uttering the definition. Hence, the definiendum cannot be known through definition.”

As mentioned earlier, Ibn Taymiyya presents more general arguments against the Aristotelian theory of definition, but the ones discussed above are the most prominent. So far, what he attempted to show, is that any theory of definition will be either circular, infinitely regressive, or epistemically redundant. In the next section, I will turn to his fundamental metaphysical criticisms, which he develops in greater detail.

5 Ibn Taymiyya’s Metaphysical Criticisms.

One of the main tasks of Ibn Taymiyya in The Refutation is to argue that the philosophers’ metaphysical doctrine of classifying properties into essential and accidental is misguided. He starts by summarizing the philosophers’ (viz. primarily Avicenna’s) classifications of the attributes. He divides them into three groups [24, pp. 105–106]:

• Group 1) Essential vs. Accidental predicates

And they say: the essential predicate (al-maḥmūl al-dhātī) is that which is internal to the reality (ḥaqīqah) of the subject (al-mawḍū’) …As for the accidental predicate (al-maḥmūl al-‘araḍī), it lies outside the essence of that reality.

The typical examples of essential and accidental predicates are the “rational” predicate for humans and the “laughing” predicate for humans, respectively.

Accidental predicates can be further divided into:

• Group 2) separable (‘āriḍ) vs. inseparable (lāzim) accidents

A separable accident is a contingent attribute that may fail to accompany the subject, such as “standing” in the case of humans. By contrast, an inseparable accident is a concomitant attribute that always accompanies the subject and cannot be separated form it, even though it lies outside of its “reality”. Then, inseparable accidents themselves are further divided into a third group:

• Group 3) a concomitant of existence (lāzim li-wujūd al-māhiyyah) and a concomitant of quiddity (lāzim lil-māhiyyah).

The former is an attribute that the follows from the existence of quiddity, but not from the quiddity itself. For instance, the “shadow” of a horse concomitantly follows from the existence of the “horse”, but it does not follow from its quiddity. However, the latter attributes follow from the quiddity itself like the “evenness” of the number four. Another way of explicating the difference is that the quiddity of x can be conceived without a concomitant ofexistence, but it cannot be conceived without the concomitant ofquiddity.¹⁴

After summarizing the philosophers’ views, Ibn Taymiyya proceeds to show that these categorizations are ill-founded, as they rest on two flawed metaphysical distinctions—namely: (1) the distinction between quiddity and its existence, and (2) the distinction between what is essential to quiddity (al-dhātī lahā) and what is concomitant to quiddity (al-lāzim lahā). We will discuss them in turn.

5.1 Quiddity and its Existence

The first metaphysical doctrine of the logicians that Ibn Taymiyya complains about is the distinction between quiddity and its existence. For Ibn Taymiyya, quiddity is meant to answer the question “what is it?”, and this is clearly a mental category. For him, it is not clear how quiddities can have a stable existence in extramental substances if the way we approach the question is mental (and linguistic) by nature. In that sense, he rejects the philosophers’ claim that quiddity has a stable truth “other than its own existence.”

Indeed, the root of their [i.e. the philosophers] misguidance is that they observed how a thing—prior to its actual existence—can nonetheless be known, willed…Hence, they said: ‘Were it not extra-mental, it could not be like that.’…Thus arises the mistaken assumption that these realities and quiddities are actual entities subsisting in external reality. Yet upon closer examination, it becomes clear that all of these matters reside only in the mind and have no real existence outside of it.” [24, p. 106; emphasis is mine]

Here Ibn Taymiyya is responding more to the Peripatetic tradition, especially those influenced by Ibn Sīnā (Avicenna), than to Aristotle himself. The core belief that Ibn Taymiyya rejects is the distinction between quiddity qua quiddity and its ontological status. Ibn Sīnā’s position is unlike that of the Latin scholastic realists but more of a qualified form of realism. For Ibn Sīnā, a pure quiddity is neither a mental category nor a Platonic form, nor is it identical to concrete individuals. But it has a unique ontological status between the mental and extra-mental—it exists only when the form and matter get attached to it.¹⁵ Ibn Taymiyya objects to this as he thinks that there are only two modes of existence: in the mind and the world: “The correct distinction is that quiddity is what is imprinted in the mind of a thing, whereas existence (al-wujūd) is what is present externally.” [24, p. 109]

To showcase this point—that quiddity is a mental construct and does not necessarily correspond to any extra-mental existence—he runs a skeptical argument from conceivability: If quiddity refers to the “complete concept” that is stable and extra-mental in the world (as claimed), then it would not be possible to conceive of it without its essential properties. Nonetheless, Ibn Taymiyya points out that this is not the case. For instance, if the quiddity of “humanity” corresponds to an external existence “humanity”, then there should be no disagreement on the quiddity of say “humans”. Yet, one can conceive the quiddity of a human as “rational animal”, and another person could conceive it as a “laughing animal”, a reductio [24, pp. 109–110]. Then Ibn Taymiyya, entertains the following objection to his conceivability argument:

If it is said: They intend by this what Ibn Sīnā and others mentioned—that “number” is even or odd not as a distinct description for each number, but rather as something known of number itself without any mediation (bilā wasṭ), just as one knows that “two” is the half of “four,” and in other instances one may not know that except through mediation like knowing that “one thousand three hundred seventy two” has a half. Different from this, knowing that “animality” belongs to “animal” is obvious without any mediation [24, p. 110; emphasis is mine].

Hence, this potential objection relies on some connection between the ability of the cognizer to conceive that essential predicates belong to the quiddity without mediation, while non-essential ones need some form of mediation (e.g. reasoning or an intermediary proposition). Ibn Taymiyya responds by showing two flaws here. The first is that the philosophers conflate between the manner in which a relation is known and the relation itself. So, whether an attribute is apprehended immediately or through a mediate form pertains to the capacity of human cognition and not to the thing-in-itself. Immediate knowledge (‘ilm bilā wasṭ) is not isomorphic to immediate metaphysical connection (thubūt bilā wasṭ). The former is epistemic (i.e. pertains to the mind’s ability to order relations), while the latter is ontological (i.e., pertains to the metaphysical order of the properties themselves). The confusion stems from the usage of language to bridge the gap between the epistemic and the ontic, so it would appear as if they were the same.

The second flaw is that even if we assume that there is an isomorphism between the cognition of predicates and quiddity, it appears that this connection is contingent on the subject’s cognitive abilities and prior knowledge of the subject [24, p. 111]. For example, it might take a considerable deliberation from someone to realize that 523 is a prime number, while this is obvious for a number theorist due to their acquaintance with the subject. But this would mean that a predication could be both essential and non-essential for a quiddity—a reductio. In this way, Ibn Taymiyya argues that what the philosophers have presented as an ontological distinction between quiddity and its existence collapses, at best, into an epistemological and/or semantic contingency.

Before continuing Ibn Taymiyya’s line of reasoning, it is worth noting that al-Ghazālī—well before Ibn Taymiyya—offered a similar critique, arguing that it is pragmatically difficult to construct a definition in the genus–differentia sense due to comparable problems. In The Standard Measure of Knowledge (Mi‘yār al-‘Ilm), al-Ghazālī raises four pragmatic concerns, which I will discuss briefly.¹⁶ The first concern is the identification of the nearest genus. It is not always obvious what the correct closest genus is to the human mind, so a legal scholar could classify wine as “a prohibiting entity”, while the nearest genus is de facto a “drink”. The context of epistemic inquiry influences this process, which is a pragmatic challenge.

The second concern is the possibility of human error in mixing essential and accidental properties. Al-Ghazālī stresses that: “…but how does one ensure that the chosen differentia is not merely accidental (‘araḍī)?” There is no guarantee; especially when compounded with the first aforementioned challenge. The third challenge is the problem of universality in differentia (faṣl kullī). Similar to the first concern, “how can one guarantee that no part of the differentia is missing or that no broader characteristic has been wrongly included?” Again, this is a pragmatic challenge because while it may be true that there is an objective way of achieving a universal differentia for each definition, it does not seem cognitively feasible even regarding simple definitions like “horse”.

Finally, al-Ghazālī stresses another pragmatic challenge in the genusspecies hierarchical division (taqsīm al-naw‘ī wa’l-jinsī). Namely, the pragmatic failure of distinguishing between genus-based (jinsī) and differentia-based (faṣlī) divisions. He argues that one should prioritize differentia-based divisions but still most theoreticians err in this regard. He states, “Example: The term ‘body’ is divided into growing and non-growing. This division assumes a genus-level distinction, rather than a proper differentia-based distinction.” But this not merely an epistemic error, rather it is a cognitive challenge, as “prioritization in classification is a necessary condition for proper logical definition, yet it remains extremely difficult to perfect.”

To sum up the previous discussion, Ibn Taymiyya argues that the philosophers’ supposed distinction between quiddity and its existence ultimately collapses into an epistemological and/or semantic difference. Now, we can resume the second source of the philosophers’ errors, namely the distinction between what is essential to quiddity (al-dhātī lahā) and what is concomitant to quiddity (al-lāzim lahā)

5.2 On the difference between what is essential to quiddity and what is concomitant to quiddity

Recall that Ibn Taymiyya reported the difference as follows: what is essential to quiddity is internal to its metaphysical nature, while what is concomitant to quiddity follows from its metaphysical nature (i.e. it is external to it but still follows by necessity), like “evenness” for number four. One could conceive the property “being the successor of three and the predecessor of five” as an essential predicate of the quiddity of four. Yet “evenness” or “divisibility by two” follows necessarily from the nature of four but is not part of its quiddity. This differentiation was common in the post-classical period. As mentioned earlier, one way of distinguishing between these two types of predicates is through the conceivability test: if property p is essential to quiddity Q, it is impossible to conceive Q without p; by contrast, if p is concomitant to Q, it is possible to conceive Q without p. In a similar vein to what he did in the previous section, Ibn Taymiyya pushes back against this conceivability test:

And when it is said: ‘It is possible for “four” or “three” to occur to one’s mind such that one understands it without entertaining whether that is a “number,” whether even or odd.’ One might reply: ‘Likewise, it is possible for “human” to occur to someone’s mind without his ever reflecting on the fact that he is “rational” or “animal”. Then, if the objection is raised: ‘That would not be a complete conception for human,’ it can be answered: ‘Neither would that be a complete conception of “four” or “three.” [24, p. 112]

He attributes the fact that different conceivers can cognize what is essential about a “human” differently to the differences in their intellectual abilities [24, p. 113]. What is essential, and what is concomitant is purely relative to the cognizer and not an extra-mental property of quiddity. More specifically, he presses two points against the essential-concomitant distinction.

First, and based on the previous arguments, Ibn Taymiyya thinks that essential predication is not ontologically prior to concomitant predication. So, why would most philosophers say that “rationality” is ontologically prior to “laughter” for the quiddity “human”? His answer is that this is purely an arbitrary imposition (taḥakkum maḥḍ) that was historically generated through some linguistic and pedagogical habits. In some sense, philosophers get trained to think in this specific way without questioning their tradition. Hence, a person following Aristotelian logicians would think that a concept that is purely invented (takhtari’) corresponds to a natural thing in the world.

The second point that he pushes against is the following:

They [the philosophers] especially say that the essential precedes the quiddity both in the mind and in external reality, and they call it “the constitutive part of it” (al-juz’ al-muqawwim lahā). They also say that the parts of the quiddity are prior to it both conceptually and externally, since the quiddity is composed of them—and everything composed is preceded by its components. [24, p. 113]

Ibn Taymiyya considers this to be an implication of the essential–concomitant distinction. But again, he argues that this results from conceptual and linguistic confusions. When conceiving something, one cannot grasp its totality all at once but must instead conceive or articulate its various essential predicates sequentially. He gives the following example [24, p. 114], when we say a “body that is sentient, growing, moving by will, and speaking,” to describe a “living body” we utter these predicates in a sequence that can create the impression that one precedes the other. But this is just an illusion due to the temporal structure of thought–language. The priority of essential predicates reflects a compositionality in linguistic structures, and not metaphysical relations. Consequently, a quiddity is preceded by its parts only in thought–language, not in re.

Interestingly, al-Rāzī offers a slightly different criticism (i.e. more on the logical side) of the essential–concomitant to quiddity distinction. He writes in al-Muḥaṣṣal,

…defining the quiddity of a thing must either be by itself (bi-nafsihā), by something within it (dākhil fīhā), or by something external to it (khārij ‘anhā). Alternatively, it may be written from either of the last two options [11, p. 7]

Then, al-Rāzī refutes the three possibilities. Firstly, and trivially, the first option is circular. The second option (i.e. defining quiddity by something within it) is also circular.¹⁷ Here is why: Let Q be defined as D($Q)=${a, b, c}, if {a, b, c}  are essential predicates of Q, then there is no extra information generated by the definition, as both, the definiens and the definiendum are analytically equivalent, and hence the circularity.¹⁸ The third option is not viable either as it leads to regress. Why? “…  because different quiddities (māhiyyāt mukhtalifah) do not necessarily share a single necessary condition.” If so, then quiddities can only form relational definitions, like defining Q relative to something else Z rather than explaining what Q is in itself, ad infinitum.¹⁹

Returning to Ibn Taymiyya, he explicitly states [24, p. 114] that the supposed distinctions between “quiddity,” “that which is internal to it,” and “that which is external but concomitant with it” collapse into three kinds of mental–linguistic reference, respectively: (a) by correspondence (bi-l-muṭābaqah), (b) by implication (bi-l-taḍammun), and (c) by entailment (bi-l-iltizām). This mental–linguistic turn aims to establish the priority of the mental and linguistic over the metaphysical. In this way, the relation between parts and wholes, essence and concomitant, or genus and differentia have no extra-mental priority; it is a structure of the intellect and language. It is worth noting that Ibn Taymiyya is not always careful in distinguishing between thought and language, sometimes using them interchangeably as if they were isomorphic. This has led many interpreters to regard his critique of Aristotelian metaphysics as the epitome of Islamicate nominalism—a claim to be examined in the final two sections

6 Was Ibn Taymiyya a Nominalist?

Given the preceding discussion, the question arises: was Ibn Taymiyya a nominalist? Many commentators give a positive answer.²⁰ Nominalism has many variations, but if we take a minimal thesis it would be something like this: there exists no universals,²¹ and instead all entities are either particulars or individuals.²² In other words, there are no separate metaphysical entities (regardless of their nature) that are responsible for the qualitative differences (e.g. variations and sameness) of particular objects. We already saw that Ibn Taymiyya denies the distinction between quiddities and their existence, and consequently quiddities cannot exist prior to the existence of particulars. This general position could possibly qualify him as a nominalist. Even though, some would consider that these tendencies could be more leaning towards empiricism. For instance, [20] argued that Ibn Taymiyya was foreshadowing British empiricists in many of their doctrines: basing knowledge on inductive reasoning, deriving basic mathematical axioms from particulars, his emphasis on the primacy of sense perception over reason, among others. Upon closer scrutiny, however, it appears that Ibn Taymiyya was neither a nominalist nor an empiricist per se. While he certainly shared some features with both doctrines, as discussed earlier, one cannot ascribe to him a fully developed form of either nominalism or empiricism.

Regarding nominalism, merely rejecting universals as separate entities is not sufficient to qualify one as a nominalist. A more developed philosophical position on the nature of the mind and its relation to other entities is required—take, for instance, Ockham’s fictum theory, in which universals are conceived as mental fictions, or his later intellectio theory, where universals are not mental objects but rather mental acts. Yet, Ibn Taymiyya in The Refutation does not attempt to develop such a theory for reasons we will discuss later.²³ As for empiricism, he is not an empiricist either as he considers a variety of epistemic sources that would be immediately discarded by empiricists like revelation, testimony, and others.²⁴

Another proposed interpretation of Ibn Taymiyya’s position is conventionalism.²⁵ [38] argues that Ibn Taymiyya revived the grammarians’ approach (e.g. Abu Sa’id al-Sirafi (d. 979)) to logic that is based on the dependency of thought on language. For someone like al-Sirafi, Greek logic does not reflect anything beyond the contingencies of linguistic conventions that were developed over time. Indeed, there are many passages in The Refutation where Ibn Taymiyya refers to the role of conventions in the formation of definitions, but this cannot be taken as full-blown conventionalism. Why? Because canonical versions of conventionalism,²⁶ especially in metaphysics, logic and epistemology, take conceptual schemes to be primarily shaped through some form of convention like when Poincaré argues that geometric axioms are disguised definitions. In that sense, there are no factual truth-makers—say, about space—that can render a geometric axiom true or false. Nevertheless, we already saw that this is not what Ibn Taymiyya aims for when arguing against definitions. For instance, he believes that it is possible to conceive the nature of entities using sense perceptions without resorting to definitions [24, p. 53]. In fact, he openly criticizes that conventions can generate knowledge:

As for those conventions that contradict the plain dictates of reason and existence, they are false, even if they are mere conventions. For if our criterion (mīzānunā) for the sciences and realities were to depend on conventions and terminologies, then true scientific realities would differ with every change of terminology and convention — but they do not. Rather, the genuine scientific realities do not vary with differing conventions and terms, such as knowing the attributes and realities of things. [24, p. 68; emphasis is mine]

This position is distinct from the standard doctrines of conventionalism. There may be more refined versions of conventionalism capable of accommodating this view, but I will not pursue them here. For now, and given Ibn Taymiyya’s arguments so far, I would claim that his closet position when it comes to the nature of definitions (and language in general) is pragmatics, and I will try to briefly argue for this in the coming section.

7 Ibn Taymiyya’s Pragmatics

My aim in this section is to argue that the position most closely explaining Ibn Taymiyya’s criticisms is pragmatics. I will not attempt to develop a complete case for this, as it would require a separate paper; rather, my goal here is to lay the groundwork for such an argument. As [28] explain, the main difference between pragmatics and semantics lies in their respective focuses: semantics is primarily concerned with analyzing the conventional rules that generate linguistic meaning, whereas pragmatics is more versatile, extending beyond the semantic content conventionally encoded in words to include context, speaker intention, and use. In the most general sense, pragmatics involves dealing with non-linguistic facts that can reveal the hidden meaning of a linguistic expression. These facts could include: a) facts about the utterance itself (who, when and where), b) facts about the intentions of the speaker(s), c) facts about the epistemic context of the speaker(s) (their beliefs, the goal of the conversation, etc.), and d) facts about the social institutions that are relevant to the utterance (a thesis defense, a political debate, etc.). This diversity of sources gives pragmatics an explanatory power when analyzing linguistic utterances, and especially definitions.

First recall that Aristotle vividly distinguishes between naming and defining. In the Posterior Analytics, (2, 92, 25–30), he writes:

Since, therefore, to define is to prove either a thing’s essential nature or the meaning of its name, we may conclude that definition, if it in no sense proves essential nature, is a set of words signifying precisely what a name signifies. But that is a strange consequence, for both what is not substance and what does not exist at all would be definable.

Hence, a definition would reveal the quiddity of the object, only if it exists; but naming would be signifying a thing, whether it exists or not. By virtue of rejecting the Aristotelian conceptions of genus, differentia, and quiddity, Ibn Taymiyyah ends up discarding the distinction between defining and naming.

…the purpose of definition is to distinguish the defined thing from what is other than it — just as the purpose of a name is the same. Its function, then, is not to “present the form of the defined thing and to disclose its true reality.” [24, p. 56; emphasis is mine]

He observes that when someone defines something, they do not necessarily possess correct knowledge of the quiddity of the definiendum. In pragmatic terms, the purpose of the speech act of “defining” is, rather, akin to that of “naming”— that is, to differentiate the definiendum (or nominatum) in a clear way.²⁷ Put differently, the conceptual relation between the definiens and the definiendum is isomorphic to the relation between the signifier and the signified at the pragmatic level.²⁸ Additionally, Ibn Taymiyyah is also open to more functions that a definition can play in speech acts other than naming, and this is where his pragmatics dimension kicks in.

…A definition is sometimes formulated with respect to the name, and at other times with respect to the thing named …likewise …a definition is sometimes given with respect to the name of the thing, and at other times with respect to its reality (ḥaqīqah). If the definition pertains to the name, it may or may not correspond to the extra-mental reality (al-khārij). Yet the intended meaning here is that a definition sometimes differentiates between the various meanings of a word and sometimes between extra-mental entities. Such differentiation arises through the definition.

Consequently, a definition can operate on three distinct levels: (a) at the semantic level, by naming things through a word–word relation; (b) at the metaphysical level, by referring to the thing in itself through a word–object relation; and (c) at the mental level, by referring to mental ideas through a word–thought relation. In all these cases, a definition aims to differentiate between semantic, mental, or metaphysical objects, and it may or may not refer to their essences, depending on context.

Another connection between the speech acts of naming and defining is that both serve to direct the mind toward conceiving the definiendum (or nominatum). This process of conceptualization may be mistaken in grasping the reality of the definiendum, yet its true epistemic value lies in transforming the definiendum into an intentional object for the speaker.²⁹

Given that, the question now arises: how do definitions acquire meaning in the first place, if they neither describe essences nor rest on mere conventions? Here Ibn Taymiyya does not offer a set of determining criteria for the semantics of definitions, instead, he draws on various pragmatic sources. For instance, he holds that definitions are meaningful only within a complex network of factors that enable communication between speaker and hearer—such as sense experience, established conventions, linguistic norms, natural regularities, and the speaker’s intentions, among others. These criteria make definitions (and language in general) intelligible, but not objectively stable across contexts. A large part of this instability is due to the subjective intentional (maqaṣed) nature of ascribing specific properties to different objects at different times, which gets reflected and translated into definitions. Interestingly, this point foretells Locke’s, and other British empiricists, claim that properties are neither essential nor accidental, but can only be classified according to the subjective interest of the classifier.³⁰ Here is a toy example: Imagine a society where material objects are classified according to their quotidian functions, and not by their geometric shapes or materials. In this society, there are no objects named “cup” or “bowl”. Instead, we have a “drinkel”: an object used for drinking, and a “soupel”: an object used for eating soup. Thus, a single ceramic vessel can be both a drinkel and soupel at the same time depending on usage. But “a change in function” is usually regarded as non-essential property by many as a bowl would still be a bowl even if I use it to have my morning cortado. Ibn Taymiyya thus argues that what constitutes the genus-differentia of an object, then, is not inherent in the object’s physical composition but determined by human practical interests, usage, and intentions. Subsequently, what the philosophers include or exclude as part of the genus is highly contextual, for Ibn Taymiyya, implying a sense of arbitrariness.³¹

Finally, part of Ibn Taymiyya’s pragmatics in countering the philosophers’ theory of definition is to classify the different types of definitions and to show that, in most cases, definitions do not aim to capture the real essence of the definiendum. Rather, they serve contextual, linguistic, or demonstrative purposes. He identifies at least four kinds of definitions [24, p. 93]:

a. Lexical definition (ḥadd ḥasab al-ism): aims to specify the linguistic meaning of the word as conventionally practiced.

b. Semantically equivalent definition: this involves substituting the definiendum with a synonymous expression that conveys the same meaning, such as replacing one linguistic sign with another of identical sense.

c. Descriptive definition: this employs a non-synonymous but extensionally equivalent expression—that is, one that refers to the same object. For example, the term ṣārim (sharp sword) may be defined as muhannad (Indian-made sword). The two are not semantically equivalent but denote the same referent in the world.

d. Ostensive definition: this kind of definition functions through direct demonstration, such as when one points to an object and says “this!” (hādhā)—for instance, when identifying a loaf of bread for someone unfamiliar with the word.

To sum up, I have argued so far, in this section, for a reading of Ibn Taymiyya’s pragmatics that situates his critique of definition within a broader theory of meaning grounded in use, intention, and context. This has been shown primarily through his conception of definitions as speech acts that serve multiple communicative purposes rather than as instruments of metaphysical disclosure.

8 Conclusion

This paper has examined Ibn Taymiyya’s critique of the Aristotelian theory of definition as articulated in The Refutation of the Logicians, situating it within its broader Islamicate intellectual context. We explored two kinds of criticisms that were developed through out the book: a list of general criticisms, and two specific metaphysical criticisms. Ibn Taymiyya’sgeneral criticisms undermined the epistemic value of Aristotelian definitions through multiple dialectical arguments from regress, disagreement, sense perception, redundancy, and others. The general goal was to show that the notion of definition is either inconsistent, circular or not epistemically useful (at least not in the way claimed by the logicians). His metaphysical criticisms targeted the very foundations of Peripatetic metaphysics, particularly the distinctions between quiddity and its existence, and between essential and concomitant predicates. Interestingly, Ibn Taymiyya’s overall approach in criticizing the philosophers’ positions relies on dialectical methods aimed at deconstructing metaphysical speculations about the essential and accidental nature of quiddities. By collapsing these distinctions into mental–linguistic relations—Ibn Taymiyya aimed to reframe metaphysical categories as products of the intellect and language rather than extramental relations.

I have also argued that Ibn Taymiyya’s position cannot be reduced to nominalism, empiricism, or conventionalism. Rather, his theory of meaning is closer to modern pragmatics, wherein speech acts derive their meaning from their communicative, intentional, and contextual functions. By establishing a metaphysically-thin theory of definition that can be grounded in pragmatics, a definition ceases to be a mirror of metaphysical essences and becomes instead a mode of human interaction—a way of differentiating, naming, referring, etc. Later in The Refutation, Ibn Taymiyya resumes his critique of the logical corpus by debunking the notion of syllogistic reasoning. By refuting the two cornerstones of a logical system: the notions of definition and categorical syllogism, Ibn Taymiyya argues that this opens the way for alternative epistemic sources— such as sense perception (tajriba), intuition (ḥads), mass testimonial transmission (tawātur) — that can generate certain knowledge aside from demonstrative reasoning [24, p. 133].