This edited volume of 13 new essays aims to turn past discussions of natural kinds on their head. Instead of presenting a metaphysical view of kinds based largely on an unempirical vantage point, it pursues questions of kindedness which take the use of kinds and activities of kinding in practice as significant in the articulation of them as kinds. The book brings philosophical study of current and historical episodes and case studies from various scientific disciplines to bear on natural kinds (...) as traditionally conceived of within metaphysics. Focusing on these practices reveals the different knowledge-producing activities of kinding and processes involved in natural kind use, generation, and discovery. -/- Specialists in their field, the esteemed group of contributors use diverse empirically responsive approaches to explore the nature of kindhood. This groundbreaking volume presents detailed case studies that exemplify kinding in use. Newly written for this volume, each chapter engages with the activities of kinding across a variety of disciplines. Chapter topics include the nature of kinds, kindhood, kinding, and kind-making in linguistics, chemical classification, neuroscience, gene and protein classification, colour theory in applied mathematics, homology in comparative biology, sex and gender identity theory, memory research, race, extended cognition, symbolic algebra, cartography, and geographic information science. -/- The volume seeks to open up an as-yet unexplored area within the emerging field of philosophy of science in practice, and constitutes a valuable addition to the disciplines of philosophy and history of science, technology, engineering, and mathematics. -/- Contributions from a diverse group of established and junior scholars in the fields of Philosophy and History and Philosophy of Science including Hasok Chang, Jordi Cat, Sally Haslanger, Joyce C. Havstad, Catherine Kendig, Bernhard Nickel, Josipa Petrunic, Samuli Pöyhönen, Thomas A. C. Reydon, Quayshawn Spencer, Jackie Sullivan, Michael Wheeler, and Rasmus Grønfeldt Winther. (shrink)

Homeostatic property clusters (HPCs) are offered as a way of understanding natural kinds, especially biological species. I review the HPC approach and then discuss an objection by Ereshefsky and Matthen, to the effect that an HPC qua cluster seems ill-fitted as a description of a polymorphic species. The standard response by champions of the HPC approach is to say that all members of a polymorphic species have things in common, namely dispositions or conditional properties. I argue that this response fails. (...) Instances of an HPC kind need not all be similar in their exhibited properties. Instead, HPCs should instead be understood as unified by the underlying causal mechanism that maintains them. The causal mechanism can both produce and explain some systematic differences between a kind’s members. An HPC kind is best understood not as a single cluster of properties maintained in stasis by causal forces, but as a complex of related property clusters kept in relation by an underlying causal process. This approach requires recognizing that taxonomic systems serve both explanatory and inductive purposes. (shrink)

Scientific Essentialism defends the view that the fundamental laws of nature depend on the essential properties of the things on which they are said to operate, and are therefore not independent of them. These laws are not imposed upon the world by God, the forces of nature, or anything else, but rather are immanent in the world. Ellis argues that ours is a dynamic world consisting of more or less transient objects that are constantly interacting with each other, and whose (...) identities depend on their roles in these processes. The laws of nature are metaphysically necessary, and consequently, there are necessary connections between events. (shrink)

I aim to reconcile two apparently conflicting theses: (a) Everything that can be explained, can be explained in purely physical terms, that is, using the machinery of fundamental physics, and (b) some properties that play an explanatory role in the higher level sciences are irreducible in the strong sense that they are physically undefinable: their nature cannot be described using the vocabulary of physics. I investigate the contribution that physically undefinable properties typically make to explanations in the high-level sciences, and (...) I show that when they are explanatorily relevant, it is in virtue of their extension (or something close) alone. They are irreducible because physics cannot capture their nature; this is no obstacle, however, to physics' more or less capturing their extension, which is all that it need do to duplicate their explanatory power. In the course of the argument, I sketch the outlines of an account of the explanation of physically contingent regularities, such as the regularities found in most branches of biological inquiry, at the center of which is an account of the nature of contingent, empirical bridge principles. (shrink)

Homeostatic Property Cluster (HPC) theory suggests that species and other biological taxa consist of organisms that share certain similarities. HPC theory acknowledges the existence of Darwinian variation within biological taxa. The claim is that “homeostatic mechanisms” acting on the members of such taxa nonetheless ensure a significant cluster of similarities. The HPC theorist’s focus on individual similarities is inadequate to account for stable polymorphism within taxa, and fails properly to capture their historical nature. A better approach is to treat distributions (...) of traits in species populations as irreducible facts, explained in terms of selection pressures, genealogy, and other evolutionary factors. We call this view Population Structure Theory (PST). PST accommodates the view, implicit in biological systematics, that species are identified by reference to particular historical populations. (shrink)

Causation is important. It is, as Hume said, the cement of the universe, and lies at the heart of our conceptual structure. Causation is one of the most fundamental tools we have for organizing our apprehension of the external world and ourselves. But philosophers' disagreement about the correct interpretation of causation is as limitless as their agreement about its importance. The history of attempts to elucidate the nature of this concept and to situate it with respect to other fundamental concepts (...) is almost as long as the history of philosophy itself. In this first English translation of Causalite; et lois de la nature Max Kistler seeks to reconstruct a unified concept of causation that is general enough to adequately deal with both elementary physical processes and the macroscopic level of phenomena we encounter in everyday life. It will be of great interest to philosophers of science and metaphysics; and also to students and scholars of philosophy of mind where concepts of causation and law play a prominent role. (shrink)

Scientists may sometimes generalize from their samples to broader populations when they have not yet sufficiently supported this generalization. Do such hasty generalizations also occur in experimental philosophy? To check, we analyzed 171 experimental philosophy studies published between 2017 and 2023. We found that most studies tested only Western populations but generalized beyond them without justification. There was also no evidence that studies with broader conclusions had larger, more diverse samples, but they nonetheless had higher citation impact. Our analyses reveal (...) important methodological limitations of many experimental philosophy studies and suggest that philosophical training may not protect against hasty generalizations. (shrink)

Generic generalisations like ‘Opioids are highly addictive’ are very useful in scientific communication, but they can often be interpreted in many different ways. Although this is not a problem when all interpretations provide the same answer to the question under discussion, a problem arises when a generic generalisation is used to answer a question other than that originally intended. In such cases, some interpretations of the generalisation might answer the question in a way that the original speaker would not endorse. (...) Rather than excising generic generalisations from scientific communication, I recommend that scientific communicators carefully consider the kinds of questions their words might be taken to answer and try to avoid phrasing that might be taken to provide unintended answers. (shrink)

We are often justified in acting on the basis of evidential confirmation. I argue that such evidence supports belief in non-quantificational generic generalizations, rather than universally quantified generalizations. I show how this account supports, rather than undermines, a Bayesian account of confirmation. Induction from confirming instances of a generalization to belief in the corresponding generic is part of a reasoning instinct that is typically (but not always) correct, and allows us to approximate the predictions that formal epistemology would make.

Recent years have seen renewed interest in the semantics of generics. And a relatively mainstream view in this work is that the semantics of generics must appeal to kinds. But what are kinds? Can we learn anything about their nature by looking at how semantic theories of generics appeal to them? In this article, we overview recent work on the semantics of generics and consider their consequences for our understanding of the metaphysics of kinds.

Natural kinds is a widely used and pivotal concept in philosophy – the idea being that the classifications and taxonomies employed by science correspond to the real kinds in nature. Natural kinds are often opposed to the idea of kinds in the human and social sciences, which are typically seen as social constructions, characterised by changing norms and resisting scientific reduction. Yet human beings are also a subject of scientific study.Does this mean humans fall into corresponding kinds of their own? (...) In The Epistemology and Morality of Human Kinds Marion Godman defends the idea of human kinds. She first examines the scientific use and nature of human kinds, considering the arguments of key philosophers whose work bears upon human kinds, such as Ian Hacking, John Searle, Richard Boyd and Ruth Millikan. Using the examples of gender, ethnic minorities and Buddhism she then argues that human kinds are a result of ongoing historical reproduction, chiefly due to pre-existing cultural models and social learning. Her novel argument shifts the focus away from the reductionism characteristic of research about human kinds. Instead, she argues that they are “multiply projectable” and deserving of scientific study not in spite of, but because of their role in explaining our identity, injustice and the emergence of group rights. (shrink)

Moderate pluralism is a popular position in contemporary philosophy of biology. Despite its popularity, various authors have argued that it tends to slide off off into a radical form of pluralism that is both normatively and descriptively ueptable. This paper looks at at the case of biological species classification, and evaluates a popular way of avoiding radical pluralism by relying on the shared aims and norms of a discipline. The main contention is that while these aims and norms may play (...) an important role in the legitimacy of species classifications, they fail to fend off radical pluralism. It follows from this that the legitimacy of species classifications is also determined by local decisions about the aims of research and how to operationalize and balance these. This is important, I argue, because it means that any acceptable view on the legitimacy of classification should be able to account for these local decisions. (shrink)

Bernhard Nickel presents a theory of generic sentences and the kind-directed modes of thought they express. The theory closely integrates compositional semantics with metaphysics to solve the problem that generics pose: what do generics mean? Generic sentences are extremely simple, yet if there are patterns to be discerned in terms of which are true and which are false, these patterns are subtle and complex. Ravens are black, and lions have manes: statistical measures cannot do justice to the facts, but what (...) else is there that has a hope of giving us insight into what we are capturing across so many domains? Nickel argues that generics are the top of a fundamentally explanatory iceberg, and that this explanatory framework is deeply intertwined with the semantics of the language we use to express them. In providing an integrated semantic and metaphysical theory of generics, he aims to solve old puzzles and draw attention to new phenomena. (shrink)

Scientific Essentialism defends the view that the fundamental laws of nature depend on the essential properties of the things on which they are said to operate, and are therefore not independent of them. These laws are not imposed upon the world by God, the forces of nature or anything else, but rather are immanent in the world. Ellis argues that ours is a dynamic world consisting of more or less transient objects which are constantly interacting with each other, and whose (...) identities depend on their roles in these processes. Natural objects must behave as they do, because to do otherwise would be contrary to their natures. The laws of nature are, therefore, metaphysically necessary, and consequently, there are necessary connections between events. Brian Ellis calls for the rejection of the theory of Humean Supervenience and an implementation of a new kind of realism in philosophical analysis. (shrink)

The notion of 'natural kinds' has been central to contemporary discussions of metaphysics and philosophy of science. Although explicitly articulated by nineteenth-century philosophers like Mill, Whewell and Venn, it has a much older history dating back to Plato and Aristotle. In recent years, essentialism has been the dominant account of natural kinds among philosophers, but the essentialist view has encountered resistance, especially among naturalist metaphysicians and philosophers of science. Informed by detailed examination of classification in the natural and social sciences, (...) this book argues against essentialism and for a naturalist account of natural kinds. By looking at case studies drawn from diverse scientific disciplines, from fluid mechanics to virology and polymer science to psychiatry, the author argues that natural kinds are nodes in causal networks. On the basis of this account, he maintains that there can be natural kinds in the social sciences as well as the natural sciences. (shrink)

Homology is a natural kind concept, but one that has been notoriously elusive to pin down. There has been sustained debate over the nature of correspondence and the units of comparison. But this continued debate over its meaning has focused on defining homology rather than on its use in practice. The aim of this chapter is to concentrate on the practices of homologizing. I define “homologizing” to be a concept-in-use. Practices of homologizing are kinds of rule following, the satisfaction of (...) which demarcates a category—that of being a homologue. Identifying, explaining, discovering, and understanding are exchanges that connect practice to concept through the performance of a rule by practitioners. These practices are constitutive of natural kinding activities. If homologizing is a kind of kinding, consideration of these practices of discovery, tracking, and identification not only clarifies the meaning, use, and progression of the concept of homology, but provides further understanding of the processes and progression of natural kinds and kinding practices in general. (shrink)

Innate cognitive capacities are widely posited in cognitive science, yet both philosophers and scientists have criticized the concept of innateness as being hopelessly confused. Despite a number of recent attempts to define or characterize innateness, critics have charged that it is associated with a diverse set of properties and encourages unwarranted inferences among properties that are frequently unrelated. This criticism can be countered by showing that the properties associated with innateness cluster together in reliable ways, at least in the context (...) of the study of cognition. Even though the causal connections between these cognitive properties are not always strict, they are robust enough to warrant considering innateness to be a natural kind as used in contemporary cognitive science. (shrink)

In the first controlled, non-self-report studies to show an influence of university-level ethical instruction on everyday behavior, Schwitzgebel et al. (2020) and Jalil et al. (2020) found that students purchase less meat after exposure to material on the ethics of eating meat. We sought to extend and conceptually replicate this research. Seven hundred thirty students in three large philosophy classes read James Rachels’ (2004) “Basic Argument for Vegetarianism”, followed by 50-min small-group discussions. Half also viewed a vegetarianism advocacy video containing (...) factory farm footage. A few days after instruction, 54% of students agreed that “eating the meat of factory farmed animals is unethical”, compared to 37% before instruction, with no difference between the film and non-film conditions. Also, 39% of students anonymously pledged to avoid eating factory farmed meat for 24 h, again with no statistically detectable difference between conditions. Finally, we obtained 2828 campus food purchase receipts for 113 of the enrolled students who used their Student ID cards for purchases on campus, which we compared with 5033 purchases from a group of 226 students who did not receive the instruction. Meat purchases remained constant in the comparison group and declined among the students exposed to the material, falling from 30% to 23% of purchases overall and from 51% to 42% of purchases of $4.99 or more, with the effect possibly larger in the film condition. (shrink)

In the first controlled, non-self-report studies to show an influence of university-level ethical instruction on everyday behavior, Schwitzgebel et al. (2020) and Jalil et al. (2020) found that students purchase less meat after exposure to material on the ethics of eating meat. We sought to extend and conceptually replicate this research. Seven hundred thirty students in three large philosophy classes read James Rachels’ (2004) “Basic Argument for Vegetarianism”, followed by 50-min small-group discussions. Half also viewed a vegetarianism advocacy video containing (...) factory farm footage. A few days after instruction, 54% of students agreed that “eating the meat of factory farmed animals is unethical”, compared to 37% before instruction, with no difference between the film and non-film conditions. Also, 39% of students anonymously pledged to avoid eating factory farmed meat for 24 h, again with no statistically detectable difference between conditions. Finally, we obtained 2828 campus food purchase receipts for 113 of the enrolled students who used their Student ID cards for purchases on campus, which we compared with 5033 purchases from a group of 226 students who did not receive the instruction. Meat purchases remained constant in the comparison group and declined among the students exposed to the material, falling from 30% to 23% of purchases overall and from 51% to 42% of purchases of $4.99 or more, with the effect possibly larger in the film condition. (shrink)

This paper investigates the interaction between semantic theories for cp-laws (roughly, laws that hold “all things equal”) and metaphysical theories of kinds in the special sciences. Its central conclusion is that cp-laws concerning kinds behave differently from cp-laws concerning non-kinds: “ravens are black” which concerns the kind corvus corax, behaves differently from from “albino ravens are white” which concerns the non-kind grouping of albino ravens. I argue that this difference is in the first instance logical: the two sorts of cp-laws (...) give rise to different inferential patterns. I draw two further conclusions. The difference in logical behavior poses a severe problem for extant semantic theories of cp-laws, and: we cannot elucidate the distinction between kinds and non-kinds by suggesting that only kinds can appear in laws. (shrink)

What are species? Are they objective features of the world? If so, what sort of features are they? Do everyday intuitions that species are real stand up to philosophical and scientific scrutiny? Two rival accounts of species' reality have dominated the discussion: that species are natural kinds defined by essential properties and that species are individuals. Unfortunately, neither account fully accommodates biological practice. In Are Species Real?, Slater presents a novel approach to this question aimed at accommodating the attractions to (...) both realism and antirealism about species. (shrink)

Consensus has it that generic sentences such as “Dogs bark” and “Birds fly” contain, at the level of logical form, an unpronounced generic operator: Gen. On this view, generics have a tripartite structure similar to overtly quantified sentences such as “Most dogs bark” and “Typically, birds fly”. I argue that Gen doesn’t exist and that generics have a simple bipartite structure on par with ordinary atomic sentences such as “Homer is drinking”. On my view, the subject terms of generics are (...) kind-referring. The interesting truth conditions characteristic of generics arise from the interesting ways in which kinds inherit properties from their members. (shrink)

This is a study of a crucial and controversial topic in metaphysics and the philosophy of science: the status of the laws of nature. D. M. Armstrong works out clearly and in comprehensive detail a largely original view that laws are relations between properties or universals. The theory is continuous with the views on universals and more generally with the scientific realism that Professor Armstrong has advanced in earlier publications. He begins here by mounting an attack on the orthodox and (...) sceptical view deriving from Hume that laws assert no more than a regularity of coincidence between instances of properties. In doing so he presents what may become the definitive statement of the case against this position. Professor Armstrong then goes on to establish his own theory in a systematic manner defending it against the most likely objections, and extending both it and the related theory of universals to cover functional and statistical laws. This treatment of the subject is refreshingly concise and vivid: it will both stimulate vigorous professional debate and make an excellent student text. (shrink)

Natural kinds are often contrasted with other kinds of scientific kinds, especially functional kinds, because of a presumed categorical difference in explanatory value: supposedly, natural kinds can ground explanations, while other kinds of kinds cannot. I argue against this view of natural kinds by examining a particular type of explanation—mechanistic explanation—and showing that functional kinds do the same work there as traditionally recognized natural kinds are supposed to do in “standard” scientific explanations. Breaking down this categorical distinction between traditional natural (...) kinds and other kinds of kinds, I argue, delivers two goods: It provides us with a view of natural kindhood that does justice to the epistemic roles of kinds in scientific explanations. And it allows us to solve a problem that HPC theory, currently one of the more popular accounts of natural kindhood, confronts. (shrink)

In his _Between Logic and the World_, in the course of presenting his theory of generics, Nickel (Between logic and the world, Oxford University Press, 2016) argues for a theory of characteristicness, or “genericity”, which states that a property is characteristic for a kind if and only if its presence among the members of that kind is explicable by some explanatory domain that recognizes the existence of that kind in the course of engaging the explanatory strategies made available by that (...) explanatory domain. I argue that this notion of genericity is too narrow, excluding properties characteristic for kinds that go unrecognized in such explanatory domains. In particular, Nickel’s theory excludes some characteristic properties of anthropic kinds, such as lilies and cedars, members of which have properties that may be similarly exploited in various human practices despite having divergent geneses. I argue for a generalization of Nickel’s view of genericity where explicability of presence is only one sort of genericity, with others, such as practicability, being possible too. (shrink)

One primary goal for metaphysical theories of natural kinds is to account for their epistemic fruitfulness. According to cluster theories of natural kinds, this epistemic fruitfulness is grounded in the regular and stable co- occurrence of a broad set of properties. In this paper, I defend the view that such a cluster theory is insufficient to adequately account for the epistemic fruitfulness of kinds. I argue that cluster theories can indeed account for the projectibility of natural kinds, but not for (...) several other epistemic operations that natural kinds support. Natural kinds also play a role in scientific explanations and categorizations. A theory of natural kinds can only account for these additional kind-based epistemic practices if it also analyzes their causal structure. (shrink)

Natural kinds are often contrasted with other kinds of scientific kinds, especially functional kinds, because of a presumed categorical difference in explanatory value: supposedly, natural kinds can ground explanations, while other kinds of kinds cannot. I argue against this view of natural kinds by examining a particular type of explanation—mechanistic explanation—and showing that functional kinds do the same work there as traditionally recognized natural kinds are supposed to do in “standard” scientific explanations. Breaking down this categorical distinction between traditional natural (...) kinds and other kinds of kinds, I argue, delivers two goods: It provides us with a view of natural kindhood that does justice to the epistemic roles of kinds in scientific explanations. And it allows us to solve a problem that HPC theory, currently one of the more popular accounts of natural kindhood, confronts. (shrink)

Our knowledge about the world is often expressed by generic sentences, yet their meanings are far from clear. This book provides answers to central problems concerning generics: what do they mean? Which factors affect their interpretation? How can one reason with generics? Cohen proposes that the meanings of generics are probability judgments, and shows how this view accounts for many of their puzzling properties, including lawlikeness. Generics are evaluated with respect to alternatives. Cohen argues that alternatives are induced by the (...) kind as well as by the predicated property, and thus provides a uniform account of the varied interpretations of generics. He studies the formal properties of alternatives and provides a compositional account of their derivation by focus and presupposition. Cohen uses his semantics of generics to provide a formal characterization of adequate default reasoning, and proves some desirable results of this formalism. (shrink)

Behavioral scientists routinely publish broad claims about human psychology and behavior in the world's top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. Researchers – often implicitly – assume that either there is little variation across human populations, or that these “standard subjects” are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is (...) substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species – frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior – hence, there are no obviousa priorigrounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions ofhumannature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges. (shrink)

What do the words "ceteris paribus" add to a causal hypothesis, that is, to a generalization that is intended to articulate the consequences of a causal mechanism? One answer, which looks almost too good to be true, is that a ceteris paribus hedge restricts the scope of the hypothesis to those cases where nothing undermines, interferes with, or undoes the effect of the mechanism in question, even if the hypothesis's own formulator is otherwise unable to specify fully what might constitute (...) such undermining or interference. I will propose a semantics for causal generalizations according to which ceteris paribus hedges deliver on this promise, because the truth conditions for a causal generalization depend in part on the—perhaps unknown—nature of the mechanism whose consequences it is intended to describe. It follows that the truth conditions for causal hypotheses are typically opaque to the very scientists who formulate and test them. (shrink)

A large body of existing research suggests that people think very differently about categories that are seen as kinds (e.g., women) and categories that are not seen as kinds (e.g., people hanging out in the park right now). Drawing on work in linguistics, we suggest that people represent these two sorts of categories using fundamentally different representational formats. Categories that are not seen as kinds are simply represented as collections of individuals. By contrast, when it comes to kinds, people have (...) two distinct representations: a representation of a collection of individual people and a representation of the kind itself. The distinction between these two representational formats helps to shed light on otherwise puzzling findings about stereotyping and essentialism. Stereotyping appears to involve a representation of a collection of people, while essentialism involves a representation of a kind itself. (shrink)

Scientific realism is the view that our best scientific theories give approximately true descriptions of both observable and unobservable aspects of a mind-independent world. Debates between realists and their critics are at the very heart of the philosophy of science. Anjan Chakravartty traces the contemporary evolution of realism by examining the most promising strategies adopted by its proponents in response to the forceful challenges of antirealist sceptics, resulting in a positive proposal for scientific realism today. He examines the core principles (...) of the realist position, and sheds light on topics including the varieties of metaphysical commitment required, and the nature of the conflict between realism and its empiricist rivals. By illuminating the connections between realist interpretations of scientific knowledge and the metaphysical foundations supporting them, his book offers a compelling vision of how realism can provide an internally consistent and coherent account of scientific knowledge. (shrink)

Two ways of characterizing natural kinds are currently popular: the Kripke-Putnam appeal to microstructure and Boyd’s appeal to causal homeostasis. I argue that these conceptions are more divergent than is often acknowledged, that they give no credence to essentialism, and that they are both faulty. In their place, I sketch an alternative view of natural kinds, which I call “bare projectibilism”. This conception avoids the appeal to explanation common to microstructuralism and the causal homeostasis view, but is still compatible with (...) scientific realism. (shrink)

This article maintains that an important class of scientific generalizations should be reinterpreted: they have typically been understood as ceteris paribus laws, but are, in fact, generics. Four arguments are presented to support this thesis. One argument is that the interpretation in terms of ceteris paribus laws is a historical accident. The other three arguments draw on similarities between these generalizations and archetypal generics: they come with similar inferential commitments, they share a syntactic form, and the existing theories to make (...) sense of them are alike. Once these generalizations are properly understood as generics, the recent cognitive approach to generics can be extended to the study of the relevant sciences. The last section indicates ways in which this extension is fruitful for the two strands of research that we combine: the philosophy of science literature on generalizations and the semantics literature on generics. (shrink)