Spiders spin multiple types of silks that are renowned for their superb mechanical properties. Flagelliform silk, used in the capture spiral of an orb‐web, is one of the few silks characterized by both cDNA and genomic DNA data. This fibroin is composed of repeating ensembles of three types of amino acid sequence motifs. The predominant subrepeat, GPGGX, likely forms a β‐turn, and tandem arrays of these turns are thought to create β‐spirals. These spring‐like helices may be critical for the exceptional (...) ability of capture silk to stretch and recoil. Each ensemble of motifs was found to correspond to a different exon within the flagelliform gene. The pattern of sequence similarity among exons indicates intragenic concerted evolution. Surprisingly, the introns between the iterated exons are also homogenized with each other. This unusual molecular architecture in the flagelliform silk gene has implications for the evolution and maintenance of spider silk proteins. BioEssays 23:750–756, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

Are acids natural kinds? Or are they merely relevant kinds? Although acidity has been one of the oldest and most important concepts in chemistry, surprisingly little ink has been spilled on the natural kind question. I approach the question from the perspective of microstructural essentialism. After explaining why both Brønsted acids and Lewis acids are considered functional kinds, I address the challenges of multiple realization and multiple determination. Contra Manafu and Hendry, I argue that the stereotypical (...) properties of acids are not multiply realized. Instead, given the equivalence between the proton-donating and electron-accepting mechanisms of Brønsted and Lewis, respectively, I show that acidity as a property type can be identified with a unique microstructural property, namely the presence of a LUMO or other low energy empty orbital. In doing so, I defend the view that the Lewis theory encompasses Brønsted–Lowry, and that all Brønsted acids are also Lewis acids. Contra Hacking and Chang, I thus maintain that the different concepts of acidity do not crosscut, and that the hierarchy requirement is met. Finally, by characterizing natural kinds as powerful objects and by adopting a dispositional view of functions, I illustrate how the microessentialist can make sense of the latent and relational character of most acids. In sum, I contend that acids are genuine natural kinds, even for the microstructural essentialist. (shrink)

For a period of several years the philosopher of science Hasok Chang has promoted various inter-related views including pluralism, pragmatism, and an associated view of natural kinds. He has also argued for what he calls the persistence of everyday terms in the scientific view. Chang claims that terms like phlogiston were never truly abandoned but became transformed into different concepts that remain useful. On the other hand, Chang argues that some scientific terms such as acidity have suffered a form of (...) “rupture”, especially in the case of the modern Lewis definition of acids. Chang also complains that the degree of acidity of a Lewis acid cannot be measured using a pH meter and seems to regard this as a serious problem. The present paper examines some of these views, especially what Chang claims to be a rupture in the definition of acidity. It is suggested that there has been no such rupture but a genuine generalization, on moving from the Brønsted-Lowry theory to the Lewis theory of acidity. It will be shown how the quantification and measurement of Lewis acidity can easily be realized through the use of equilibrium theory and the use of stability constants. (shrink)

Among the many acid-base concepts, the theory of Usanovich is one of the least known despite the most general scope including almost all chemical reaction types and even redox chemistry. Published 1939 in a Soviet journal in Russian language, it gained little immediate attention, and was later criticized mainly as being too broad in scope. Although several articles recently remembered Usanovich and his acid–base theory, one major inconsistency again was overseen: the electron is put in a row along with anions. (...) Chemical history probably correctly puts this concept aside, also because it added little explanation capabilities beyond the elaborated considerations of the simultaneously published acid–base theory of Gilbert N. Lewis which was later refined by Pearson (hard and soft acids and bases, “HSAB”). A modified version of the core of Usanovich' concept is finally discussed. It combines the classic protic and aprotic acid–base concepts on the foundations of Lewis’ and Pearsons ideas. (shrink)

An Example of Teaching of Chemistry Before and After Mendeleev’s 1869 Periodic Table of Elements is presented. Prior to Mendeleev’s publication in 1869, only 63 elements were known. The ensuing discovery of the electron and the correspondence of the number of electrons to equivalent weight and atomic number is of singular importance to the impact of the Periodic Table of Elements and the way modern chemistry is taught. Without the identity of the electron and its alliance to atomic number, modern (...) teaching of chemistry would be very different. Without it concepts of electronic configuration, oxidation and reduction, polarization, intermolecular interactions, types of bonding, Lewis acid/base definition, etc. would disappear in our vernacular. Thus, we trace the origin of the electron. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:The Three Pillars of Catholic EducationArchbishop Salvatore CordileoneIntroductionOn February 13, 1999, then-Cardinal Joseph Ratzinger visited St. Patrick's Seminary and University in Menlo Park, California. He gave a lecture entitled, "Faith and Culture." Pope St. John Paul II had only back in September of the previous year published his momentous encyclical Fides et Ratio. Purposely placing his own remarks under the umbrella of that encyclical, Cardinal Ratzinger used the opportunity (...) at St. Patrick's Seminary to discuss the growing relativism which was even at that time eroding our culture.He began his lecture by using an example from C. S. Lewis's great work The Screwtape Letters. The future Pope remarked:This book consists of fictional letters from a senior devil who is giving advice on how best to proceed to one beginning in the work of leading men astray. The younger devil has expressed concern to his superior that especially intelligent people, in particular, might read the books of wisdom of the ancients and might thus come upon the track of the truth. Screwtape calms him by pointing out that the "Historical point of View," with which the intellectuals of the Western world have fortunately been inculcated by the devils, means in fact that "when a learned man is presented with any statement in an ancient author, the one question he never asks is whether it [End Page 7] is true. He asks who influenced the ancient writer, and how far the statement is consistent with what he said in other books, and what phase in the writer's development, or in the general history of thought, it illustrates, and how it affected other writers," and so on.1The startling truth is that now, almost twenty-five years later, what Cardinal Ratzinger articulated back in 1999 has only crystallized. In almost every area of our culture, the notion of truth has receded due to the acidic encroachment of relativism. As a culture we have given up on any hope of finding truth and instead consigned reality to something that is determined by the individual. We see the extent to which this relativism has taken hold of our culture in the now-famous words of Supreme Court Justice Anthony Kennedy: "At the heart of liberty is the right to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life."2 In this breathtaking statement, Justice Kennedy seemingly makes irrelevant the entire history of Western civilization. The irony, of course, is that it is precisely the course of Western philosophy and thought which has steered the culture in such a direction that it could produce a Supreme Court justice who would articulate such a bewildering statement. For we do not, nor can we, exist in a philosophical vacuum. And such is the great irony of this moment that we occupy—it is on the ash heap of Western civilization that relativists stand attacking the very history which brought them to be there in the first place.Given this sad reality, we can see Cardinal Ratzinger's criticism from 1999 as a clarion call, and as prophetic in describing what has transpired in the decades since. The complete dominance of relativism in all its forms demands that we return to the primacy of truth. But it is not only unfettered relativism that necessitates this return to truth. The return to the splendor of truth becomes all the more important for us as Christians. As the First Letter of St. Peter makes clear, the Christian is to purify his soul by obedience to the truth (1 Pet1:22). And in the Gospel of St. John, we are told that Christ is the true Light who enlightens all, and who gives the power to become children of God to those who receive him (John 1:9–11).In this vein, I would like to present what I believe is the strength of Catholic education and the need to restore a truly Catholic vision. To this end, I believe Cardinal Ratzinger was correct in his forecast of the repercussions of bracketing out truth from our culture. While the broader repercussions of... (shrink)

SummaryKekulé first suggested a hexagonal structure for benzene in 1865. For over a half-century after, chemists struggled to reconcile proposed structures for benzene and other aromatic compounds with their resistance to chemical transformation and tendency to maintain the type during reaction. The combined structural and reactivity features of these compounds were eventually covered by the term ‘aromaticity’. Kekulé, Bamberger and Thiele had each proposed a criterion for aromaticity; all were either empirically contradicted or incapable of evaluation. In the 1930s, two (...) rival quantum mechanical methods succeeded in establishing a physical basis for aromaticity. Using valence bond theory, Pauling attributed benzene's stability to its being a resonance hybrid of several Lewis structures. Calculating resonance energies was challenging but manipulating Lewis structures was not; that procedure provided qualitative insights into aromatic structure and reactivity. Resonance theory appealed especially to organic chemists and eclipsed Hückel's contemporaneous molecular orbital approach, which remained relatively inaccessible. In the 1950s, however, simple rules derived from Hückel's mathematics, combined with proton NMR data, provided seemingly universal criteria for aromaticity. In the event, post-1950 discoveries of non-organic, three-dimensional compounds such as ferrocene and the fullerenes that exhibit aromatic properties led chemists to doubt the utility and universality of ‘aromaticity’ as a concept. A recent consensus maintains that aromaticity is a multi-variable phenomenon that cannot be reduced to a strict definition, a property it shares with other core chemical concepts such as ‘acidity’ and ‘reactivity’. (shrink)

It is a platitude that when we reason, we often take things for granted, sometimes even justifiably so. The chemist might reason from the fact that a substance turns litmus paper red to that substance being an acid. In so doing, they take for granted, reasonably enough, that this test for acidity is valid. We ordinarily reason from things looking a certain way to their being that way. We take for granted, reasonably enough, that things are as they look Although (...) it is a platitude that we often take things for granted when we reason—whether justifiably or not—one might think that we do not have to. In fact, it is a natural expectation that were we not pressed by time, lack of energy or focus, we could always in principle make explicit in the form of premises every single presupposition we make in the course of our reasoning. In other words, it is natural to expect it to be true that presuppositionless reasoning is possible. In this essay, I argue that it is false: presuppositionless reasoning is impossible. Indeed, I think this is one of the lessons of a long-standing paradox about inference and reasoning known as Lewis Carroll’s (1985) regress of the premises. Many philosophers agree that Carroll’s regress teaches us something foundational about reasoning. I part ways about what it is that it teaches us. What it teaches us is that the structure of reasoning is constitutively presuppositional. (shrink)

In quantum mechanics it is usually assumed that mutually exclusives states of affairs must be represented by orthogonal vectors. Recent attempts to solve the measurement problem, most notably the GRW theory, require the relaxation of this assumption. It is shown that a consequence of relaxing this assumption is that arithmatic does not apply to ordinary macroscopic objects. It is argued that such a radical move is unwarranted given the current state of understanding of the foundations of quantum mechanics.

Biological modalities (e.g., biological possibility, necessity and counterfactuality) play an important explanatory role in biological practice. However, biological modalities lack truth conditions and the inferential relationship between biological and other modalities is unclear. This thesis addresses these problems, first, by improving upon Daniel Dennett's Library of Mendel. Second, a family of modal logics is introduced. In the simplest model, states are interpreted as codons, the binary relation is interpreted as single substitution mutation and the valuation induces a partition of blocks (...) of codons that code for some amino acid. In addition, the proposed framework allows for a grading of biological possibility and captures various competing notions of biological possibility. Applications include a model checker and a lawless Lewis-style semantics for biological counterfactuals. In short, this thesis lays the groundwork for a theory of biological modalities. (shrink)

Learn to think critically with the leading introduction to reasoning and argumentation. Highlights In clear, reader-friendly language, The Power of Critical Thinking provides an engaging introduction to argumentation, deductive and inductive reasoning, inferencing, and evaluating scientific theories New Critical Thinking and the Media boxes in each chapter apply the principles of critical thinking to the realms of media, advertising, and news New content on "fake news," the COVID-19 pandemic, and other important contemporary topics reflects the changing world in which today's (...) students must apply their critical thinking abilities New and updated exercises offer extensive opportunities for students to practise the skills through which they will become active, engaged critical thinkers Additional online resources-including a study guide and practice quizzes for students as well as an instructor's manual, a test bank, and PowerPoint slides for instructors-offer stimulating materials to enhance the learning and teaching experiences. About the Authors Chris MacDonald is an associate professor and chair of the Law and Business Department at the Ted Rogers School of Management, Toronto Metropolitan University. Lewis Vaughn is an independent scholar and author of several textbooks on philosophy, ethics, and critical thinking. (shrink)

CHAPTER The Excommunication of Baruch Spinoza The Decree of Anathema A man excommunicate is a man alone. He is severed from his past, his parents, teachers , ...

In this short essay I address the central topic of the Centenary Workshop on Acidity, that is the relations of the classical protonist acid–base theory by Brønsted and the electronist approach by Lewis. Emphasis is laid on the empirical background of both approaches and the over-theoretization of chemical phenomena (essentialism) is criticized.

The fact that especially few women survive in a subject that attracts roughly equal numbers of male and female undergraduates suggests that, while bothsexes are equally drawn to philosophy, there is something about the discipline that is discouraging to women.

Human genetics has blossomed from an obscure biological science and explanation for rare disorders to a field that is profoundly altering health care for everyone. This thoroughly updated new edition of _Human Genetics: The Basics_ provides a concise background of gene structure and function through the lens of real examples, from families living with inherited diseases to population-wide efforts in which millions of average people are learning about their genetic selves. The book raises compelling issues concerning: • The role of (...) genes in maintaining health and explaining sickness • Genetic testing, gene therapy, and genome editing • The common ancestry of all humanity and how we are affecting our future. Written in an engaging, narrative manner, this concise introduction is an ideal starting point for anyone who wants to know more about genes, DNA, genomes, and the genetic ties that bind us all. (shrink)

The topic of homonymy, especially the variety of homonymy that has gone under the title, “focal meaning,” is of fundamental importance to large portions of Aristotle’s work-not to mention its central place in the ongoing controversies between Aristotle and Plato. It is quite astonishing, therefore, that the topic should have gone so long without a book-length treatment. And it is all the more gratifying that the new book on homonymy by Christopher Shields should be so comprehensive, and of such uniformly (...) high quality.’ Everyone who cares about Aristotle will be in his debt. Shields’s book falls into two parts. In the first, he is concerned to lay out the basic structure of Aristotle’s views about homonymy; in the second part, we are led through the various applications of the idea, to the analysis of friendship, for example, the homonymy of the body, the account of goodness and, not least, the homonymy of being. Shields’s book brings out well how the topic of homonymy weaves in and out of the fabric of Aristotle’s thinking in a variety of areas. I will resist the temptation to follow Shields through these various subject-matters, and instead take up essentially two topics. First, (I), the basic outline of Aristotle’s notion of homonymy, more or less independently of its different applications (here, I follow Shields’s example in the first half of his book). Thereafter, I discuss a single application: the homonymy of being (this is the subject of Shields’s last and longest chapter). Here, I will be interested (II) in how homonymy relates to the theory of the categories; and (III) in the application of homonymy to the analysis of substance in the Metaphysics. (shrink)

Created as a poetic and visual journey, Touchless Automatic Wonder spans twenty-five years and four continents. These striking photographs capture “found text”: the sometimes mysterious, occasionally humorous, often cryptic presence of words in the everyday landscape. In Koch’s lyrical sequencing, the images reveal obscure and eccentric voices in their various and distinctive roles on the daily stage of the world around us. This intriguing approach at the intersection of language, image, and the social landscape will appeal to readers interested in (...) contemporary art and photography, popular culture, and conceptual concerns both literary and visual. (shrink)