In this paper we suggest adding to predicate modal and temporal logic a locality predicate W which gives names to worlds (or time points). We also study an equal time predicate D(x, y)which states that two time points are at the same distance from the root. We provide the systems studied with complete axiomatizations and illustrate the expressive power gained for modal logic by simulating other logics. The completeness proofs rely on the fairly intuitive notion of a configuration in order (...) to use a proof technique similar to a Henkin completion mixed with a tableau construction. The main elements of the completeness proofs are given for each case, while purely technical results are grouped in the appendix. (shrink)

What place has poetry in the teaching or reflection of ethicists? Even poetry that has no obvious political edge can play an important role in refining a poetics of the will, where will is understood at once as the motive power of action and as the seat of both our freedom and our bondage. Poems by W. H. Auden, Anthony Hecht, Galway Kinnell, William Carols Williams, and others are examined against a background provided by the work of Erazim Kohák, H. (...) Richard Niebuhr, and Paul Ricoeur. A poetics of the will requires attention to affirmation, beauty, and wonder, but also to concrete embodiment, full recognition of the complex reality of persons and situations, and mature resistance to the temptation to righteousness and the seduction of despair. (shrink)

As the third volume of a trilogy which also comprises The Insect Societies and Sociobiology, On Human Nature sets out to identify and to solve certain contemporary spiritual "dilemmas." According to Wilson, we have now clearly recognized that the intersection of the causality of natural selection with that of environmental necessity explains human nature. This awareness, he suggests, has brought us today to experience these three dilemmas: first, that the human species "lacks any goal external to its own biological nature"; (...) second, that "morality evolved as instinct"; and finally, that we will soon be able to control our own evolution through molecular engineering and cloning. For Wilson, human life has no transcendent source of meaning, of moral values, or of guidance for its own future evolution. Having offered this diagnosis of the human condition, Wilson prescribes replacing the old humanistic, religious, and Marxist mythologies with wholehearted assent to "the mythology of scientific materialism." Wilson's sociobiological version of scientific materialism has, he claims, the added power of being able to explain the old mythologies themselves as products of natural selection and cultural determinism. The minimum claims of the "evolutionary epic" are these. (shrink)

Although Michael Polanyi's model of science and his construal of the nature of the real are usually thought to be congenial to religion and although Polanyi himself says that “the stage on which we thus resume our full intellectual powers is borrowed from the Christian scheme of Fall and Redemption” (Polanyi 1958, 324), theologians have given little attention to the model of God he presents. The metaphysical and theological vision unfolded in part 4 of Personal Knowledge is a thoughtful (...) alternative to materialist versions of neo‐Darwinism and provides a platform for revisiting four long‐standing controversies at the interface of science and religion: whether life and mind can be completely specified in terms of physical analysis, whether nature can be adequately understood without appeal to final causes, whether natural selection adequately explains life's diverse forms, and whether knowledge can be fully objectified. Through an exploration of Polanyi's contribution to these discussions, we undertake to show not only that his treatment of God as a cosmic field is strikingly original but also that in reinstating activity as a metaphysical category, he reconstructs our understanding of our creaturely hope and calling. (shrink)

We consider the potential impact of Computer Supported Cooperative Work, with special reference to large technically advanced projects involving several organizations. It is vital that such projects are managed efficiently, without delays, since a product that reaches the market a few months earlier than its competitors enjoys a great advantage. Traditional methods of coordinating large projects, based on hierarchical communication, tend to produce delays, since technicians at remote sites are obliged to solve coordination problems by passing them up the hierachy. (...) It would be better if such problems were solved by improvising conferences among the technicians; Computer Supported Cooperative Work will provide the technical means of implementing this heterarchical style of management without losing control of the project. The use of computers as a social medium raises methodological and ethical issues which are discussed in the final section. (shrink)

Drawing from a four-year study of US science institutions that support biological control of arthropods, this article examines the decline in biological control institutional capacity in California within the context of both declining public interest science and declining agricultural research activism. After explaining how debates over the public interest character of biological control science have shaped institutions in California, we use scientometric methods to assess the present status and trends in biological control programs within both the University of California Land (...) Grant System and the California Department of Food and Agriculture. We present available data on the number of scientific positions and the types of positions to discuss the impact on the amount of public interest research on biological control in California. We use sociograms to depict how biological control science networks have been reconfigured over time. Our quantitative and qualitative analyses indicate that the following factors contributed to the decline of biological control science in California over the 45-year period analyzed: (1) the institutional reconfiguration of university research priorities; (2) the fraying networks within and increasing specialization of biological control science; (3) the transformation of the social organization of the life science work, including privatization; and (4) the abandonment of this thematic area by civil society activist groups. This broad array of forces suggests that biological control, as a public interest science, will require a deliberate intervention, based on advocacy of clear public interest criteria. (shrink)

How ought the historian to reconcile themselves philosophically with the fact of evental contingency and of its relationship to structural determination? Does the existence of contingent causation undermine the very concept of historical necessity, or do the two instead in dialectical entanglement? In this essay, I engage with the problem of historical contingency from a transcendental-materialist perspective informed by the work of Slavoj Žižek, tendering a philosophically serious response to the famous Pascalian conundrum of Cleopatra’s nose and its challenge to (...) structuralist accounts of historical causation. The position associated with Laplace – that is to say, that the course of history would be entirely predictable were one provided with a complete account of initial conditions – is firmly rejected. Instead, I revive Althusser’s attempt to craft a theory of ‘aleatory materialism’, in which the determinative power of structural forces nevertheless leave space for the radical and unpredictable transformation of a situation by the chance crystallisation of events and encounters. In this effort, I recruit conceptual architecture not only from the fields of historiography and philosophy, but also quantum physics, psychoanalysis, and mathematics. (shrink)

Primordial emotions are the subjective element of the instincts which are the genetically programmed behaviour patterns which contrive homeostasis. They include thirst, hunger for air, hunger for food, pain and hunger for specific minerals etc.There are two constituents of a primordial emotion—the specific sensation which when severe may be imperious, and the compelling intention for gratification by a consummatory act. They may dominate the stream of consciousness, and can have plenipotentiary power over behaviour.It is hypothesized that early in animal evolution (...) complex reflex mechanisms in the basal brain subserving homeostatic responses, in concert with elements of the reticular activating system subserving arousal, melded functionally with regions embodied in the progressive rostral development of the telencephalon. This included the emergent limbic and paralimbic areas, and the insula. This phylogenetically ancient organization subserved the origin of consciousness as the primordial emotion, which signalled that the organisms existence was immediately threatened. Neuroimaging confirms major activations in regions of the basal brain during primordial emotions in humans. The behaviour of decorticate humans and animals is discussed in relation to the possible existence of primitive awareness.Neuroimaging of the primordial emotions reveals that rapid gratification of intention by a consummatory act such as ingestion causes precipitate decline of both the initiating sensation and the intention. There is contemporaneous rapid disappearance of particular regions of brain activation which suggests they may be part of the jointly sufficient and severally necessary activations and deactivations which correlate with consciousness [Crick, F. & Koch, C. . A framework for consciousness. NatureNeuroscience,6, 119–126]. (shrink)

Lucas plays off his understandings of the problem of freedom and Gödel's Theorem, concluding that, "... a human being cannot be represented by a logistic calculus and therefore cannot be described completely in terms of physical variables, all of whose values are completely determined by the conjunction of their values at some earlier time". Lucas approaches the problem of freedom from the perspective of a computer programmer. His argument is as follows. Men can construct a logistic calculus, L, of which (...) Gödel's theorem is a theorem. Gödel's theorem is known-by-men-to-be-true, which is a fact. Facts have ontological status. Any attempt to represent this fact by a definite description must result in an infinite regress of meta-L's, for a Gödel theorem can be constructed in any meta-L powerful enough to show that Gödel's theorem is a theorem of L. Accordingly, men can do something which cannot be represented within L; men are therefore undeterminable. Lucas's position amounts to a rethinking of Fichte's position, set in the metaphor of meta-mathematical logic. However, whereas Fichte concluded that a man can choose to posit that he is free, and thereby make himself free, Lucas concludes that all men are free since some men know that Gödel's theorem is true. One question suggested by Lucas's argument is ontological, and another is epistemological. First, what is the ontological status of facts? Secondly, what is the distinction between knowing-that-p and showing-that-p? Ultimately, Lucas's demonstration pivots on equating the-completeness-of-L with knowing-the-completeness-of-L. It remains to be shown that that which is capable of knowing-that-p is governed in the act of knowing-that-p by the conditions which determine p.--M. D. P. [[sic]]. (shrink)

Successful interactions between people are dependent on rapid recognition of social cues. We investigated whether head direction – a powerful social signal – is processed in the absence of conscious awareness. We used continuous flash interocular suppression to render stimuli invisible and compared the reaction time for face detection when faces were turned towards the viewer and turned slightly away. We found that faces turned towards the viewer break through suppression faster than faces that are turned away, regardless of eye (...) direction. Our results suggest that detection of a face with attention directed at the viewer occurs even in the absence of awareness of that face. While previous work has demonstrated that stimuli that signal threat are processed without awareness, our data suggest that the social relevance of a face, defined more broadly, is evaluated in the absence of awareness. (shrink)

In this article, the authors introduce the POWER perspective of police wellness and ethics. POWER stands for Police Officer Wellness, Ethics, and Resilience. The perspective represents the view that wellness and ethics cannot be discussed separately; they are inextricably connected to each other. Initiatives to address one should always, simultaneously, include the other. Although there is a need for wellness and ethics to be addressed on an organizational level, the present article emphasizes the importance of POWER for individual police officers. (...) The authors make the argument that officers need to expand the way in which they conceptualize their own wellness to include efforts to maintain ethical decision-making. Specifically, officers will remain psychologically healthier when they take active steps to stay steadfastly committed to their ethical principles. Likewise, officers who utilize a comprehensive wellness program, including strategies to boost resilience, will be far less likely to experience lapses in ethical decision-making. Further recommendations for action and implication of this matter in law enforcement are presented and discussed. (shrink)

We analyse the projected future evolution of the distribution of voting power and related quantities under the qualified majority decision rule for the Council of Ministers of the EU, prescribed by the forthcoming EU Reform Treaty. Our projections are based on the demographic changes forecast by eurostat [4] for the period stretching from the present to the middle of the 21st Century. We use a method similar to the one we used in [6], [7], [8] and [9].

COVID-19 exposed flaws in the law regulating the sharing of data and human biological material. This poses obstacles to the epidemic response, which needs accelerated public health research and, in turn, efficient and legitimate HBM and data sharing. Legal reform and development are needed to ensure that HBM and data are shared efficiently and lawfully. Academics have suggested important legal reforms. The first is the clarification of the susceptibility of HBM and HBM derivatives to ownership, including, inter alia, the promulgation (...) of a revised version of the South African Material Transfer Agreement by the Minister of Health. This would remove uncertainty regarding the current SA MTA’s perpetual donor ownership clause. The second is the development of data trusts, the adoption of open access to research data, and the creation of an African ‘data corridor’. This would ensure that data are protected while allowing for the efficient transfer of data between researchers for the collective good and in the interest of the public. The third is the amendment of the Space Affairs Act to extend the powers of the Council of Space Affairs to include the management of data collected through the utilisation of Earth observation and geographical information systems. This would ensure the protection of outer space data, legislating its use and sharing once it lands on Earth. The implementation of these legal reforms and developments will better prepare SA to face future epidemics from a health research perspective. (shrink)

In this paper, we examine how organizations’ impression management evolves in response to rising stakeholder pressures regarding organizations’ corporate responsibility initiatives. We conducted a comparative case study analysis over a period of 13 years for two organizations—Exxon and BP—that took extreme initial stances on climate change. We found that as stakeholder pressures rose, their IM tactics unfolded in four phases: advocating the initial stance, sensegiving to clarify the initial stance, image repairing, and adjusting the stance. Taken together, our analysis of (...) IM over these four phases provides three key insights about the evolution of IM in the face of rising pressures. First, when faced with stakeholder pressures, it seems that organizations do not immediately resort to conforming but tend to give in gradually when pressures increase and start to come from relatively powerful stakeholders. Second, evolution of IM seems to be characterized by path dependence, i.e., even as organizations’ positions evolve, they continue to show their conviction in their initial positions and try to convey that their subsequent positions flow logically from the previous ones. Finally, IM involves navigation between symbolism and substance, and companies tend to strive toward harmonizing their symbolic and substantive actions as stakeholder pressure increases. (shrink)

This essay addresses mineral water as a medical, experimental and economic material. It focuses on the career of the Reverend Dr William Laing , a physician and cleric who wrote two pamphlets about the water of provincial spa located in Peterhead, a town on the north-east coast of Scotland. I begin by outlining his education and I then reconstruct the medical theory that guided his efforts to identify tonics in the well’s water. Next, I explain why Laing and several other (...) local inhabitants thought themselves to be authorities on the palliative power of the water and I close by showing how such effects were commodified by local entrepreneurs. Although I concentrate primarily upon Peterhead Spa, this study touches upon several issues relevant to the types of medical theory and chemical experimentation that were being used in provincial Scotland during the late eighteenth and early nineteenth centuries. (shrink)

How do people come to opposite causal judgments about societal problems, such as whether a public health policy reduced COVID‐19 cases? The current research tests an understudied cognitive mechanism in which people may agree about what actually happened (e.g., that a public health policy was implemented and COVID‐19 cases declined), but can be made to disagree about the counterfactual, or what would have happened otherwise (e.g., whether COVID‐19 cases would have declined naturally without intervention) via comparison cases. Across two preregistered (...) studies (total N = 480), participants reasoned about the implementation of a public policy that was followed by an immediate decline in novel virus cases. Study 1 shows that people's judgments about the causal impact of the policy could be pushed in opposite directions by emphasizing comparison cases that imply different counterfactual outcomes. Study 2 finds that people recognize they can use such information to influence others. Specifically, in service of persuading others to support or reject a public health policy, people systematically showed comparison cases implying the counterfactual outcome that aligned with their position. These findings were robust across samples of U.S. college students and politically and socioeconomically diverse U.S. adults. Together, these studies suggest that implied counterfactuals are a powerful tool that individuals can use to manufacture others’ causal judgments and warrant further investigation as a mechanism contributing to belief polarization. (shrink)

Current debates about “Darwinizing culture” have typically focused on the validity of memetics. In this article we argue that meme-like inheritance is not a necessary requirement for descent with modification. We suggest that an alternative and more productive way of Darwinizing culture can be found in the application of phylogenetic methods. We review recent work on cultural phylogenetics and outline six fundamental questions that can be answered using the power and precision of quantitative phylogenetic methods. However, cultural evolution, like biological (...) evolution, is often far from treelike. We discuss the problems reticulate evolution can cause for phylogenetic analyses and suggest ways in which these problems can be overcome. Our solutions involve a combination of new methods for the study of cultural evolution , and the triangulation of different lines of historical evidence. Throughout we emphasize that most debates about cultural phylogenies can only be settled by empirical research rather than armchair speculation. (shrink)

The problem of unhappiness is deceptively simple. It is all pervasive, and susceptible to highly theoretical formulations and explanations. In this work, Martin Kalin explores and evaluates two theories which compete as explanations of human unhappiness. Marxism is a utopian theory, in that Marx’s identification of the sources of unhappiness predicts their removal, or at least their radical diminution. Man’s alienation from his work and from his own species is necessary for pre-capitalist and capitalist historical developments. But communist society arises (...) out of that revolution which overcomes precisely those historical conditions which cause alienation. Thus Marx holds that human unhappiness can be and will be overcome in human history. But Marx’s theory has difficulty accounting for the revolutionary forces which will bring this about. And more, Marx’s concept of man includes the notion that human powers are always adequate to human needs. Freudian psychoanalysis especially questions this last point. (shrink)

The construct of the self is important in the domain of memory research. Recent work has shown that person memory is influenced by similarity of social targets to the self. The current experiments investigate self-similarity as defined by traits and political ideology to better understand how memory for social targets is organised. Across three experiments, participants formed positive or negative impressions based on each target’s picture, a trait-implying behavior (Experiments 1 & 2), and/or political ideology (conservative/liberal label in Experiment 2; (...) political-ideological belief statements in Experiment 3) followed by a memory test. Results showed a self-similarity effect dependent on valence in Experiment 1, but not in Experiments 2 or 3 when participants processed ideological information associated with targets. These results suggest that self-similarity has an effect on memory for social targets, but that ideological information disrupts self-focused processing of others, suggesting that ideological information also has a powerful influence on what people remember about others (i.e. social targets). (shrink)

The history of the dyestuffs industry during the period 1775–1860 is interesting for three reasons. In the first place it was in connection with the manufacture of synthetic dyestuffs, begun in 1856, that the industrial research laboratory and the organization scientist first unmistakably appeared in the last decades of the nineteenth century. Secondly, there are the enigmas of W. H. Perkin, the man who discovered and manufactured the first coal-tar colours, but who retired somewhat abruptly from the industry in 1874: (...) just after the synthesis of alizarine. Thirdly, the dyestuffs industry was in intimate association with the textile industries which had for a long time been subject to frequent radical scientific and technological innovation. Among the most important of these we may mention John Smeaton's classic paper of 1759 on the maximum work obtainable from a given fall of water: a problem important not only for the abstract science of mechanics, but also for the design of waterwheels—the main source of power for the early textile mills. (The waterwheel was not, during the eighteenth century, the epitome of the quaint and picturesque: it was in the van of scientific and technical progress.) Again, the textile industries were quick to employ the Watt rotative engine; previously a two cylinder Newcomen engine had been tried out. Bleaching powders, based on Scheele's discovery of chlorine and its properties, were rapidly adopted: in this context one cannot help contrasting the indifference of medical science to Davy's early suggestion of using nitrous oxide as an anaesthetic; or Faraday's comment in 1818 on the anaesthetic power of sulphuric ether. The textile industries saw, over this period, a rapid succession of new machines, the pace of invention being so hot that in 1832 Charles Babbage reported that machines became obsolete long before they wore out. A Salford cotton mill was the first industrial establishment to use gas lighting: James Thomson, calico printer, introduced gas lighting to the town of Clitheroe when he installed it in his works. And there were many other important technical and scientific innovations. It was to supply these industries, so well accustomed to change, that the synthetic coal-tar dyestuffs were introduced from 1856 onwards. It is interesting that, so far as we can see, the appearance of these synthetic dyestuffs was the last in the series of major innovations in the textiles and related industries: at least until recent times. (shrink)

Clinical responses to dopamine replacement therapy for individuals with Parkinson’s disease are often difficult to predict. We characterized changes in MDS-UPDRS motor factor scores resulting from a short-duration L-Dopa response, and investigated how the inter-subject clinical differences could be predicted from motor cortical magnetoencephalography. MDS-UPDRS motor factor scores and resting-state MEG recordings were collected during SDR from twenty individuals with a PD diagnosis. We used a novel subject-specific strategy based on linear support vector machines to quantify motor cortical oscillatory frequency (...) profiles that best predicted medication state. Motor cortical profiles differed substantially across individuals and showed consistency across multiple data folds. There was a linear relationship between classification accuracy and SDR of lower limb bradykinesia, although this relationship did not persist after multiple comparison correction, suggesting that combinations of spectral power features alone are insufficient to predict clinical state. Factor score analysis of therapeutic response and novel subject-specific machine learning approaches based on subject-specific neuroimaging provide tools to predict outcomes of therapies for PD. (shrink)

Algorithmic biases, or algorithmic unfairness, have been a topic of public and scientific scrutiny for the past years, as increasing evidence suggests the pervasive assimilation of human cognitive biases and stereotypes in such systems. This research is specifically concerned with analyzing the presence of discursive biases in the text generated by GPT-3, an NLPM which has been praised in recent years for resembling human language so closely that it is becoming difficult to differentiate between the human and the algorithm. The (...) pertinence of this research object is substantiated by the identification of race, gender and religious biases in the model’s completions in recent research, suggesting that the model is indeed heavily influenced by human cognitive biases. To this end, this research inquires: How does the Natural Language Processing Model GPT-3 replicate existing social biases?. This question is addressed through the scrutiny of GPT-3’s completions using Critical Discourse Analysis (CDA), a method which has been deemed as amply valuable for this research as it is aimed at uncovering power asymmetries in language. As such, the analysis is specifically centered around the analysis of gender and race biases in the model’s generated text. Research findings suggest that GPT-3’s language generation model significantly exacerbates existing social biases while replicating dangerous ideologies akin to white supremacy and hegemonic masculinity as factual knowledge. (shrink)

This paper concludes a special feature of Sustainability Science that explores a broad range of social value theoretical traditions, such as religious studies, social psychology, indigenous knowledge, economics, sociology, and philosophy. We introduce a novel transdisciplinary conceptual framework that revolves around concepts of 'lenses' and 'tensions' to help navigate value diversity. First, we consider the notion of lenses: perspectives on value and valuation along diverse dimensions that describe what values focus on, how their sociality is envisioned, and what epistemic and (...) procedural assumptions are made. We characterise fourteen of such dimensions. This provides a foundation for exploration of seven areas of tension, between: (1) the values of individuals vs collectives; (2) values as discrete and held vs embedded and constructed; (3) value as static or changeable; (4) valuation as descriptive vs normative and transformative; (5) social vs relational values; (6) different rationalities and their relation to value integration; (7) degrees of acknowledgment of the role of power in navigating value conflicts. In doing so, we embrace the 'mess' of diversity, yet also provide a framework to organise this mess and support and encourage active transdisciplinary collaboration. We identify key research areas where such collaborations can be harnessed for sustainability transformation. Here it is crucial to understand how certain social value lenses are privileged over others and build capacity in decision-making for understanding and drawing on multiple value, epistemic and procedural lenses. (shrink)

Scholars have long pointed to the power of music as a primary source in instruction for bringing past actors into sharper view and engender deeper connections with the past. By employing Dimitri Shostakovich's 7th Symphony, composed amidst the Nazi siege of Leningrad during the Second World War, we sought to explore, more precisely, the nature of how music, as a primary source, enhances the study of history among students. Through the formulation, execution, and assessment of a two-day lesson with students (...) in five secondary history classes, three of which listened to the symphony and two of which did not, we found that the incorporation of the symphony resulted in students’ enhanced empathetic understanding of the past. Implications include details regarding profound opportunities for, as well as challenges to, cultivating historical empathy through the use of music as a primary source. (shrink)

This paper explores gender barriers to the formation of the female mentor – male protégé relationship. The authors consider both physiological as well as social gender as a way to help understand the scarcity of these relationships. A number of gender-related factors are considered, including organizational demographics, relational demography, sexual liaisons, gender stereotypes, gender behaviors, and power dynamics. The paper concludes with directions for future research that will help provide further insights into the development and success of the female mentor (...) – male protégé relationship. (shrink)

Comparing the degree of openness of the economy of Poland and the Netherlands, we can say the following. The Netherlands is more dependent on foreign trade than Poland. The Netherlands export quota reaches almost 50%, unlike 41,37% in Poland in 2016. However, Poland has become more import-dependent. Poland, in contrast to the Netherlands, is continuing to increase the indicators of "economic globalization". To date, the Netherlands has been pursuing more moderate foreign trade policy and trying to protect itself from external (...) risks by focusing on an internal market with high purchasing power. On the contrary, Polish politics tries to focus on the new markets for its products in order to increase the prosperity and well-being of its citizens. Poland as a country and an economic entity has made a qualitative leap in its development. The economy of this country has become more open and integrated into the world economy. (shrink)

This paper offers a two dimensional variation of Standard Deontic Logic SDL, which we call 2SDL. Using 2SDL we can show that we can overcome many of the difficulties that SDL has in representing linguistic sets of Contrary-to-Duties (known as paradoxes) including the Chisholm, Ross, Good Samaritan and Forrester paradoxes. We note that many dimensional logics have been around since 1947, and so 2SDL could have been presented already in the 1970s. Better late than never! As a detailed case study (...) illustrating the power of 2SDL, we examine the system DL of Deontic Logic of Andrew Jones and Ingmar Pörn offered in 1985 to solve the Chisholm paradox of Contrary to Duties. The critical examination is done using logics and methods available in 1985 and solutions are proposed using what was available in 1985. (shrink)

There’s a possibly more interesting general question: does technology transform and extend the mind and our mental powers? In a widely discussed 1998 paper titled “The Extended Mind”, Andy Clark and David Chalmers argue that mind and cognition can extend outside the head and can include items and processes in the world. In their thought experiment, Otto has alzheimer’s syndrome but does not lose his ability to function because he records information he learns in a notebook that he always (...) carries. Thus, C&C claim, Otto continues to have beliefs. The notebooks function as his memory. C&C propose a "parity principle": a part of the world is part of a cognitive process if it "functions as a process which, were it done in the head, we would have no hesitation in recognizing [it] as part of the cognitive process .... Cognitive processes ain't (all) in the head!" (in Menary p. 29, original emphasis). (shrink)

The first observations of dislocations by TEM were published in 1956. Since then the technique has been developed into an indispensable tool for the materials scientist, not only for the characterization of the extended defect structure of materials, but also for the elucidation of the mechanisms controlling their properties. To mark the 50th anniversary of the original work, this Special Issue consists of reprints of the three original papers and some 22 current state-of-the-art articles, which provide a snapshot of the (...) tremendous power and versatility of the technique at the present time. It is also hoped that this collection of papers from different areas of application and including different techniques might stimulate some cross-fertilization. In this introduction, we comment briefly on the context in which the original work was performed, trace some of the important developments that have taken place in the intervening period and identify some of the outstanding problems. (shrink)