Philosophical approach to understanding science
Critical realism is a philosophical approach to understanding science, and in particular social science, initially developed by Roy Bhaskar (1944–2014). It specifically opposes forms of empiricism and positivism by viewing science as concerned with identifying causal mechanisms. In the last decades of the twentieth century it also stood against various forms of postmodernism and poststructuralism by insisting on the reality of objective existence. In contrast to positivism's methodological foundation, and poststructuralism's epistemological foundation, critical realism insists that (social) science should be built from an explicit ontology. Critical realism is one of a range of types of philosophical realism, as well as forms of realism advocated within social science such as analytic realism and subtle realism.
A 2016 summary of what various accounts and versions of critical realism have in common, coauthored by nine scholars including Margaret Archer, Philip Gorski, Daniel Little, Christian Smith, and George Steinmetz, drew out four tenets:
Contemporary critical realism.
Overview.
Bhaskar developed a general philosophy of science that he described as transcendental realism and a special philosophy of the human sciences that he called critical naturalism. The two terms were combined by other authors to form the umbrella term critical realism.
Transcendental realism attempts to establish that in order for scientific investigation to take place, the object of that investigation must have real, manipulable, internal mechanisms that can be "actualized" to produce particular outcomes. This is what we do when we conduct experiments. This stands in contrast to empiricist scientists' claim that all scientists can do is observe the relationship between cause and effect and impose meaning. Whilst empiricism, and positivism more generally, locate causal relationships at the level of events, critical realism locates them at the level of the generative mechanism, arguing that causal relationships are irreducible to empirical constant conjunctions of David Hume's doctrine; in other words, a constant conjunctive relationship between events is neither sufficient nor even necessary to establish a causal relationship.
The implication of this is that science should be understood as an ongoing process in which scientists improve the concepts they use to understand the mechanisms that they study. It should not, in contrast to the claim of empiricists, be about the identification of a coincidence between a postulated independent variable and dependent variable. Positivism and naive falsificationism are also rejected on the grounds that a mechanism may exist but either a) go unactivated, b) be activated, but not perceived, or c) be activated, but counteracted by other mechanisms, which results in its having unpredictable effects. Thus, non-realisation of a posited mechanism cannot (in contrast to the claim of some positivists) be taken to signify its non-existence. Falsificationism can be viewed at the statement level (naive falsificationism) or at the theorem level (more common in practice). In this way, the two approaches can be reconciled to some extent.
Critical naturalism argues that the transcendental realist model of science is equally applicable to both the physical and the human worlds. However, it argues, when we study the human world we are studying something fundamentally different from the physical world and must, therefore, adapt our strategy to studying it. Critical naturalism, therefore, prescribes social scientific methods which seek to identify the mechanisms producing social events, but with a recognition that these are in a much greater state of flux than those of the physical world (as human structures change much more readily than those of, say, a leaf). In particular, we must understand that human agency is made possible by social structures that themselves require the reproduction of certain actions/pre-conditions. Further, the individuals that inhabit these social structures are capable of consciously reflecting upon, and changing, the actions that produce them—a practice that is in part facilitated by social scientific research.
Critical realism has become an influential movement in British sociology and social science in general as a reaction to, and reconciliation of postmodern critiques.
Developments.
Since Bhaskar made the first big steps in popularising the theory of critical realism in the 1970s, it has become one of the major strands of social scientific method, rivalling positivism/empiricism, and post-structuralism/relativism/interpretivism.
After his development of critical realism, Bhaskar went on to develop a philosophical system he calls dialectical critical realism, which is most clearly outlined in his weighty book, "Dialectic: The Pulse of Freedom".
An accessible introduction to Bhaskar's writings was written by Andrew Collier. Andrew Sayer has written accessible texts on critical realism in social science. Danermark et al. have also produced an accessible account. Margaret Archer is associated with this school, as is the ecosocialist writer Peter Dickens.
David Graeber relies on critical realism, which he understands as a form of 'heraclitean' philosophy, emphasizing flux and change over stable essences, in his anthropological book on the concept of value, "Toward an anthropological theory of value: the false coin of our own dreams".
Recently, attention has turned to the challenge of implementing critical realism in applied social research, including its use in studying organizations.). Other authors (Fletcher 2016, Parr 2015, Bunt 2018, Hoddy 2018) have discussed which specific research methodologies and methods are conducive (or not) to research guided by critical realism as a philosophy of science.
Critical realist meta-theories.
At its core, critical realism offers a theory of being and existence (ontology), but it takes a more open position in relation to the theory of knowledge (epistemology). As a result, a wide range of approaches have developed that seek to offer a framework for social research. Because they are not theories in specific disciplines nor theories relating to specific aspects of society, these approaches are generally known as 'meta-theories'. Critical realist meta-theories include: the transformational model of social activity, the morphogenetic approach, Cambridge social ontology, critical discourse analysis, cultural political economy, critical realist feminism, and critical realist Marxism.
The morphogenetic approach.
The morphogenetic approach is a critical realist framework for analysing social change originally developed by Margaret Archer in her text "Social Origins of Educational Systems" and systematised in a trilogy of social theory texts, "Culture and Agency" (1988), "Realist Social Theory" (1995), and "Being Human" (2000). The approach was developed primarily as a critical realist response to the structure-agency problem in which "we are simultaneously free and constrained and we also have some awareness of it". At the centre of Archer's answer to this problem is 'analytical dualism', which entails an analytical separation of structure and agency so that the interaction between them can be studied and modelled by researchers; on this basis, Archer rejects alternative approaches that 'conflate' structure and agency into the single concept of 'practice', primarily directing her critique at Giddens' structuration theory. Archer extends the notion of analytical dualism to the distinction between "the material and the ideational aspects of social life", identifying 'culture' as a third fundamental aspect of society, alongside structure and agency. Therefore, the analysis of social change depends on modelling structure (S), agency (A), and culture (C), so that "social life comes in a SAC – always and everywhere". These concepts form the basis for the 'morphogenetic cycle', which splits social change into three processes: [T1] "conditioning →" [T2-T3] "interaction" → [T4] "elaboration": 
The morphogenetic approach has been advanced by Douglas Porpora, whose "Reconstructing Sociology" sought to introduce morphogenetic critical realism into the mainstream of American sociology. Before becoming explicitly aligned with the morphogenetic approach and critical realism, Porpora published two papers on the nature of culture and social structure that later had a major influence on morphogenetic critical realism.
Cambridge social ontology.
Cambridge social ontology is an approach to ontology that is primarily associated with the work of philosopher Tony Lawson. The approach is centred on the Cambridge Social Ontology Group and its weekly Realist Workshop hosted by the University of Cambridge and led by Lawson. While the group subscribes to critical realism, it identifies its aims with the study of ontology more generally rather than a necessary allegiance with the critical realist philosophy. At the heart of the Cambridge approach is a theory of social positioning in which any social system creates roles (or 'places' or 'slots') that are occupied by individuals. Each of these roles is attached to a series of rights and obligations; for example, one of the rights of a university lecturer is the right to use a university library and one of their obligations to deliver lectures. These rights and obligations interlock to form social structures, so that the rights of an individual in one social position usually correspond with the obligations of an individual in another; for example, the rights of the lecturer might correspond to the obligations of a librarian. In some cases, it is not individuals that occupy these social positions but 'communities', which are defined as "an identifiable, restricted and relatively enduring coherent grouping of people who share some set of concerns". It is important to stress that these communities can exist at a wide range of scales, they are not necessarily attached to a particular geographical space, and they can overlap and nest in various complex ways. Therefore, individuals sit within social systems by occupying a role, and they sit within communities by sharing in the community's interests in some way. A final crucial concept of the Cambridge social ontology approach is the notion of 'collective practices': a collective practice is a way of proceeding that (implicitly) bears the status of being (collectively) accepted within a community. In other words, collective practices are common ways of acting in any given situation that are reinforced through conformity, such as the forming of queues to pay for goods in stores or the etiquette of a particular game or sport.
Critical discourse analysis.
Discourse analysis is the analysis of texts and other meaningful signs with the purpose of understanding and/or explaining social phenomena. "Critical" discourse analysis (CDA) is primarily concerned with analysing the relationship between discourse and social relations of power in any given context. In contrast to post-structuralist and postmodernist approaches to discourse analysis (such as the Essex school), CDA relies on philosophical distinctions between discourse and other aspects of reality, especially insisting on the relative independence of power relations, material existence and individual agency. While not all CDA explicitly ascribes to critical realism (see, for example the work of Ruth Wodak or Teun van Dijk), a critical realist ontology provides philosophical underpinnings for the social distinctions inherent to its approach to analysis. The main proponent of a critical realist approach to CDA is Norman Fairclough, whose philosophical underpinnings shifted from a Foucauldian perspective in his 1992 book "Discourse and Social Change" to an explicitly critical realist approach in his 1999 collaboration with Lillian Chouliaraki "Discourse in Late Modernity". Fairclough has subsequently published work developing the critical realist foundations of his version of CDA, particularly in collaboration with his Lancaster University colleagues Andrew Sayer and Bob Jessop. Fairclough explains how the main concepts of transcendental realism underpin his approach to the analysis of texts. Firstly, there is a distinction between the knowledge (the 'transitive dimension') and that which knowledge is about (the 'intransitive dimension'); this underpins the CDA distinction between discourse and other aspects of reality. Secondly, there is the distinction between experienced events (the 'empirical'), events themselves (the 'actual'), and the underlying mechanisms that give rise to events (the 'real'); this underpins the distinction between the reading of a text (the empirical), the text itself (the actual) and the causal structures underpinning the text's social effects (the real). While these critical realist distinctions are not commonly used in the empirical application of Fairlcough's CDA, they are fundamental to the underlying social theory that justifies its application. More recently, other theorists have further developed CDA's critical realist underpinnings by focusing on the distinction between structure and agency, the distinction between discourse and 'non-discourse', and the concept of social practices.
Cultural political economy.
Long-term collaborators Ngai-Ling Sum and Bob Jessop initially developed 'cultural political economy' (CPE) in a forum of the journal "New Political Economy," responding to the strict disciplinarity of existing approaches to political economy. CPE also has roots in Jessop's seminal collaboration with Norman Fairclough and Andrew Sayer, which outlined a critical realist approach to 'semiosis', the inter-subjective production of meaning. CPE is most extensively outlined in Sum and Jessop's 2013 book "Cultural Political Economy," where critical realism and the strategic-relational approach are identified as the twin foundations of the approach. These foundations lead to a central distinction at the heart of CPE between the 'semiotic and structural aspects of social