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 actualised 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/Falsificationism are also rejected due to the observation that it is highly plausible that a mechanism will 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 positivists) be taken to signify its non-existence.
Critical naturalism argues that the transcendental realist model of science is equally applicable to both the physical and the human worlds. However, 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 method which seeks 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.
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. An edited volume examined the use of critical realism for studying organizations (Edwards, O'Mahoney, and Vincent 2014). Other authors (Fletcher 2016, Parr 2015) have discussed which specific research methodologies and methods are conducive (or not) to research guided by critical realism as a philosophy of science.
Heterodox economists like Tony Lawson, Lars Pålsson Syll, Frederic Lee or Geoffrey Hodgson are trying to work the ideas of critical realism into economics, especially the dynamic idea of macro-micro interaction.
According to critical realist economists, the central aim of economic theory is to provide explanations in terms of hidden generative structures. This position combines transcendental realism with a critique of mainstream economics. It argues that mainstream economics (i) relies excessively on deductivist methodology, (ii) embraces an uncritical enthusiasm for formalism, and (iii) believes in strong conditional predictions in economics despite repeated failures.
The world that mainstream economists study is the empirical world. But this world is "out of phase" (Lawson) with the underlying ontology of economic regularities. The mainstream view is thus a limited reality because empirical realists presume that the objects of inquiry are solely "empirical regularities"—that is, objects and events at the level of the experienced.
The critical realist views the domain of real causal mechanisms as the appropriate object of economic science, whereas the positivist view is that the reality is exhausted in empirical, i.e. experienced reality. Tony Lawson argues that economics ought to embrace a "social ontology" to include the underlying causes of economic phenomena.
A development of Bhaskar's critical realism lies at the ontological root of contemporary streams of Marxist political and economic theory. The realist philosophy described by Bhaskar in A Realist Theory of Science is compatible with Marx's work in that it differentiates between an intransitive reality, which exists independently of human knowledge of it, and the socially produced world of science and empirical knowledge. This dualist logic is clearly present in the Marxian theory of ideology, according to which social reality may be very different from its empirically observable surface appearance. Notably, Alex Callinicos has argued for a 'critical realist' ontology in the philosophy of social science and explicitly acknowledges Bhaskar's influence (while also rejecting the latter's 'spiritualist turn' in his later work). The relationship between critical realist philosophy and Marxism has also been discussed in an article co-authored by Bhaskar and Callinicos and published in the Journal of Critical Realism
Since 2000, critical realist philosophy has also been increasingly influential in the field of International Relations (IR) theory. Patrick Thaddeus Jackson has called it 'all the rage' in the field. Bob Jessop, Colin Wight, Milja Kurki, Jonathan Joseph and Hidemi Suganami have all published major works on the utility of beginning IR research from a critical realist social ontology - an ontology they all credit Roy Bhaskar with originating.