Emergent Properties Research Paper

1. The Philosophical Tradition Of Emergence

The concepts of emergence and emergent properties have a long philosophical tradition (see Stephan (1999) and Beckermann et al. (1992) for extensive reviews). Unanimously, the origins of the idea of emergence are attributed to John Stuart Mill (1974). Considered to be the classic source, Mill distinguished between two types of joint effect produced by the interplay of various causes (composition of causes). In the first type, the joint effect of several component causes is identical with the sum of the separate effects. With respect to the second type, the joint effect is heterogeneous to the separate causes. The properties of a system or a compound generated by the second type of joint effect were later to be labeled emergent. Offering an alternative to mechanism and vitalism, the 1920s may be regarded as the heyday of the philosophical tradition that grew out of Mill’s fundamental insight.

It was in this decade that those later to become classic authors—Samuel Alexander, Conwy Lloyd Morgan, Charles Broad, and Roy Sellars—published their influential works. According to Stephan (1999), ‘weak’ versions of emergentism may be distinguished from ‘strong’ ones. The former loosen some of the assumptions deemed to be essential for defining emergent properties in the latter versions. Both strands of theory assert that emergent characteristics of wholes are not the sum of the properties of their parts (nonadditivity). They cannot be understood by simply summing (or averaging) the behaviors of the constituents; rather, they must be described in terms of their own. The novelty thesis claims that in evolution genuinely novel (systemic) properties emerge. Examples are the advent of mind or reflective thought. In more abstract terms, this amounts to saying that emergent system properties are different in type from the properties of the system’s constituent components. The two strands differ, however, with regard to the core assumptions of emergence theory—deducibility and predictability of systemic properties. Strong versions maintain that emergent properties are not deducible or predictable from the properties of the constituents and their relations (nonpredictability and nondeducibility). In this view, emergence may be characterized as the antithesis of microreductionism (Auyang 1998). By contrast, in weak variants of emergence theory, all systemic properties that distinguish a system from the qualities characterizing its elements must be regarded as candidates for representing emergent properties. The late 1960s and early 1970s saw a renaissance of ideas of emergence. Centering around the fundamental issue of the mindbrain relationship—the psycho-physical problem— Bunge (1977) and Popper and Eccles (1977) offered theories strongly drawing on the idea of emergent properties.

2. Sociological Conceptualizations Of Social Reality

From its inception, sociological thought has been characterized by two dramatically different conceptualizations of social reality. In particular, these differences pertain to the fundamental understanding of the relationship between the individual and social organization. Methodologically, this problem may be couched in terms of the relation between the micro-and macro-levels—in other words, the micro–macro link. One tradition, most commonly referred to as the individualistic–reductionist position, asserts that the properties of the social at any level may ultimately be explained by the interplay between the properties of individuals (e.g., motives, preferences), who are the constituents of society. Having strong roots in the Scottish moral philosophers (David Hume, Adam Smith, Adam Ferguson), the development of twentieth-century social theory has been characterized by various attempts to explain social phenomena by the rules governing the behavior of individuals. Basically, this approach asserts that social organization results from individual actions. Fundamentally opposed to this view is the other sociological tradition, often classified as the collectivist position. Its basic assumption is that the social world constitutes a reality of its own. Historically, this position is closely intertwined with the demands of sociology as a young scientific discipline to claim its territory and to define its own true subject matter vis-a-vis already well-established disciplines. By asserting that society is a reality of its own, nonreducible to the rules governing individual behavior, sociology distinguishes itself especially from economics and psychology. Searching for the particular subject matter of sociology, proponents of this position asked about the novel qualities and the specificity of the social vis-a-vis other types of reality, such as the mental realm, the biological or physical realm. It is with this latter tradition in sociology that the ideas of emergence and emergent properties have been most commonly associated. For this reason, the historical development of the latter tradition is discussed below.

3. The Sociological Tradition Of Emergence: Society As An Emergent Property

In late-nineteenth and early-twentieth-century sociology, the ideas of emergent properties are reflected in the conceptualization of society as representing a reality of its own endowed with separate characteristics nonreducible to the properties of its constituents (i.e., individuals). The sociological tradition that incorporates this assumption strongly draws on the thesis of emergence as nondeducibility. In the early days of sociology, Emile Durkheim (1938) most prominently advocated this approach to the understanding of social phenomena. In Durkheim’s view, society is not solely the sum of individuals; rather, it is the association of individuals. Hence, it is the nature of this association that constitutes the decisive factors of social life and determines the proper characteristics of social phenomena (‘faits sociaux’). This theoretical stance was epitomized in the famous methodological rules introduced by Durkheim (1938) according to which the social realm needs to be explained by social phenomena.

In modern sociological thought, developed in the second half of the twentieth century, general systems theory has advanced to one of the most influential currents, implicitly or explicitly advocating ideas of emergence (Parsons 1937, 1951, Luhmann 1995). With the Durkheimian tradition, systems theory shares the fundamental methodological conviction of the nondeducibility of the social world. Social phenomena at different levels of social organization (i.e., society, organizations, social groups) show novel properties that cannot be explained by reducing them to the properties of and interactions between their constituents (i.e., behavioral properties of individuals). Hence, a genuine social theory is needed to account for social reality as an emergent property.

This line of thought, advocated by Durkheim in late-nineteenth-century sociology, was continued in the mid-twentieth century by Talcott Parsons, albeit with some major modifications (Parsons 1951). For Parsons, the old problem raised by Hobbes about the origin of social order and social integration constitutes the fundamental sociological issue to which social theory needs to provide a satisfactory answer. The core of Parsons’ answer to this fundamental problem is his thesis on the independence of institutionalized values and norms vis-a-vis the reality of individuals. The common system of ultimate values, constituting a reality sui generis, helps to establish order at various levels of social life and to prevent a free-for-all. In essence, Parsons declares commonvalue integration as the emergent property of social action systems. Parsons derives this conclusion from his systems-theoretical approach to the relationship between individual actors and social organization, whereby the starting point is the assumption that all reality realms constitute systems (i.e., the biophysical, personality, cultural, and social systems). Despite fundamental differences between various types of systems, they all share the system character as a common feature. By drawing a sharp distinction between the social system (the social reality) and the personality system (the human being), Parsons maintains that each system needs to solve its own particular functional problem (i.e., system stability), for which each system relies on self-regulating mechanisms. In the case of the social system, social order and social integration are the functional problems, and processes of socialization and social control are the self-regulating mechanisms. Despite their own system logics, the two systems interact with each other in such a way that each system constitutes the environment for the other. The interactions between systems and their environment include the mutual exchange of resources, necessary for each system to keep up its functional capacity (i.e., system maintenance). Within this systems-theoretical framework, the social system and the personality system mutually presuppose each other; they are of equivalent status. This implies that there is no ontological priority of one system over the other. Hence, the properties of the social world cannot be deduced from the rules governing the personality system. The society is thus an emergent property.

Within the tradition of systems theory, Niklas Luhmann (1995) has provided the latest elaborate attempt to conceive of social reality as a separate, nonreducible system, reproducing itself solely on the basis of its own elements. Sharing some common ground with Parsons’ theoretical approach, Luhmann designs a systems theory that makes use of fundamental ideas developed in molecular biology. In particular, Luhmann applies the concept of autopoiesis advocated by Maturana to social reality. Arguing at a very high level of abstraction, social systems are autopoietic systems in as much as they are self-reproduced by their own components, which are defined as acts of communication. This amounts to saying that social systems operate on the basis of communicative acts engendering subsequent acts of communication. Hence, the social system is an independent, self-reproductive whole. Like Parsons’ theory, Luhmann’s approach attributes great significance to the strict distinction between the social system and the psychological system. These two separate systems reciprocally constitute the environment of the other, for any system needs appropriate environmental relations for its self-reproduction. Given the system– environment relationship, the autopoiesis of the social system is not conceivable without the autopoiesis of the psychological system and vice versa. In other words, the two autopoietic systems enable each other to operate. From this it follows that the two systems are equivalent (and not hierarchically dependent), which precludes the reductionist assumption that systemic properties of one system can be deduced from those of any other system. Consequently, social systems are emergent properties.

4. The Renaissance Of Ideas Of Emergence In Late-Twentieth-Century Theoretical Thought

In the latter part of the twentieth century, ideas of emergence have again attracted considerable attention in various scientific fields. Several new approaches, such as synergetics (Haken 1978) and other versions of self-organization theory (Krohn and Kuppers 1992, Krohn et al. 1990) or chaos theory (Newman 1996), address interdisciplinary research questions at a relatively high level of abstraction that allude to problems raised in classical emergence theory. Examples of these research problems are the investigation of the spontaneous and self-confined emergence of new structures and systemic properties or the examination of predictability in chaotic dynamic processes. Interestingly enough, this body of research seldom refers to the tradition of emergence theory and the notion of emergence itself remains rather vague. This suggests that, for these theoretical approaches, the concept of emergent properties is used less as an analytical research tool and more as a guiding research idea.

This is most apparent in the booming field of theories of self-organization. Krohn and Kuppers (1992), for example, provide a rather vague concept of emergent properties. They define emergence as the sudden appearance of novel properties that can be explained neither by the properties themselves nor by the relations of the elements involved, but rather by specific self-organizing process dynamics. To complicate matters, the notion of self-organization is also a shifting concept. Depending upon the strand of system theory, the meaning attributed to self-organization turns out to be completely different. Searching for the least common denominator, self-organization may be understood as interactions between the components of a system and its organization that lead to modifications on both sides (Hejl 1990, p. 115). It follows that the dynamics of self-organization engender new structures endowed with emergent systemic properties. In theories of self-organization then, self-referential organization of systems and emergent properties are causally related. Within this theoretical framework, social phenomena, such as social networks and social movements, easily lend themselves to the conceptualization of emergent properties generated by self-organizing process dynamics.

The issues addressed in theories of self-organization discussed above may be generalized to include the problem of how to conceive of the relationship between microinteractions and macrostructures—in short, the micro–macro link. With respect to social theory, the great bulk of previous work adheres to either a bottom-up method (microreductionism) or a top-down method (systems theory). Both methods, taken by themselves, have their limits. The reductionist tradition in social theory must at least acknowledge systemic properties as marginal conditions of individual behavior. Vice versa, the collectivist tradition is often short of explaining many systemic properties. Against this background, the need for a circular movement of theory building when conceptualizing the micro-macro link (i.e., interlevel explanations) is evident. Hence, approaches that attempt to couple systems concepts with constituent concepts are in demand. A theoretical framework of this type ‘simultaneously accounts for the behaviors of systems on one organizational level, the behaviors of their constituents on a lower level, and the relations between them’ (Auyang 1998, p. 5). In this respect, the approach of synthetic microanalysis proposed by Auyang (1998) may be regarded as one example.

5. Emergent Properties: Methodological Issues

Methodologically, the question arises of how to assess emergent properties. The key to answering this question lies in the exploration of the link between the micro and macro levels of social phenomena. From this perspective, the claim that the whole is more than the sum of its parts amounts, first, to furnishing proof of the specific assumptions implied in either the ‘strong’ or ‘weak’ versions of emergence theory (see Sect. 1). According to the ‘strong’ version, properties at the higher levels of aggregation (i.e., the macro level) qualify as emergent, if they cannot be deduced or predicted from the properties of units at lower levels (i.e., the micro level). In the ‘weak’ version, they qualify, as long as they can be expressed as complex functions of the lower level characteristics. Second, the assessment of emergent properties must be based on evidence regarding the impact of system properties (i.e., contextual properties) on lower-level units and or relationships that operate independently of the effects of any lower-level characteristics. Couched in more technical terms, the second requirement implies that the attributes of units operating at the micro level are a function of context (i.e., the macro level). The two tasks identified here to assess emergent properties address a measurement issue on the one hand and an issue about modeling techniques on the other. Each issue will be addressed in turn.

5.1 The Measurement Issue

‘Strong’ and ‘weak’ versions of emergence theory agree that higher-level properties that can be expressed as simple functions of lower-level attributes do not qualify as emergent. Examples include contextual characteristics defined as the sum, as a proportion or as the mean of lower-level properties (e.g., percentage of community residents above the age of 65 years; average income of regions). The two strands of emergence theory differ, however, with regard to the theses of deducibility and predictability. The ‘strong’ version claims that emergent properties are global attributes that are not expressible as functions of lower-level properties. This implies that system properties need to be measured at the system level as opposed to the level of system elements. One example of such an approach would be the description of political systems characterized by the degree of corporatism, whereby the measurement of corporatism would be based on expert judgement.

The measurement issue involved in ‘weak’ versions of emergence theory includes the application of complex rules of aggregation. Expressed as complex functions of lower-level attributes, system properties can be deduced or predicted from lower-level units. The income distribution characteristic of regional contexts—expressed by a complex function of individual incomes—serves as an example. A methodological perspective that is well suited to identifying emergent properties in line with ‘weak’ versions of emergence theory is network analysis, most prominently advocated by scholars such as Ronald S. Burt, Mark Granovetter and Barry Wellmann. This technique truly addresses the fundamental idea of the whole being more than the sum of its parts by focusing on relational characteristics and by introducing complex rules of aggregation. The social closure of elites, for example, cannot be inferred from the attributes of individual members of the elite. It is a property inferred from the relational attributes of the network members. Hence, the relational order of network elements (i.e., the structure) is a system property that truly qualifies as an emergent property. The second basic assumption of network analysis is the embeddedness of lower-level units in higher-level systems (i.e., networks) (see Granovetter 1985). This implies that lower-level outcomes (e.g., preferences, tastes, action orientations, performance at the individual level) are mediated by higher-level system properties. This is to say that individual and collective actors respond to their social context. Couched in more technical terms, the notion of embeddedness addresses the issue of the additive and interactive effects of context on lower-level outcomes. This remark leads up to the second issue raised above, namely the modeling techniques required to assess emergent relationships.

5.2 The Impact Issue

To assess the effects of system properties measured at various levels of a hierarchical structure on lower-level outcomes, multilevel models (or contextual models) are the method of choice. A variety of models are used to specify the link between the macro and micro levels of social phenomena. While the names of the models and their statistical properties do differ (e.g., hierarchical linear model, random coefficients model, hierarchical mixed linear model), the basic idea is ‘to analyze data that consist of multiple macro units (contexts) and multiple micro units within each macro unit’ (DiPrete and Forristal 1994, p. 334). Within these models, two types of effect can be distinguished: main or additive effects and interactive effects. Main effects of higher-level properties on lower-level outcomes (e.g., behavior) provide evidence that context matters over and above the impact of any lower-level attributes. This indicates that the relationships identified through the effect analysis cannot be reduced to individual differences. Examples of substantive research along these lines include the contextual effects of schools and classes on student achievement or the impact of macro contexts, such as organizational structure and labor market segmentation, on career outcomes. The second type of effect involves interaction effects of properties measured at various levels of a hierarchical structure. The existence of cross-level interaction effects provides evidence of how higherlevel properties (i.e., the macro context) affect the impact of lower-level attributes (i.e., those at the micro level) on the outcome of interest. Variation in the strength of the effect of micro-level properties on the outcome when system properties are included indicates the presence of relationships that can be qualified as emergent. The reason is that interaction effects involving cross-level components show that they are more than the sum of their parts. Substantive research employing this complex modeling strategy includes, for example, the ways in which country characteristics (e.g., economic development; policy programs) affect the influence of maternal education on the reproductive behavior of women.

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