Theories
of Citation ?
Scientometrics 43(1), 1998, 5-25
Loet
Leydesdorff
Science
and Technology Dynamics
Nieuwe Achtergracht 166
1018 WV Amsterdam
The
Netherlands
Abstract
Citations support the communication of specialist
knowledge by allowing authors and readers to make specific selections in
several contexts at the same time. In the interactions between the social
network of (first-order) authors and the network of their reflexive (that is,
second-order) communications, a sub-textual code of communication with a
distributed character has emerged. The recursive operation of this
dual-layered network induces the perception of a cognitive dimension in
scientific communication.
Citation
analysis reflects on citation
practices. Reference lists are aggregated in scientometric analysis using
one (or sometimes two) of the available contexts to reduce the complexity:
geometrical representations (‘mappings’) of dynamic operations are reflected in
corresponding theories of citation. For example, a sociological
interpretation of citations can be distinguished from an
information-theoretical one. The specific contexts represented in the
modern citation can be deconstructed from the perspective of the cultural
evolution of scientific communication.
‘By now, it may seem redundant to say
that a theory of citation is badly needed.’
Zuckerman (1987)
1. Introduction
Citation analysis has been a
formative instrument of scientometrics as a subject of study for several
decades. The primary impulse to organize citations into a Science
Citation Index came, however, from information retrieval. Eugene
Garfield (1979, at p.7) was inspired by the American system of legal
documentation. In an early phase, Derek de Solla Price joined the
citation project: he associated the data of the SCI with measurement
techniques. Concepts like ‘mapping science’ by studying the dynamics of
citation networks were introduced (e.g., Price 1965; cf. Wouters 1998).
Notwithstanding serious attempts
in this direction (e.g., Small 1978), a complete theory of citation is still
lacking. In 1981, two authors raised this problem independently, yet from
different perspectives: Cozzens (1981) provided a review of citation theories
from the perspective of sociology, and Cronin (1981) asked for a theory of
citation from the perspective of information retrieval. In his ensuing
monograph, Cronin (1984) discussed citation as a function in scientific
communication among texts. In citation context analysis (e.g.,
Chubin and Moitra 1975; Moravcsik and Murugesan 1975), the theory of citation
had until then been developed mainly with reference to the uses of citations within
articles.
Others (e.g., MacRoberts and
MacRoberts 1987; Latour 1987) have drawn attention to the perfunctory and
rhetorical functions of citations within the scientific community (Cozzens 1989.)
Evaluation studies for science policy purposes have considered citations as an
indicator of reward in the science system (Martin and Irvine 1983; Moed et
al. 1985; Luukkonen 1990; cf. Merton 1968; Latour and Woolgar 1979).
Furthermore, new scientometric indicators such as ‘co-words’ were introduced in
the 1980s (Callon et al. 1982). While ‘co-citation maps’ were
interpreted as representations of perceptions by citing authors (Small 1973;
Small and Griffith 1974; cf. Small 1978), co-word analysis provided us with
representations of semiotic networks among these authors (cf. Callon et al.
1986). In summary, a variety of theoretical contexts for citation analysis was
proposed, but a comprehensive theory of citation itself could not be
formulated.
The variety of indicators made
scientometricians aware that citations are specific, yet they share some
properties with other textual indicators. Citations refer to another
word, phrase, sentence, paragraph, or title of text from the perspective of the
citing article. While in the case of co-word and co-citation analysis the
relation is constructed by the analyst, the citation is provided as a link
between two documents by the citing author him/herself. Citation is in
this sense not a scientometric indicator; scientometric analysis is
based on a careful reconstruction of citation practices using, for example, the
Science Citation Index as a database (Kaplan 1965; cf. Wouters 1997). In
practice, however, the meaning of citations seems easier to understand intuitively
than that of analytically defined codes in scientific texts (Snyder et al.
1995). Furthermore, citations are an order of magnitude more specific than, for
example, shared (co-)words (Leydesdorff 1989). Citations thus seem to have
specific functions in the research process (Garfield 1996).
In this study, I argue that
citations as currently understood emerged during a certain phase of the
scientific development in physics, namely in the early 20th century. The
historical deconstruction of the citation in terms of interacting networks of
authors and texts will enable me to suggest a new theory of citation as a
dynamic operation that allows for reduction of complexity in various contexts
at the same time. The dynamic perspective of selections operating upon
selections in other networks accounts for the character of citations as
statistical (i.e., uncertain) indicators, for their specificity, and for their
multi-contextuality. A reappraisal of existing theories of citation
becomes possible, and thus an opening to the discussion among citation analysts
can be suggested.
2.
Analytical distinctions
Citation analysis itself
considers the use of citations in scientific literature as a practice, and the
articulation of a theory of citations has remained firmly on the agenda of
scientometrics. While scientometric indicators can be defined as formal
methodologies, the citation process is social, and therefore challenges the
substantive understanding: under which conditions can citation be used as a
measure of impact, quality, relevance, reputation, etc.? How do insights
from various disciplines contribute to our understanding of the epistemological
process and the working mechanism of citation in science? Why has
citation as a social act held such a prominent position in the generation of
knowledge? Or is this very statement a distortion with hindsight from a
citation analyst’s perspective (Edge 1979)?
Let me introduce some analytical
distinctions. The quest for a theory of citations presumes that citations
themselves should be explained. First, however, one may wish to raise the
question of whether citations belong to the explanandum-that
is, the subject to be explained-or to the explanans-that
is, used to explain something else. If citation analysis is primarily a
tool for explaining, for example, the growth of science, can then a ‘theory of
citation’ be nothing more than a methodological reflection designed to improve
the accuracy of this measurement?
In my opinion, citation analysis
is regularly used as a tool or an indicator within an explanans.
A lack of theoretical clarity about what is to be explained by using citation
analysis is almost unavoidable if the focus is-as often happens in scientometric
studies-on improving the tool without theoretical attention to
the specification of the explanandum. A problem formulated in a
policy context does not always need to be elaborated theoretically. A
narrative interpretation of the mappings may suffice (cf. Glänzel et al.
1996). Differences between mappings can be studied fruitfully as
validation problems (Leydesdorff 1987; 1989; 1992; cf. Van Raan 1988).
But when one raises questions
like whether citations indicate ‘quality’, ‘impact,’ ‘status,’ etc., one is in
need of a clear definition of these concepts with reference to units of
analysis. Is it the quality of an author or an institution, or the
quality of articles themselves that is implied? Is one type of mapping
more suitable than another for exhibiting one or another type of quality?
The functions of citations are expected to be different when different contexts
or different levels of aggregation are studied (Leydesdorff and Amsterdamska
1990).
2.1
Citation as explanandum
Let us first focus on ‘citation’
as something to be explained (explanandum) because this specification is
an initial step toward the articulation of a theory of citation in the proper
sense. What actually are citations? As noted, citations are
references to another textual element, from the perspective of the citing
article. In order to have citations, there must be a cited-citing
pair. From a formal perspective, cited-citing pairs are relations.
By adding a dynamic perspective, these relations can be considered as
relational operations.
The relational operation is
recursive: for example, citations may refer to other texts in which citations
refer to still other texts. Thus, a network of citation relations is
spanned at each moment in time and reproduced over time. The network, resulting
from this repeated operation is expected to have an architecture.
Therefore, citations have a position in a multi-dimensional space
constituted by other citations. Two operations can be close in terms of
position without having a relation or without sharing a common relation (Burt
1982). An operational relation is able to function in a network because
of its position. Operations are expected to be reproduced if they carry
functions. Thus, one has to specify the functionality of the citation
process.
The functionality is understood
to be embedded in the distribution (Maturana and Varela 1980). While citations
can be observed as specific events, they acquire analytical meaning only in
terms of distributions: why was this citation used and not another? Actually,
citations occur usually in groups, that is, as lists of references.
Citation analysis studies the traces of the operation of this distributed
network system. Citations are then observed at the nodes of the network
(that is, within texts), whereas the recursive operations at the network level
remain hypotheses about their cognitive functions. One is able to
reconstruct only analytically this cognitive structure, for example, in terms
of an ‘eigenstructure’ of the dual-layered network. From this
perspective, the observables test the theoretically informed expectations about
the network’s structure, and thus, cognitive assumptions are changed or
reinforced.
The operation is additionally
dynamic: the distributions exhibit the patterns and structures of expectations
for further operation. Thus, the process of new knowledge claims is
propelled and made more precise and selective. The dynamic aspect is of
the utmost importance: even when the links of a network are stabilized-as
in the case of telephone lines-the frequency of the operation over the lines
can still be distinguished analytically from the observable carriers. The
function of citations in propelling the networks of substantive knowledge
contents is different from, yet constrained by their propagation through
networks of textual and social relations.
I wish to argue that this
multi-dimensional network is dually layered: citations are the result of the
interaction between networks of authors and between networks of their
communications. Thus, the modern citation is constitutionally complex,
and therefore it can function in scientific practices by indicating both the
cognitive and the social contexts of a knowledge claim. At a generalized
level, citations, as potentially repeated operations, sustain communication in
the sciences by drawing upon cognitive and social contexts.
The scientific publication which
makes the citation can then be considered as an event: each publication potentially
redistributes citation patterns, although the change in the overall
distributions may be marginal. Thus, the subtext of a communication
pattern can be communicated in a complex way among networks of authors and
texts. Citations, however, are neither a necessary nor a sufficient
condition for scientific communication. While nowadays they help to
sustain the communication, the process of their codification has varied across
fields of science (Price 1970). Citations did not emerge historically with
scientific literature at the time of the scientific revolution. They
emerged from the specific organization of the sciences in the late 19th
century.
Of course, authors have always
made references. The scholastic tradition of the Middle Ages, for example,
can be typified by its tendency to comment on previous generations of authors
(especially, Aristotle). The reference implies an implicit citation, but
these citations were not to contemporary colleagues with whom one could dispute
the interpretation of a text; the reference was rather to the text under
discussion. In a religious society of the monotheistic type, every text
is essentially a further explanation of the original text, like the Bible or
the Koran. Thus, scholastic authors had to legitimate their contributions
within their tradition (e.g., Weinberg 1997).
In modern sciences, references
have a different function. A new knowledge claim adds to the scientific
literature by drawing a further distinction (Luhmann 1990, pp. 75 ff.).
Some citations serve to indicate where and when a new distinction can be drawn,
and may indicate how such a knowledge claim can be reintegrated into a body of
theorizing. Because of the recursivity involved, citations exhibit the
collective character of scientific achievements at each moment in time.
At the time of the scientific revolution, Newton expressed this collective
character of the modern scientific enterprise with his well-known aphorism: ‘If
I have seen further, it is by standing on the shoulders of giants’ (Merton
1965). These giants were scholars like Galileo, Kepler, and Huygens, with
whom Newton sometimes communicated personally or in writing. Circles of
correspondence among leading scientists were organized by Mersenne (1588-1648)
in Paris and Oldenburg (1615-1677) in London (Kronick 1991).
In 1665, the first volume of the Philosophical
Transactions of the Royal Society was published, soon to be followed by the
French Journal des Sçavants.[1] Note that these journals were no
longer published in Latin, and that they were secular publications. The
circles of communication among these ‘learned gentlemen’ were small, and
science was not yet institutionalized. Their references to one another in
the texts (1665-1800) are made in the polite form of ‘M. Huygens’, ‘Mr. Hook’
or ‘Signior Rizetti’. Typically, Jean T. Desaguliers comments at p. 610
of Volume 35 of the Philosophical Transactions:
This must have been Signior Rizetti’s mistake . . . for several of the
Persons present at my Experiments made the same Mistake at first before they
could perform the Experiment in manner above-mentioned.
The ‘M.’, which stands for
‘Monsieur’, is still available as a form of communication among authors in
French scientific literature.
Science in the 18th century was
largely based on personal communications. The 19th century witnessed the
further institutionalization of science and scientific communication. For
example, the Proceedings of the Royal Society began to appear from 1800
onwards. In Prussia’s Humboldt University (after 1815) research joined
education as a major function of the university. Thus, the holding of a
Chair in an institute became a crucial factor for career opportunities in
science. In short, science became an institutionalized social system
(Stichweh 1984).
By 1800, the codification of the
legal system had provided formats for systematic and depersonalized
communication: legal and material rights can be distinguished when natural law
is formalized into positive law (Weber, 1922, pp. 503 ff.; Habermas 1981, pp.
351 ff.).[2] Further institutionalization and growth of science during
the 19th century made it increasingly possible to communicate also in this
context with texts that were indicated by personal names, yet without primary reference
to specific individuals. The individual scholar increasingly becomes the
carrier of a knowledge claim in a network of communications among
scholars. The claim itself can be debated, irrespective of the author,
his or her institution, the quality of his or her oeuvre, etc.
During the whole 19th century,
references remained firmly attributed to authors-as opposed to identifiable and
precisely dated texts. Bazerman (1988) has extensively studied the modern
citation as an innovation of the early 20th century using Physical Review
as his source material. With reference to the 1890s, he noted:
The lack of concern with dating references, and the age of the references that
are dated, further weaken the sense of a coherent, moving research front.
In both 1893-95 and 1900-1901 (Bazerman’s sample years, L.), 52 percent of the
references are undated, and only about 30 percent are dated six years or less
from the article’s publication.
By 1910, the number of references per article has decreased dramatically to
only 1.5, and the few references are dated and of recent vintage, suggesting
immediate relevance for the work at hand. (Ibid., pp. 165f.)
After 1910 the number of (dated) references per article increased
rapidly, and the modern citation became a specific layer of communication in
and among scientific texts. The citation from then onwards can be
considered as a concept-symbol (Small 1978) instead of a reference to a
person’s oeuvre (cf. Meadows 1974, pp. 83 ff.). In his historical
exercise to construct a Physics Citation Index, Small (1986) analyzed
the 1920s. This is the period in which citations could for the first time
be aggregated because of the further development of the modern format.
Note the novelty of the transition: the interaction between a
second-order layer of reflexive communications among (first-order) authors
provides the condition for the generation of a more abstract cognitive
structure of concept-symbols. The dual-layered network system of (1)
social relations among scholars and (2) relations among communications is
expected to resonate dynamically on the basis of interactions in some
directions, while not in others. The structural dimensions of this
complex network are partially correlated to individual authors as carriers of
the communication, as they are also correlated to the textual dimension of the
knowledge content (Leydesdorff 1995). The interactively emerging
dimension itself remains latent while it develops, and thus a strategic vector
is induced that can be recognized (cf. Abernathy and Clark 1985). The
recognition recursively assumes and refines cognition within the observing
systems (Maturana and Varela, 1980).
Over time, this operation becomes thoroughly selective on both sides:
citations are sometimes ‘obliterated by incorporation’ (OBI) into the body of
knowledge,25 and social factors may temporarily play a role for further
selections, e.g., in terms of reputations. In principle, two selective
layers operating upon each other tend to extinguish the signal. However,
at some places the two distributions may happen to ‘lock-in’ because a third
(that is, cognitive) dimension can be carried further by a specific combination.
In this co-evolution between communications and authors, distributions
of citations may function, among other things, as contested boundaries between
specialties. Since citations are distributed, the boundaries remain to be
validated (Fujigaki 1997). Functions are expected to change when the
research front moves further. By using references, authors position their
knowledge claims within one specialty area or another (Amsterdamska and
Leydesdorff 1989). The implied social and cognitive dimensions enable
practicing scientists to use citations as an instrument for retrieval.
Some selections are chosen for stabilization, for example, when codification
into citation classics occurs (Small 1974; cf. Garfield 1979). Some
stabilizations are selected for globalization, that is, when ‘tacit’ knowledge
is accepted at a super-systemic level (Merton 1965, pp. 218 f.).
As the complex network is further shaped, citations allow for richer
communications since both social and cognitive factors can be incorporated into
the progression of the sciences. A reference to a codified citation
provides a shorthand for not having to explain a method or another intellectual
tool (Garfield 1979, p. 246). The meaning of this reference has then
become stabilized within a specific scholarly community, while intellectual and
social boundaries are reinforced by readers familiar with the reference (cf.
Whitley 1984). In summary, the historical origins of the epistemological
function of citation as a social practice are to be found in this distributed
and dual-layered operation. The dual-layeredness of the distribution
induces the dynamics, since selections operate on selections. Yet the
cognitive principle of referencing, once historically invented, had still to be
diffused and then to be institutionalized.
This codification of science as a network of reflexive communications on
top of a first-order network of social relations among scientists is a
historical process that is also reflected in other ways. Not until the
late 1960s did philosophers and historians of science like Price (1965) and
Kuhn (1962/ 1970) begin to be able to understand science as an order emerging
from networks of communication relatively independent of carrying authors
(Garvey 1979). Price (1961), for example, noted the emergence of abstract
journals during the 19th century as shown in his well-known graph reproduced in
Figure 1. Once the number of scientific journals had exceeded a few
hundred, higher-order codification became a condition for the further growth of
knowledge. One could no longer rely on selections by individuals;
networks of communication based on the interactions between people and journals
ease the reproduction of the system by taking over selective functions at an
above-individual level.
Figure 1 Total number of scientific journals and abstract
journals founded, as a function of date. From: Price (1961). |
Social factors also have played a
role in these historical transitions, like the cheaper production of paper when
cotton became available to the textile industry on a large scale (Gouldner
1976). Social contexts provide the resources for taking the next steps in
the cultural evolution of the sciences (Barnes and Edge 1982; Leydesdorff
1997). The codification of science, its disciplinary differentiation
(Stichweh 1990), and its institutionalization in the Humboldt-type universities
(Jencks and Riesman 1968) made it necessary to develop new styles of
referencing that honour science as a social enterprise and in terms of
concept-symbols more abstract than authors’ names. Thus, the modern citation
was born as a code and a medium of communication in the early 20th century.
2.2
From Citations to Citation Analysis
It was well into this century
before the philosophy of science was able to achieve an understanding of
‘truth’ as an attribute no longer of a (personal) idea, but of a communicative
statement. Citation could not be a major focus in this new philosophy of
science, because the citation indicated a relation with science as a practice
(that is, Popper’s ‘context of discovery’). Only in a context like that
of science studies as an interdisciplinary area (e.g., Spiegel-Rösing and Price
1977) can citation analysis be a legitimate subject of study.
Citation analysis, thus,
reflects another turn of the tables. After World War II, science had
grown so expensive and so differentiated in disciplinary organization that new
instruments were needed for its managerial control. From within the
scientific institute, information retrieval posed a new challenge. At the
level of society, Vannevar Bush’s The Endless Frontier (1945) should be
mentioned here. In this Report to the President, Bush requested
political support for fundamental research, that is, as a separate domain of
social organization and state intervention. Indeed, the late 1940s and the
1950s witness what can with hindsight be called ‘the institutional phase of
science policy’ (e.g., Spiegel-Rösing 1973). Since the 1950s, funding
acknowledgements and institutional addresses regularly appear in scientific
publications (Gillmore 1986, p. 115; cf. Rip and Hennekam 1985). In this
context of science management and scientific information, citations can be used
as proxies (Adair 1955; Garfield 1955).
Citation indexing inadvertently
changes the system of reference for citation analysis. While citations
can be used to trace intellectual influence and to retrieve information by
taking the cited text as a lead to follow the history of a knowledge claim
(Latour 1987), the construction of an index inverts the time axis (Wouters
1997). In citation analysis, citations are counted from the citing texts, and
thus cited texts are provided with authority by hindsight (Garfield
1979). This reflection changes the model from a historical to an evolutionary
one: older texts constitute variations which compete for citations in ‘current
contents.’ The analytical focus of citation analysis is on selection in
the present: the operation is foregrounded. Therefore, stabilization and
codification have now to be explained. Note the contrast with citation of
the Bible for scholastic reasons.
Whereas citation is an emerging
(reflexive) practice, citation analysis implies a reflexive theory. While
this theory has not (yet) been articulated, the field may seem to be driven by
measurement problems. However, the operation is entirely theoretical:
citation analysis reconstructs scientific development in an evolutionary mode
with reference to scientific developments which are themselves being
continuously reconstructed. All the empirical sciences reflexively rewrite
their histories in the light of new evidence. The implied evolutionary
understanding of science is reinforced by citation analysis.
This implication is also part of
the reflexive rewriting of the history of scientometrics as a field of
science. What have citations meant for our specialty? While
citations are used by historians to track developments of the sciences,
citation analysts reconstruct history from a perspective in the present.
A theory of citation becomes urgent when this perspective is understood as a
cultural construct itself (Mulkay et al. 1983). Because it is
possible to change perspectives, a scientific text no longer has an inherent
and a priori value. Each knowledge claim can be provided with a
revised function during the further evolution of the distributions.
Different functions can be equally valid or valid at different moments in
time. A distribution of functions can be distinguished, and so the
functions become uncertain and reflexive expectations.
The same authors can be cited
because of different knowledge claims. The unit of analysis for citation analysis
is the scientific paper, unless specified otherwise (e.g., White and
Griffith 1981). From an evolutionary perspective, the author can be
considered as the retention mechanism of the credit that is attributed to a
text by a citation. When credit has accumulated (Latour and Woolgar
1979), the result may be incorporation into codified knowledge by obliteration
(Cozzens 1985), or even by ‘eponymy’-that is, attaching a name to a phenomenon like
the ‘Zeeman-effect’ (Merton 1957). The retention mechanism feeds back on
the citation cycles as one of its reflexive subdynamics.
In a social system, the retention
mechanism for social accomplishments is usually the institution. However,
the institution can be considered as yet another distribution of actors.
By taking this uncertainty as unit of analysis, emerging discourse of science
& technology policies has been able to intrude into the circle of reflections
on scientific discourses (Woolgar 1991). In citation analysis, this
potential opening has been recognized by paying increasing attention to
institutional addresses. Much effort in the 1980s, indeed, has gone into
‘cleaning up’ the Corporate Index of the Science Citation Index because,
from a science policy perspective, individuals are less interesting units than
institutions. Nowadays, the CD-ROM version of the Science Citation
Index enables the analyst to search the institutional addresses for precise
postal codes.
Citation analysis allows for
choosing institutional frameworks as another perspective for aggregation (e.g.,
Martin and Irvine 1983; Moed et al. 1985). In other words, the
unit of analysis can be varied. Different rules of aggregation, however,
refer to different dynamics, and therefore the specification of different
theoretical reflections is expected. Note that one has a dual problem in
citation analysis: the unit of analysis can be either text or author, and the
level of aggregation may vary. Elsewhere51 we defined the dimensions of
citation analysis at the micro-level by using the following
cross-tabling:
|
Citing Author |
Citing Text |
Cited Author |
Professional Relation |
Reward |
Cited Text |
Cognitive Resource |
Discursive Relation |
Table 1
Possible
functions of citation relations at the disaggregated (micro) level
The specifications at the
micro-level refer to (aggregated) systems that generate specific hierarchies and
dynamics by operating in a distributed mode, that is, in terms of
micro-events. The various (sub‑)systems participate in each
citation to a greater or lesser extent by interacting. Rewards, for
example, tend to help stratify the system into social hierarchies, journals
help to structure the communication, while cognitive resources are aggregated
in terms of more abstract categories like theories. Each event is a
micro-operation, but the distributions of these interactions can be organized
along different axes. This can be reflected using corresponding theories.
Analogously, I propose the
following cross-table for the aggregated level of citations:
|
Citing Groups |
Citing Document Sets |
Cited Groups |
social networks |
hierarchies |
Cited Document Sets |
concept symbols |
codification |
Table 2
Possible
functions of citation relations at the aggregate level
The relation between the micro-
and macro-level of analysis introduces the dynamics of reproduction into each dimension
as yet another research question. One expects networks to be reproduced
in a distributed mode but at specific locations (Maturana and Varela 1980;
Rumelhardt et al. 1986). In this manner, a network with a
structure is generated. This dynamic problem has been discussed by
sociologists in terms of action/structure contingency relations (Giddens 1984;
Luhmann 1990; cf. Leydesdorff 1993). While theories about these complex
static relations tend to be formulated in terms of geometries (that is, in terms
of multi-dimensional spaces and mappings), the dynamic analysis requires an
algorithmic approach (Gilbert 1997).
In summary: the mechanisms of
aggregation can be specified in each dimension of citation analysis with reference
to potentially different dynamics. While a dogma of micro-foundation on
action has prevailed in economic and sociological analysis, aggregation in
science is expected to contain both ‘within group’ and ‘in-between group’
variations (Leydesdorff 1995). Thus, a complex dynamics is potentially
generated along each axis. Action (that is, citation) is therefore a
complex phenomenon. Furthermore, what is being aggregated can vary among
research traditions. Accordingly, the interactive and the aggregative
components of the phenomenological variations will be appreciated differently.
3.
The reception of citation analysis in Science and Technology Studies
While citations were most
fruitful for practicing scientists-allowing them to link social and textual
information-the irreflexive usage of this measurement unit in
citation analysis has generated resistance among active scientists.
Citation analysis calls for a theory of what is being analyzed; citation
analysts consequently tend to be in need of theoretical legitimation (Luukkonen
1997). Can such a theory of citation be provided by Science and
Technology Studies? What have citations and citation analysis meant for
the empirical study of the sciences during the relatively short history of
STS?
As early as 1978, Yehuda Elkana,
Joshua Lederberg, Robert K. Merton, Arnold Thackray, and Harriet Zuckerman
co-authored a first systematic reflection in what they called Towards a
Metric of Science: The Advent of Science Indicators, while earlier
contributions had been programmatic to the enterprise of developing
‘scientometrics’ as a field of study (e.g., Price 1965a and 1965b). The
1970s witnessed the gradual emergence of the industrial practice of citation
analysis (Narin 1976; Garfield 1979). Furthermore, Tibor Braun founded
the journal Scientometrics in 1978 (cf. Wouters and Leydesdorff 1995),
and soon thereafter the first academic units for citation analysis were
established (ISSRU, Budapest, 1983; CWTS, Leiden, 1984).
In terms of disciplinary
affiliations, the response to the advent of citation analysis has been more
enthusiastic among philosophers and historians of science (e.g., White et
al., 1979) than among sociologists (e.g., Edge 1979). The ‘new
sociology of scientific knowledge’ wished to focus on practices (e.g., Gilbert
1977; Gilbert and Mulkay 1984), and most of these scholars tended to avoid
formalized measurement (Chubin and Restivo 1983). During the 1980s, the
systematic application of scientometric indicators to policy issues, however,
triggered a practice of improving on the measurements (Martin and Irvine 1983;
Moed et al. 1985). As noted, other indicators like co-words were
developed (Callon et al. 1982; cf. Van Raan 1988), and citation analysis
was increasingly used in empirical STS research (e.g., Nadel 1983; Cozzens
1985).
In 1987, I organized a workshop,
followed by a theme issue of Scientometrics in 1989, in an attempt to
bridge the gap between qualitative research in STS and scientometric methods
(Leydesdorff et al. 1989). It remained a brief encounter: ever since,
the subfields of STS have increasingly specialized, as can be seen by using
aggregated journal-journal citation analysis reflexively (Leydesdorff and Van
den Besselaar 1997). On the qualitative side, scientometrics tends to be
type-cast as a rhetorical practice (e.g., Woolgar 1991; cf. Gilbert
1977). On the quantitative side, theoretical research has developed with
reference to scientometric practices (e.g., MacRoberts and MacRoberts 1987;
Luukkonen 1990; Callon et al. 1993; Leydesdorff 1995).
Nowadays, three main traditions
can be distinguished in STS: (a) socio-historical analysis mainly using
historical case study research for specifications, (b) quantitative studies oriented
towards formalization and generalization, and (c) policy and management studies
that utilize results from (a) and (b) pragmatically.53 Citation analysis
is relevant in these three traditions, but for very different reasons (Cozzens
1989; Luukkonen 1990).
4.
Evolutionary cycles
Citation analysis has been of
particular interest to science studies as an interdisciplinary field because it
has allowed analysts to move back and forth between the cognitive, the textual,
and the social dimensions of science in terms of socio-cognitive
interactions. For example, the number of times an article was cited could
be taken as an indicator of the impact of the cited author(s), and thus a translation
could be made from the cognitive use of citations in a text to the social
system of rewards operating in the scientific community. In the science
policy arena, furthermore, the citation argument has helped to make scientists
more aware of the social and communicative contexts of their arguments, and
thus to legitimate the sociological analysis of the sciences.
Both within STS and in
neighbouring disciplines, this placing of the sciences into contexts without
further theoretical and methodological reflection has been criticized.
One is not allowed to infer from the impact of an article, measurable in terms
of numbers of citations, the quality or lack of quality of a particular
researcher or research group (Collins 1985). The use of archival records
to measure social structural properties has been criticized from the side of
social network analysis (e.g., Burt 1983). Mulkay et al.
(1983) have noted the
methodological bias in inferring the other way around from citations to
cognitive impact. Discursive, social, and cognitive functions are neither
symmetrical nor synchronous. Furthermore, citation analysis can be abused
for political purposes if not sufficiently based in reflected norms of ‘best
practice’ (cf. Glänzel 1996).
STS has split into various
research traditions which tend to be highly critical of each other’s
assumptions and ‘best practices’. Yet citation, with its specifiable
relevance in all these dimensions, remains an attractive candidate for studying
the differences. Is one able to specify a hierarchy among the potentially
different functions of citations? Of course, a hierarchy can be
constructed from each of the competing perspectives. But do criteria
exist in this post-modern world to justify the choice of one selection over
another?
In this study, I have focused on
the generation of citations as carriers of cognitive information. For
this purpose, the cognitive dimension was considered as an overlay that was
first achieved historically and then codified on the basis of interactions
among scientists and their communications. It is both social and
cognitive, both a network of actors and a network of networks. Yet it is
highly selective, since the networks operate in terms of selections.
Scientific cognitions can be analyzed as the unintended (that is, latent)
eigenvalues and eigenfrequencies of the networks of these complex
interactions. Cognitions thus conceptualized remain uncertain, subject to
discussion, and in continuous flux.
Among other things, the operation
of two layers upon each other in a distributed mode enables this system to
develop ‘operational closure’ as in the case of paradigm formation (cf. Luhmann
1990; Leydesdorff 1995). During the generational phase, the cognitive
dimension can be considered as a dependent variable. In evolutionary developments,
however, the emerging dimension is able to take over control by selecting
increasingly upon the underlying ones. In the mature phase, the different
dimensions select upon each other, and the locus of control may shift
unexpectedly in terms of the densities of the selections. These
alterations in frequencies induce life-cycles: what had to be referenced at one
moment is taken for granted at the next moment, or perhaps codified as in the
case of eponymy. In a complex dynamics, selection and variation are sub-dynamics
that can only be identified by taking a theoretical position or, in other
words, by specifying a window of observation.
Each window of observation allows
for another assessment of the data under study. Once this has been
accepted among the analysts, it becomes important to specify which window one
takes, so that the partial insights thus obtained can be made reflexively clear
in terms of their relevance. In this post-modern regime, the quest for a
single theory of citation has to give way to the debate among citation analysts
who have become aware of the relativity of their positions. By being
reflexive about their positions, these authors may be able to contribute to
each others’ self-understanding and thereby reinforce quality control among
themselves. Whether the resulting interactions can be codified in a
meta-theory remains uncertain.
5.
Summary and Conclusions
I have argued that the quest for
a grand theory of citation implies a meta-theoretical question, since citation
analysis is itself based on a theoretical reflection of scientific practices
that have been shaped historically. The historical, philosophical, and/or
sociological positions taken by citation analysts, however, have usually
remained implicit. Although theoretical notions from these disciplines
have guided the research program of scientometrics as heuristics, the
analytical unravelling of citation as a complex unity into different meanings
might endanger the legitimation of citation analysis practices (Luukkonen
1997.) Theoretical discussions could easily have torn the field of
scientometrics apart-as has happened with STS in general-despite
this specialty’s firm unity based on its technological interest in exploring
the potentials of the relevant databases (Wouters and Leydesdorff 1994).
Our recent understanding of
social processes as the selective operation of distributions upon underlying
distributions provides us with ground for elaborating scientometrics in an
algorithmic mode. The various mapping techniques can then be appreciated
as providing geometrical representations. Contributions from the
qualitative side are selected as far as they allow us to specify equations and
routines that can be made relevant to the understanding of the sciences in terms
of the massive data that are becoming increasingly available.
This ‘translation’ of qualitative
insights into formalisms is well-known, for example, in econometrics. As
Langton (1989) expressed it: theories specify ‘genotypes’, while the model simulates
the ‘phenotype’ because one is able to identify the interaction terms.
Such an approach, however, requires a thorough reflection on the literature:
when are qualitative scholars analyzing ‘variation and selection’ at each
moment in time, and when is the discussion focussed on ‘change and
stabilization’ over time? These are different sub-dynamics of the complex
system, since only some (instantaneous) selections can be selected for
stabilization (over time).
How analytically distinct are the
models, and how are they confused by taking, for example, too many contextual
factors on board? When have qualitative insights been generalized?
Secondly, have attempts been made to test using independent datasets?
Citations seem an appropriate subject for discussing these issues in both
qualitative and quantitative terms: the Science Citation Index, for
example, has provided a testing ground for theories in many different
directions. Other databases are increasingly available on CD-ROM and the
Internet. However, the process of theoretical articulation must be highly
reflexive if the scientometrician wishes to understand and profit from the
qualitative side of STS.
Notes
*
I wish to thank Tibor Braun, Eugene Garfield, and Robert K. Merton for valuable
suggestions in response to previous drafts.
[1] The
French Journal des Sçavans first appeared three months before the Transactions.
Various authors still contest which nation should be accorded the honor of
giving birth to the first scientific journal, with the crucial point hanging on
the broader character of the French journal (Bazerman 1988, p. 129)
[2] In 1800,
Napoleon Bonaparte appointed a commission of jurors to combine all French civil
laws into one code. The new codification went into effect in 1804.
This ‘Code Civil’ represented a compromise between the customary law of
northern France and Roman law of the south. It also compromised both the
ideas of the French Revolution and older ideas from the south of France that
used the old Roman Law. According to the Cambridge Modern History (1958),
‘the Codes preserve the essential conquests of the revolutionary
spirit─civil equality, religious toleration, the emancipation of land,
pulbic trial, the jury of judgement. (...) In a clear and compact shape,
they presented to Europe the main rules which should govern a civilised
society.’ (See http://www.fast-times.com/political/dictN20.html; http://www.cp.duluth.mn.us/~tmcs/CODENAP0.htm)
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