Table 1.1. The four main types of transfer (source: Molas-Gallart 1997)
| Mode | No adaptation | Adaptation |
| Actors | ||
| Transfer internal to a single unit | Internal straight transfer | Internal adaptational transfer |
| Transfer between two or more units | External straight transfer | External adaptational transfer |
However, from a methodological perspective, this does not solve the question of recognizing technologies that can be the object of a dual transfer. Several identification methods are thus considered in various research works.
The most commonly used method employs case studies. In defense economics, the interest of this method is in bypassing the reliability problems of available data on technologies. Many case studies have been conducted on various sectors or on various technologies, such as machine-tools, civilian aeronautics, information technologies with semiconductors, data processing and the Internet, to name just a few (Mowery 2010); for a full summary see the prospective strategy study conducted by IRIS1. These case studies show the diversity of situations and the dual transfer methods, but do not offer an overall view on the subject.
A further solution enabling the identification of a technology passing from the military sector to the civilian sector involves the study of the financing source and can be an identification solution. Indeed, it is at least possible to formulate the hypothesis that the research programs of a defense ministry a priori assign a military nature to innovations that could result from the program. It marks these technologies as military or at least dual. It is on this principle that certain analyses rely for the study of technology transfers from the public R&D to market sectors, and for stressing the influence of the military nature of the innovations on these transfers (Chakrabarti et al. 1993; Chakrabarti and Anyanwu 1993). It is however difficult to maintain a clear distinction: what falls within the defense budgetary perimeter varies from one country to another, depending on its history, on the size of its Defense Industrial and Technological Base (DITB), on its defense strategy choices, etc.
The actors can also play the role of technology markers. One technology developed by actors of the DITB would be qualified as defense technology, unlike others. This is, among others, one of the approaches chosen by Chinworth (2000a) to analyze duality in Japan. This method makes it possible to approach the question from a global perspective, but involves the risk of considering, in the analysis, technologies developed by manufacturers that are partly active in the civilian field, and hence not necessarily intended for defense purposes.
Finally, the most clear-cut approach is to consider that certain technologies are intrinsically associated with defense activity. This is, for example, the approach of Acosta et al. (2013, 2017), which assume that certain technological classes of the International Patent Classification (IPC) are by hypothesis technological classes in the defense field. Hence, studying the sectors of application of these technologies, which extend beyond the defense perimeter, these authors measure their level of duality. Methods can complement each other and thus contribute to refining the identification of technologies that are relevant for study (Chinworth 2000b).
The analysis of technologies, and notably that of the knowledge composing them, is an interesting approach. Indeed, beyond the technological object itself, technology can be defined through the set of knowledge it encompasses (Carlsson and Stankiewicz 1991). Duality is then related to knowledge dissemination between civilian and defense sectors. This reinforces the idea that it is difficult to a priori determine if a technology is dual or not (Mérindol 2005). Defense programs are knowledge-intensive projects, with varied sources and unpredictable final results. Consequently, knowledge duality may cause know-how transformation and generate opportunities, both for civilian manufacturers and for those active in the defense sector (Guillou et al. 2009).
From this perspective, the existence of either civilian or military prevalence in the duality process is more difficult to interpret than in the spin-off paradigm, as defined by Alic et al. (1992). In order to benefit from duality, “the whole challenge resides […] in the equilibrium between specialization and building a joint knowledge base by the actors” (Mérindol 2005, p. 52).
This analysis in terms of knowledge leads to two opposite conceptions:
– the first would be to consider knowledge duality as a spillover, strictly speaking (a term that is more relevant than spin-off and spin-in in knowledge economics). Then duality would be the result of spillovers (knowledge transfers) between civilian and military fields, without premeditation on behalf of any of them. Duality is then perceived as a process of translation from one field of application to another. This view is finally quite close to that proposed by Chinworth (2000a) and Acosta et al. (2013, 2017);
– the second involves the simple consideration of the presence of spillovers as a corollary of the absence of duality:Particular research is done exclusively in one domain and adapted more or less without change in others. The existence of spillovers, therefore, is not evidence of duality, and might in fact be evidence of its absence. Thus, promotion of spillovers can be viewed as a policy designed to correct the ‘duality’ failure of a program of R&D. (Cowan and Foray 1995, p. 852)
According to this perspective, duality resides in the joint civilian–military design of knowledge. In this case, duality is an input data of technological change; it involves an evolution, if not identical, at least compatible with the technical characteristics of civilian and military applications.
This being said, a certain number of works have been conducted which indicate that the border between the two sectors is highly porous to knowledge. Three key stages in the research enable the progress toward a method for systematic knowledge analysis in duality. The first stage is that of studies conducted at the company level, according to which the sources of knowledge employed by defense companies are both defense and civilian companies (Chakrabarti et al. 1993). The second is that of studies at the technology level, which try to track all the links between knowledge produced in the defense field and that produced in the military field (Acosta et al. 2011, 2013, 2017). They pay particular attention to spillovers, as is the case for Japan, in the work of Chinworth (2000a). Finally, one article proposes to lay the bases for a systematic study of knowledge by means of patents. This study does not rely on a view of knowledge duality in terms of spillovers, but in terms of similarity in knowledge production, otherwise put, a cognitive proximity between the civilian field and the defense field. In that respect, it is in agreement with case studies that try to identify similarities and differences between civilian research and defense research in various technological domains (Lapierre 2001). Hence, this analysis is close to the above-mentioned second perspective, according to which, instead of being characterized by transfers, duality is characterized by a potential joint production of knowledge and it advances a shared foundation used by both parts (Meunier and Zyla 2016).
In addition to knowledge composing defense technologies, the complexity of these systems contributes to obscuring the link between civilian innovation and defense innovation. During World War II and in the decades after it, arms programs grew in complexity. The hydrogen bomb, fighter jets and ballistic missiles are examples that prove this dynamics. In order to develop these complex technologies, those who designed these programs