Sophie Hooge

& Le Masson

What does the proof-of-concept (POC) really prove? A historical perspective and a cross-domain analytical study

Keywords: POC, TRL, conception, validation, exploration

En dépit du fait que la preuve de concept ou POC soit devenue une pratique courante des organisations dans les processus de prise de décision et de coordination internes et externes, la littérature en management stratégique s'est jusqu'à présent peu emparée du sujet. Dans ce papier, nous nous sommes intéressés aux questions suivantes : D'où vient la notion de POC et comment a-t-elle évoluée au fil du temps ? En quoi le POC constitue une catégorie particulière de preuve ? Pour répondre à ces questions, nous avons d'abord réalisé une étude historique de la genèse du concept, à savoir dans l'écosystème aérospatial et aéronautique américain. Puis, nous avons mené une étude analytique du transfert de la notion dans les écosystèmes du biomédical, de la recherche publique, du développement de nouveaux produits / de l'innovation / de l'entreprenariat et enfin des technologies de l'information. Ce papier a permis de montrer que le terme, qui est né dans les années 1960, a progressivement rencontré un succès dans les contextes où il a fallu faire entrer de nouveaux acteurs dans la chaîne de valeur de la conception qui était jusqu'alors très intégrée, et ce souvent par l'amont. En ce sens, le POC, en tant preuve de validation et d'exploration, semble être un outil particulièrement utile aux « acheteurs » et aux « vendeurs » dans des processus avec une dimension exploratoire.

INTRODUCTION

The proof-of-concept or POC which is presented as a 'critical step' in the innovation process (Bendavid and Cassivi, 2016) is widely used by companies and their ecosystem. Christophe Reinert, Head of Open Innovation at EDF Groupglobal leader in low-carbon energy -, does not hesitate to describe the POC as "a step towards innovation and value creation, a learning step that is often decisive if it is well managed" (Comité Richelieu and Le médiateur des entreprises, 2019). However, the POC remains until now abandoned by strategic management research. It may be because the POC is consider either as a solely technical milestone (Eesle et al., 2014) or a buzz word among others in communities of innovative practitioners and what is more an ill-designed notion.

The objective of this paper is to restore the POC by showing that it designates an important strategic and critical moment in value chain evolutions. We will see that the POC concept has survived since its creation in the 1960s and amplified over the last decades to address specific challenges of the innovation process. Thus, the POC appears to be a key concept for organizing strategic exchange in design. On the one hand, one must prove that one part is true, and on the other hand, one must show that there are still design activities to be carried out.

In this paper, we seek to investigate two research questions: (1) Where does the concept of 'proof-of-concept' come from and how has it evolved over time? (2) How does 'proof-ofconcept' relate to a peculiar category of proof? To address these research questions, we will use two approaches. The first approach is about conducting a historical perspective to trace back the genesis of the POC concept. The concern is to begin to identify the contexts of use of 'proofof-concept' in industrial ecosystem and the nature of the associated proof. The second approach is about conducting a cross-domain analytical study to explore the appropriation of the proofof-concept by a wide range of actors and sectors. The aim of such a study is to extract from the plural practices of POC a core of common characteristics and a halo of domain-specific specificities. We believe that this common core could be described by the concomitance or even the original articulation between proof and demonstration of residual unknown to explore. Online, 3-5 juin 2020

The paper is articulated as follows. In the next section, we will start by recalling the research questions and presenting the research hypothesis before providing an in-depth description of the research approach. We will perform the historical perspective and then the cross-domain analytical study in devoted sections. Then, we could built on these results to discuss the contribution of POC concept for strategic management.

RESEARCH HYPOTHESES AND METHODOLOGY

RESEARCH HYPOTHESES

To understand POC concept's emergence and diversity of meaning, our first hypothesis is that the term was coined by NASA in 1970s in relation to the Technology Readiness Levels (TRLs) and spread over a variety of disciplines such as biomedical and computer sciences. Secondly, despite the existence of plural definitions, we assume that POC handles an original type of proof -a 'double proof'that bears both known and unknown dimensions of demonstration.

RESEARCH DESIGN

The following research was carried out in two large sequences. The first step was to identify and describe the origins of the term 'proof-of-concept' to reconstruct its genesis. Particular attention was given to tracing the context and environment associated with the first occurrences of this term to finely account for the properties that this type of proof bears. The second step was to analyze the diffusion of 'proof-of-concept' through four or five 'transfers'. A transfer is defined as an appropriation of 'proof-of-concept' by another ecosystem or discipline than the aerospace and aeronautic ecosystem where the notion was born.

DATA COLLECTION AND ANALYSIS

To undertake the first part of the study, which is based on a historical perspective, two major methods were used. The first method was to start from the myth concerning POC coming from NASA TRLsthe analysis will show that the cradle of emergence was older. In an operational manner, we started by looking at scientific articles that were written by NASA's collaborators, especially to understand the elements that motivated its emergence. Afterwards we tried to get to the root by investigating reports from NASA and the U.S. government, and affiliating them to major events in U.S. and international aerospace history. We also looked at more recent Online, 3-5 juin 2020 reports and scientific articles for a complete timeline. To facilitate understanding and reading of the historical perspective, it was broken down in five major phases. A summarized illustration closes this historical perspective. The second method used was to cross-reference this first genealogical study to confirm it and possibly complete it by investigating the first occurrences of 'proof-of-concept' that can be found in academic literature. In an operational manner, we made a query on JSTOR database using the keywords "proof-of-concept" OR "proof of concept", choosing a publication period prior to 1980 (this date was chosen in view of the historical perspective), with documents in all languages and on the basis of all content. This search yielded twenty-five results. Six results were removed because they were not journal articles (5) or the source that was not accessible (1) prevented us to perform our analysis. Our aim was not to provide a complete and thorough analysis of this literature. We focused our attention on the authors of these articles, especially on behalf of: i) which organization they wrote which is almost always mentioned in the article and ii) their positions in this organization at that time which is almost never mentioned in the article, but knowable through archives on the internet.

To undertake the second part of the study, which is based on a cross-domain analytical study, we investigate 'transfers' in four ecosystems: (1) biomedical, (2) public research, (3) NPD, innovation and entrepreneurship, and (4) information technology. Two principles guided the choice of these ecosystems. The first principle was to study ecosystems that concentrate contemporary POC practices. We validate the first point by a detailed analysis of the ecosystems that could be linked to the first sixty results of a Google query made on 21 April 2020 with the following keywords "proof of concept" OR "proof-of-concept". The second principle was to build a sample of transfers with enough material for defining qualitatively to identify redundant and differentiating properties. We sought to understand what motivates the introduction of the proof-of-concept by trying as much as possible to associate these transfers with trends that have marked the history of the domain and therefore also provide rough temporal landmarks. All in all, it allows us to build conjecture on adoption or specific meanings associated to transfer, and propose a cross-domain analytical study that enlighten the function and context of use of the proof for each ecosystem. We adopt a presentation of the transfers that provide a harmonious unfolding of meaning diversity moreover than transfers' temporality. Online, 3-5 juin 2020

GENESIS OF 'PROOF-OF-CONCEPT' IN U.S. AEROSPACE AND AERONAUTIC ECOSYSTEM: AN HISTORICAL PERSPECTIVE

In this section, we trace the history of the 'proof-of-concept' in the U.S. aerospace and aeronautic ecosystem where this concept was born. In order to better understand the issues and problems that motivated the creation and deployment of the proof-of-concept, particularly through the Phased Review Process (PRP) and the Technology Readiness (TRL) scale, we review some major dates in American and world spatial history. This section also allows us to make a list of the characteristics of this type of proof with chronological markets. These properties will be taken advantage of in the cross-domain analysis study.

In the first part of this section we focus on the geopolitical context which prompted the creation of NASA. In a second part we trace back the first occurrence of 'proof-of-concept' in relation to the Phased Review Process. In a third part we investigate the dynamics of emergence of the TRL scale then we cross this historical perspective with the analysis of the first academic publications which mobilized this notion before the end of the 1980s. In a fourth part we describe the deployment and integration of the TRL scale in NASA's ecosystem. Finally, in a fifth part we stress modern uses of TRLs in NASA's and worldwide aerospace and defense sector.

1940S-1950S: COLD WAR, SPACE RACE, AND NASA'S FOUNDATION

After World War II began a period of geopolitical battle, known as the Cold War, between the United States (U.S.) and the Soviet Union and their respective allies. In this context, space became a great competitive arena between the two major powers. Through the Space Race each of them sought to show the world its technological superiority and in fine its model superiority.

In this competition the Soviet Union achieved a major milestone that was not palatable to most Americans in the fall of 1957 : they launched the first man-made objects into Earth orbit -Sputnik 1 and Sputnik 2, the first spacecraft which carried out a living animal.

Although the U.S. finally succeed to launch their own satellite Explorer 1 in February 1958 which had been developed by the Army Ballistic Missile Agency, the U.S. Congress remained worried about national security and technological leadership. Therefore, in a message to the Congress in April 1958, President Eisenhower proposed the establishment of a National Aeronautics and Space Agency (NASA) as an independent agency of the U.S. Federal Government that would absorb staff, laboratories and aerospace research activities of the Online, 3-5 juin 2020 present National Advisory Committee for Aeronautics (NACA). The creation of NASA was acted in July 1958. NASA was created to be responsible for civilian or 'peaceful' space science and aeronautical research in its own facilities or by contract and would also perform military research if required by the military departments [START_REF] Emme | Aeronautics and astronautics: An American chronology of science and technology in the exploration of space, 1915-1960[END_REF].

1960S: PHASED REVIEW PROCESS AND PROOF-OF-CONCEPT

Another huge milestone in this Space Race performed by the Soviet Union touched the U.S. in their pride and leadership and pushed them to react. Indeed, in April 1961, the Soviet cosmonaut and pilot Yuri Gagarin was the first human to journey into outer space when his Vostok spacecraft while he completed an orbit of the Earth. This event triggered the launch of the Apollo Program in May 1961 by President Kennedy. The goal was simple and clearputting a man on the moon and returning him safely before the decade was out.

To achieve such a challenge and more generally meet the national space policy, NASA developed in the 1960s the Phased Project Planning, commonly referred as the Phased Review Process [START_REF] Cooper | Third-generation new product processes[END_REF]. According to [START_REF] Cooper | Third-generation new product processes[END_REF], the purpose of the Phased Review Process was to take apart the development process into discrete phases. This process breakdown by phases not only provided a better framework for funding and drawing up contracts, but also aimed at reducing technological risks. Indeed, this measurement and control was a safeguard for NASA that all the requirement had been met, especially that the engineering tasks had been completed by its teams or its contractors and suppliers before moving on to the next phase. As evidenced by more recent NASA's resources such as the report of David D. Few from the NASA's Ames Research Center (Few, 1987), Phase II was to be named 'proof-of-concept' or 'POC'. This assumption is historically confirmed by a 1966's report which "summarizes and reports the results of the Phase II (proof-of-concept) program for the development of an Advanced Meteorological Sounding System." [START_REF] Griggs | An advanced meteorological system, phase II (proof-ofconcept)[END_REF]. Information about this report was published on the website of the Defense Technical Information Center (DTCI). DTCI is the repository for research and engineering information for the U.S. Department of Defense (DoD) and its ecosystem who also adopted the Phased Review Process as project management methodology [START_REF] Cooper | Third-generation new product processes[END_REF].

Although this methodology has been criticized by some executives, it probably helped to meet President Kennedy's challenge. Indeed, in July 1969 the mission Apollo 11 allowed two of the Online, 3-5 juin 2020 three crew astronauts (Neil Armstrong and Buzz Aldrin) to set a foot on the moon and safely come back home.

1970S: EMERGENCE OF THE READINESS LEVELS AT NASA

In September 1969, a few months after this exploit, a report of the Space Task Group entitled 'The Post-Apollo Space Program: Directions for the Future' was published. In this one, the Task Group took stock of the Apollo Program and made recommendations for future space activities (Space Task Group, 1969). It recognized that Apollo Program stimulated the creation of subsequent technological capability. It is about "the growth of a valuable reservoir of highly trained, competent engineers, managers, skilled workmen and scientist within the government, industry and universities" with the support of "facilities, technology and organizational entities capable of complex management tasks". One of the characteristics of the balanced program for the future envisioned by the Task Group in the same report is 'opportunity'. Indeed, it is stated as a goal that "[a]bundant opportunities exist for further exploitation of this capability. A balanced program will permit adequate attention to applications and science while also creating new opportunities through development of new capability". This is how the Supporting Research Technology (SRT) Program and their mission planners became in charge of adding value to the technological capability developed during the 1960's Apollo Program through their integration into future missions. According to [START_REF] Sadin | The NASA technology push towards future space mission systems[END_REF], the duty of mission managers was to use "program funds to adapt and requalify the "shelf-stored" technology inventory". On the other side, the Advanced Research Technology (ART) Program and their researchers were responsible for pursuing new concepts (ibid.). This approach called 'technology push' or 'opportunity driven' completed the dominant model of 'program pull' or 'need driven' commonly used at NASA where a specific technology was only developed in response to a need previously formulated by the mission planners [START_REF] Héder | From NASA to EU: The evolution of the TRL scale in Public Sector Innovation[END_REF][START_REF] Sadin | The NASA technology push towards future space mission systems[END_REF]. Such a paradigm shift was successful in some cases but also often raised issues in the 1970s [START_REF] Sadin | The NASA technology push towards future space mission systems[END_REF][START_REF] Straub | In search of technology readiness level[END_REF]. According to [START_REF] Sadin | The NASA technology push towards future space mission systems[END_REF], "the differing perceptions of the researchers and the mission planners between the intended and actual proof of readiness was often the cause of an aborted handoff, or technology transfer, of ART [Advanced Supporting Research Technology] to the SRT [Supporting Research Technology] users". They also explained that the definition of the following categories: 'basic research', 'feasibility', 'development' and 'demonstration' "have caused ambiguous understandings between, the Online, 3-5 juin 2020 researchers, their management, and the potential program users". NASA's first challenge was to enhance the understanding of the researchers and the mission planners about the 'technology readiness' in order to perform the technology transfer at the good point.

This new paradigm also raised another issue regarding the 'flight readiness' because new concepts and technologies could be developed regardless a space mission. Indeed, a framework was needed to assess "how proven a certain technology was" in a context where "they cannot necessarily prove their feasibility in an actual space mission at the time of development" [START_REF] Héder | From NASA to EU: The evolution of the TRL scale in Public Sector Innovation[END_REF]). NASA's second challenge was to evaluate the 'technology readiness' on a regularly basis during its development process.

To respond to these two challenges the NASA Office of Aeronautics and Space Technology (OAST) laid the foundation of the concept of 'readiness levels' in 1974 [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF][START_REF] Straub | In search of technology readiness level[END_REF] that were later codified in a paper [START_REF] Sadin | The NASA technology push towards future space mission systems[END_REF]. The terminology 'proofof-concept' is used to describe the third level named "Proof-of-concept demonstrated, analytically and/or experimentally" (ibid.). More generally, readiness levels are claimed to "provide the Agency [NASA], and the communities with which it interact a more precise means of describing the depth to which a research and technology program is to be pursued" [START_REF] Sadin | The NASA technology push towards future space mission systems[END_REF]. In that sense, the formalization of readiness levels echoes "the creation and management of boundary objects" which is presented by Star and Griesemer (1989) as "a key process in developing and maintaining coherence across intersecting social worlds". They are "objects [that may be abstract or concrete] which are plastic enough to adapt to local needs and the constraints of the several parties employing them, yet robust enough to maintain a common identity across sites" (ibid.). To that extent, TRL 3 or 'proof-of-concept' may be characterized as a 'boundary object'.

Let us continue by crossing the beginning of this historical perspective with the analysis of academic literature prior to 1980. The institution and position of the authors of the seventeen journal articles, their related use of POC concept (quote), and references are presented in Table 1. We have not yet succeeded in finding the positions for all the authors, we thus used the expression 'to be defined (TBD)' in Table 1 to characterize these holes.

Looking for POC roots, we also found two isolated articles in philosophy without correlated interpretation but, it remains important to specify that one of them constitutes the first academic article found which use the notion as early as 1963 [START_REF] Rotenstreich | On constructing a philosophical system[END_REF]. This first article is Online, 3-5 juin 2020 about the construction of a philosophical system. The author uses POC term to underline the ability to manage the unity of knowledge acquisition through concepts assumption (teleological proof of knowledge unity). The second article [START_REF] Bunge | The physicist and philosophy[END_REF] is about the benefits of the interplay between physicists and philosophers. POC is used to designate a step of abstraction within the reasoning in physics (technique of proof of concept independence).

With the exception of these two references in philosophy, the collected information is consistent with our above declaration. Indeed, most of the authors who embrace the terminology have technical management or engineering positions in the U.S. aerospace and aeronautic ecosystem (cf. Table 1). They worked either at NASA, or in a company or university which most likely had a contract with NASA. Moreover, sometimes articles were written in collaboration between the two institutions, as it can be seen in the last section of the table. Research on vertical and/or short take-off and landing (V/STOL) aircraft, which are aircrafts that do not require or limited runways without being helicopters, has largely catch the attention of these papers. To a lesser extent, another stream of literature, that can be extracted from the sample, is related to the National Science Foundation (NSF) and its contracts to translate research efforts into general public-use applications. "During some 3 months of orbital operations, Seasat collected a unique set of global synoptic data on ocean winds, waves, temperature, and topography. all indications from a preliminary analysis of these data are that most of the mission's proof-of-concept objective -the demonstration of nearly allwheather microwave surveillance of the world's oceans -will be met ..." Online, 3-5 juin 2020

Secretary , 1988). We learned that among Presidential Directive's goals and objectives, the revised national policy encouraged more coordination and collaboration inside the civil sector (i.e., between NASA and other governmental agencies, companies and universities), between sectors (civil, national security, commercial), and with international (allies) partners. To continue in this direction President George H. W. Bush announced the Space Exploration Initiative on the 20th anniversary of the Apollo 11 Moon landing. According to [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF], this space public policy continued and expanded the use of 'readiness levels' that was enriched with an eight and a ninth level and probably had already taken the shape of a scale before the formalization of Technology Readiness Levels (TRLs) scale by Mankins in a white paper in 1995. Such a tool appeared to be even more useful "due to the need to communicate technology readiness status and forecasts between the technology research community and the exploration mission planning community" [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF]. This newly expanded TRL scale was also employed in the Integrated Technology Plan for the Civil Space Program in 1991 [START_REF] Oast | Integrated Technology Plan for the Civil Space Program[END_REF]. Indeed, in 1995 Mankins formalized the TRL scale as "a systematic metric/measurement system that support assessments of the maturity of a particular technology and the consistent comparison between different types of technology" [START_REF] Mankins | Technology Readiness Levels: A White Paper, Advanced Concepts Office[END_REF]. In this white paper the TRL 3 is reformulated as follows in the new 9-level scale: "Analytical and experimental critical function and/or characteristic proof-of-concept". The paper also provided a short description of each level with an example and its attainment criteria. For the TRL 3, we can read:

At this step in the maturation process, active research and development (R&D) is initiated. This must include both analytical studies to set the technology into an appropriate context and laboratory-based studies to physically validate that the analytical predictions are correct. These studies and experiments should constitute "proof-of-concept" validation of the applications/concepts formulated at TRL 2. For example, a concept for High Energy Density Matter (HEDM) propulsion might depend on slush or super-cooled hydrogen as a propellant: TRL 3 might be attained when the concept-enabling phase/temperature/pressure for the fluid was achieved in a laboratory.

Cost to Achieve: Low 'Unique' Cost (technology specific) [START_REF] Mankins | Technology Readiness Levels: A White Paper, Advanced Concepts Office[END_REF].

In a later paper, [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF] enriched the definition he provided few years earlier. For our research question, a modification and clarifications can be emphasized. The paper clarified the point that a class of inventions may be "proven" analytically whereas another class of inventions "require physical experimental validationsuch as those involving highly complicated 12 Online, 3-5 juin 2020 concepts or those involving environmentally dependent phenomena or novel material effects" [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF]. Moreover, the costs to achieve that were previously presented as low and unique are therefore presented as "low to moderate" because "the costs can vary significantly from one area of research and development to another". The article also stated that "[b]ecause of the relatively high risk and long lead times, it is less likely that funding at TRL 3 or below would be available from most types of venture funding sources" [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF].

2000S-2010S: MODERN USES OF TRLS IN NASA'S ECOSYSTEM AND WORLDWIDE AEROSPACE & AERONAUTIC ECOSYSTEM

In their paper, [START_REF] Straub | In search of technology readiness level[END_REF] provided a review of NASA's uses of TRLs depicted in their public documentation. Table 2 provides a chronological summarized analysis of these uses. Framework used during the Technology Readiness Assessment (TRA) to systematically determine a system's technological maturity in terms of TRLs and the difficulty to move to the next TRL.

XXIXe Conférence Internationale de Management

Stratégique 13 Online, 3-5 juin 2020

In 1999, the Armed Services Committee of the U.S. Senate asked the Government Accounting Office (GAO) to investigate the situation of the Department of Defense (DoD). Such an investigation was carried out because the DoD planned to increase funding for new development programs while previous "programs very often suffered significant delays and vast cost increases" [START_REF] Héder | From NASA to EU: The evolution of the TRL scale in Public Sector Innovation[END_REF]. In its report, GAO applied the framework of the TRL scale to assess various programs to better understand why some of them well or poorly performed.

They found that DoD integrated technologies anywhere from TRL 2 to TRL 9 and programs that integrated TRL 6-technologies no longer experienced any additional cost. The main message of this report was therefore that by formalizing the maturity of technologies on the TRL scale and by refusing to support technologies that are too immature (below TRL 7 in any circumstances, with the preferred TRL 8 TLR 9), DoD will improve the performance of these acquisition programs (GAO, 1999;Jean, 2018). The DoD adopted the TRL scale in 2000.

Other U.S. governmental agencies "beyond NASA adopted a NASA-derived or NASA-like TRL system" [START_REF] Straub | In search of technology readiness level[END_REF]. Indeed, on the one hand, some of U.S. governmental agencies such as the Department of Defense (DoD) or the Department of Homeland Security (DHS) closely adopted the TRL with minor wording modifications, and on the other hand, others such as the Department of Energy (DoE) applied major modifications to the 9-level scale.

In the 2000s, the TRL also crossed the border of the U.S. and inspired international space agencies and their contractors such as the European Space Agency (ESA) that adopted the TRL scale in the mid-2000s. In a handbook published in 2008, ESA declared that "the purpose of timely and accurate technology readiness assessments is to inform management and support decisions as part of the implementation of advanced technology system development projects"

and "[t]he Technology Readiness Levels have been defined to provide a common metric by means". In this handbook, ESA took the NASA's thermometer diagram without change and closely followed the technological levels while definitions provided in Mankins' white paper (1995) were enriched. Moreover, the handbook had an appendix section with "guidelines for the definition of the software technology readiness levels". In 2013, the TRLs were canonised through the ISO standard 16290 'Space systems -Definition of the Technology Readiness Levels (TRLs) and their criteria assessment' which is highly inspired by NASA and DoD. ISO 14 Online, 3-5 juin 2020 Since the beginning of the 21st century, TRLs has globally gained popularity in numerous organizations [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF] not only in aeronautical and defense sector but more generally in high-tech industry such as automobile, spreading POC concept as TRL 3.

HISTORICAL PERSPECTIVE OVERVIEW

In Figure 1, we provide an overview of this historical perspective that described the genesis of 'proof-of-concept' in the U.S. aerospace and aeronautic ecosystem.

TRANSFERS OF 'PROOF-OF-CONCEPT' IN OTHER ECOSYSTEMS: A CROSS-DOMAIN ANALYTICAL STUDY

In this section, we will show that 'proof of concept' appropriation in various ecosystems greatly contributed to its broad expansion. The term which appeared in the 1960s has since TRL scale stabilization in the 1990's become widely democratized, as the Google NGRAM graph in

BIOMEDICAL TECHNOLOGY: DEVELOPMENT AND DISCOVERY/DESIGN

The sector of POC transfer that adopt the concept with the closest philosophy is biomedical technology. It is well known fact that bringing a new drug to the market is a business of high risk. Indeed, it generally costs about $2.5 billion and lasts more than twelve years [START_REF] Avorn | The $2.6 billion pill-methodologic and policy considerations[END_REF] while the attrition rate along the life cycle is tremendous [START_REF] Waring | An analysis of the attrition of drug candidates from four major pharmaceutical companies[END_REF]. Moreover, following the tradition of modern medicine as an evidence-based practice and responding to the excesses that have marked our history, the pharmaceutical and biomedical industry sectors are today characterized by one of the most regulated environments related to safety and ethics [START_REF] Jekunen | Decision-making in product portfolios of pharmaceutical research and development-managing streams of innovation in highly regulated markets[END_REF].

Biomedical Technology Development

The development process of new pharmaceuticals has been broken into phases for many years.

The same mechanism was later employed in the 1960s by NASA through its Phased Review Process. It was probably around the 1980s that the transfer of the 'proof-of-concept' occurred through its insertion in existing stage phases for which regulatory authorities (FDA, ANSM, Health Canada, …) are guarantors. At that time, such stages became convenient indicators in corporate dashboards for investors who were not necessarily specialized in the biomedical field. Indeed, in a contemporary way, the second phase of these clinical trials (Phase IIa) is generally presented as 'proof of concept' studies [START_REF] Cartwright | Proof of concept: a PhRMA position paper with recommendations for best practice[END_REF][START_REF] Corr | The pathway from idea to regulatory approval: examples for drug development[END_REF]Preskorn, 2014, Yuan et al., 2015). During this stage, "the study drug is tested for the first time for its efficacy in patients with the disease or the condition targeted by the medication" (Corr and Online, 3-5 juin 2020 Williams, 2009), i.e., experimental studies are performed into an appropriate context because the concept involve an environment-dependent phenomena -to be in line with the description of TRL 3 by [START_REF] Mankins | Technology readiness assessments: A retrospective[END_REF]. Furthermore, according to the Pharmaceutical Research and Manufactures of America (PhRMA), "[t]he POC demonstrates that the drug did what it was intended to do, that is, interacted correctly with its molecular target and, in turn, altered the disease" [START_REF] Corr | The pathway from idea to regulatory approval: examples for drug development[END_REF]. Contrary to later stages of clinical trials, 'proof of concept' studies "typically involv[es] a small number of subjects and more latitude in statistical requirements" (Preskorn, 2014). Such 'proof of concept' or 'POC' studies must "provide evidence that a molecule is likely to be successful in later stages of drug development process (i.e., late phase II and large-scale phase III studies required for U.S. Food and Drug Administration [FDA] approval)" (Preskorn, 2014). In the same way, PhRMA presented the POC as "the earliest point in the drug development process at which the weight of evidence suggests that it is 'reasonably likely' that the key attributes for success are present and the key causes of failure are absent" and "perhaps the key deliverable of exploratory drug development" [START_REF] Cartwright | Proof of concept: a PhRMA position paper with recommendations for best practice[END_REF]. In addition of being a milestone in an internal development process to "allow drug developers to make 'Go/No Go' decisions about proceeding with larger, more expensive studies" (Preskorn, 2014), such studies are a an 'obligatory passage point' [START_REF] Callon | Some elements of a sociology of translation: domestication of the scallops and the fishermen of St Brieuc Bay[END_REF] that must sufficiently convince the competent authorities to obtain their agreement to pursue larger clinical trials.

Biomedical Technology Discovery/Design

In the same vein of Cooper's stage-gate process (1994) that aim to 'capture the entire process from idea through to launch, and not just the middle stage, Development", 'proof-of-concept' terminology shifted to upstream process steps to describe "up-front homework or predevelopment work" [START_REF] Cooper | Third-generation new product processes[END_REF]. Indeed, 'proof-of-concept' is used to describe discovery (or design, see [START_REF] Elmquist | Towards a new logic for Front End Management: from drug discovery to drug design in pharmaceutical R&D[END_REF] phase studies [START_REF] Evans | Anne Evans: assessment of a biotechnology market opportunity[END_REF] or preclinical tests/studies [START_REF] Detela | EU regulatory pathways for ATMPs: standard, accelerated and adaptive pathways to marketing authorisation[END_REF][START_REF] Fink | FDA regulation of stem cell-based products[END_REF] by leveraging in vitro or in vivo models of disease [START_REF] Detela | EU regulatory pathways for ATMPs: standard, accelerated and adaptive pathways to marketing authorisation[END_REF]. This transfer probably occurred in the 1990s with the massive arrival of new technologies (e.g., high-throughput screening) to address drug discovery [START_REF] Drews | Drug discovery: a historical perspective[END_REF]. Drug discovery was then increasingly driven by external biotechnology experts in universities or biotechnology companies rather than chemistry experts of large pharmaceutical companies [START_REF] Corr | The pathway from idea to regulatory approval: examples for drug development[END_REF]. Indeed, it appears that the POC XXIXe Conférence Internationale de Management Stratégique 17 Online, 3-5 juin 2020 was needed to organize the externalization of the upstream process. This more upstream interpretation is largely found through academic literature in biological and biomedical sciences (for instance see [START_REF] Stone | A hexavalent Coxsackievirus B vaccine is highly immunogenic and has a strong protective capacity in mice and nonhuman primates[END_REF]. This interpretation is also depicted for pharmaceuticals in the Biomedical Technology Readiness Levels provided in appendix of the Technology Readiness Assessment (TRA) Deskbook of the DoD (Office of the Director Defense Research and Engineering, 2009). Indeed, we can read that TRL 3 decision criterion is about "[i]nitial proof-of-concept for candidate [drugs or biologics/vaccines] constructs is demonstrated in a limited number of in vitro and in vivo research models". For medical devices, "in vivo and in vivo research models" is replaced by "laboratory model (may include animal studies)" whereas for medical Information Management/Information Technology (IM/IT) and medical informatics, decision criterion is expressed as follows: "Medical informatics data and knowledge representation schema are modeled".

The concomitance of these two interpretations of POC in the world of new biomedical technologies (e.g., in a single research article, see [START_REF] Detela | EU regulatory pathways for ATMPs: standard, accelerated and adaptive pathways to marketing authorisation[END_REF]) causes confusion when it comes to technology transfer between laboratories or research organizations to pharmaceutical or medical device companies. In fact, the former type of stakeholders often speaks of POC to describe the fact that they had successfully conducted pre-clinical trials while this language refers to clinical trials for the latter type of stakeholder. This ambiguity in practices was revealed to us by a Technology Transfer Project Manager at SATT Lutech, a French structure that accompanies innovative projects from academic laboratories to the market. Indeed, he said that "the researcher may consider having established his POC by validating the mechanism of action on a few human cells while the industrialist thought that the drug had already been tested on several dozen sick patients" (interview date: 4 February 2019).

PUBLIC RESEARCH: TECHNOLOGY TRANSFER AND FUNDING

Proof of concept' is not only used by researchers in biological or biomedical sciences, but also more generally in public research ecosystem independently of the discipline. Two main uses of 'proof of concept' can be described. Online,345The first use, i.e., technology transfer [START_REF] Feller | Universities as engines of R&D-based economic growth: They think they can[END_REF], draws inspiration from the assessment of technology maturity to ensure that the transfer between researchers (ART) to the mission planners (SRT) took place at the good point [START_REF] Sadin | The NASA technology push towards future space mission systems[END_REF]. For instance, Jensen and Thursby (2001) used the terminology of 'proof of concept' to describe a stage of development for university inventions when they were licensed. In the same line, [START_REF] Markman | Entrepreneurship and university-based technology transfer[END_REF] found that licensing strategy of university-based technology is "strongly influenced by the stage of the technology, which they classify into four overlapping categories including early-stage inventions, proof of concept, reduction to practice, and prototyping". For 'proof of concept' stage described as follows: "[a]n idea or new technology has been developed to the point that it shows signs of having the proposed effect", licensing for sponsored research is preferred while "market applications are still unclear" [START_REF] Markman | Entrepreneurship and university-based technology transfer[END_REF]. [START_REF] Clarysse | Academic spin-offs, formal technology transfer and capital raising[END_REF] who studied the creation of academic spin-offs said "[t]he stage of NPD of the spin-off at start-up was defined on a scale where: 1 = idea phase; 2 = proof of concept, i.e. α prototype; 3 = prototype that works in a real-life environment, i.e. β prototype; 4 = concrete market-ready product".

Technology transfer

Funding program

The second use draws inspiration from the 'proof of concept' funding programs of the U.S.

National Science Foundation in 1970s [START_REF] Kispert | An evaluation of methane production from solid waste[END_REF]. Indeed, it is not uncommon for governmental (for example, 'BRIDGE Proof of Concept' from the Swiss National Science Foundation) and intergovernmental agencies to offer 'proof of concept' grants (for example, 'ERC PoC 2019' or 'ERC PoC 2020' from the European Research Council in the framework of Horizon 2020 program, the E.U. research and innovation funding program). On the French portal of the Horizon 2020 program, it is explained that such grant is offered in order to support the researchers who develop ideas to be able to reach the market and cross the 'valley of death' of innovation. Several universities also support 'proof of concept' activities thanks to challenge funds [START_REF] Mosey | From human capital to social capital: A longitudinal study of technology-based academic entrepreneurs[END_REF]. These funds can come from University Technology Transfer Offices (UTTOs) [START_REF] Markman | Entrepreneurship and university-based technology transfer[END_REF] or 'PoC Centers' which help researchers in "the development and verification of a commercial concept, the identification of an appropriate target market, and the development of additional required protectable IP" [START_REF] Maia | The role of a Proof of Concept Center in a university ecosystem: an exploratory study[END_REF]. The general objective of these grants and incubation programs that sometimes use the Online, 3-5 juin 2020 reference of TRL 3 is to bring universities and research organizations results closer to the industrialization and commercialization.

NEW PRODUCT DEVELOPMENT, INNOVATION AND ENTREPRENEURSHIP

The 'proof of concept' is often used to describe an early phase in New Product Development (NPD) process (Clarysse, 2007;[START_REF] Heirman | Which tangible and intangible assets matter for innovation speed in start-ups?[END_REF] and innovation processes [START_REF] Bendavid | A 'living laboratory'environment for exploring innovative RFID-enabled supply chain management models[END_REF] in line with the NASA' Phased Review Process. The transfer occurred in the 1980s and early 1990s [START_REF] Cooper | Third-generation new product processes[END_REF] probably due to the large representation of TRL scale' users within the circles of technological management diffusion. In the definition of 'proof-ofconcept' given by [START_REF] Bendavid | A 'living laboratory'environment for exploring innovative RFID-enabled supply chain management models[END_REF], i.e., the demonstration of the technical feasibility of the concept, one can easily see the footprint of NASA's TRL 3 definition here.

Moreover, as materiality is needed to perform a POC, its occurrence very often goes together with the term 'prototype', and even sometimes the two terms are combined to form a unique concept: 'proof of concept prototype' [START_REF] Yu | Prototyping in theory and in practice: A study of the similarities and differences between engineers and designers[END_REF].

'Proof-of-concept' is also used to describe a new firm's development stage [START_REF] Eesley | The contingent effects of top management teams on venture performance: Aligning founding team composition with innovation strategy and commercialization environment[END_REF].

Moreover, with the birth of the startup phenomenon in early 2000s, entrepreneurs have massively embraced this wording and practice because of its powerful attractiveness, especially towards potential investors [START_REF] Eesley | The contingent effects of top management teams on venture performance: Aligning founding team composition with innovation strategy and commercialization environment[END_REF]. With such label, entrepreneurs hope to attract and convince them that the concept and the business is worth investing in while providing early evidence of success. This evidence of success can be related to technical or business/market issues. For instance, it is recognized that investors such as Venture Capitalists (VCs) prefer to invest in a technology that has proven its technical feasibility (Clarysse et al., 2017). Moreover, POC enriches market survey that has its limitation regarding radical innovations for which functional requirements remain to be conceived. The POC will help to determine them through the test of pseudo-solutions on pseudo-users. In the context of B2B or B2BC start-ups, entrepreneurs also aspire to attract potential clients through a 'proof of concept' contract, sometimes paid, sometimes free. These clients are often large groups given the market and the promotional image that can represent to the start-up and the widespread practice of open innovation in large groups (Chesbrough, 2003, Weiblen and[START_REF] Weiblen | Engaging with startups to enhance corporate innovation[END_REF]. According to Bpifrance, the French public investment bank, on the side of start-ups, POC is an opportunity to "generate revenue by acquiring customers [and] to engage quickly with large groups, with few technical constraints, and demonstrate the value of a start-up's services" while on the side Online, 3-5 juin 2020 of large groups, POC "allows to assess the capacity of the solution to meet the expectations of the large group and to see whether collaboration between the two stakeholders can be considered on a larger scale". In addition, 'proof of concept' is increasingly found in support structures such as (corporate) incubators and accelerators to depict either an entry or an exit point in the same line of NASA's Instrument Incubator Program. In addition, the POC is not confined to cases of entrepreneurship but also applies to cases of intrapreneurship. In that case, the target audience of the POC is internal to the company. Performing a 'proof of concept' study can help intrapreneur "selling the initiative internally and justifying funding" [START_REF] Hienerth | Exploring the nature and implementation process of user-centric business models[END_REF] similarly to entrepreneurs or generate internal feedback before presentation to the client.

Finally, the POC is increasingly represented in the world of design thinking [START_REF] Brown | Design thinking[END_REF]2009) and design sprint [START_REF] Knapp | Sprint: How to solve big problems and test new ideas in just five days[END_REF]. Even if this term is very weakly present or even absent from the original texts and seems to appear from nowhere, it has a real stake and interest in the contracting between design agencies and their clients in a reverse view of NASA and its contractors/suppliers. Indeed, the POC was also appropriated by SMEs such as 'les Sismo', a French independent industrial design and innovation agency. Les Sismo began to use the POC term to put a word on existing practices in the late 2000s. Then, les Sismo embrace the POC in the mid-2010s to characterize a service that can be sold to clients through a quote and therefore to ensure a remuneration while the final innovation is still under design.

INFORMATION TECHNOLOGY (I.T.): IMPLEMENTATION AND SECURITY

Finally, we also find 'proof-of-concept' in the context of implementation and security management, as in I.T. industry.

I.T. Implementation

Some companies which are looking for implementing a new software or I.T. solution do not content themselves to base the choice-making process of publisher solely by on fact sheets, presentations, or 'off-the-shelf' demos. They engage with potential suppliers through a POC in a similar manner that NASA does with contractors, or large companies with start-ups. Indeed,

IT Security

The transfer to the I.T. security ecosystem is probably old because the experts in cybersecurity (i.e., defense and aerospace/aeronautic companies) are the same that first embrace the proof-ofconcept terminology. Nevertheless, POC meaning is here more distant : Proof-of-concept is used to stress the vulnerability of an I.T. system to a (potential) cyber-attack or characterized the program or system that revealed this vulnerability or security breach [START_REF] Wilson | Bugs in the system[END_REF]. Such security vulnerability can constitute an entry point for a malware capable of altering the DNA of the software or I.T. system and thus reprogramming it to divert its initial use or crashing it. The defect can be identified by developers or security experts before its release or by attackers after its release. Contrary to the numerous tests required to characterize an I.T. solution as 'attack-proof', a proof-of-concept only needs to work once and do not call more development (e.g., optimization) than those requested to achieve the intended purpose. Proofof-concept initiative aims to raise awareness about the existence of such a flaw and thus an opportunity or the rest to be done to correct it [START_REF] Wilson | Bugs in the system[END_REF].

CROSS-DOMAIN STUDY ANALYSIS OVERVIEW

In Figure 3, we provide an overview of this cross-domain analytical study that described transfers of 'proof-of-concept' in other ecosystems than the U.S. aerospace and aeronautic. As a reminder, we seek to address the two following questions in the paper: (1) Where does the concept of 'proof-of-concept' come from and how has it evolved over time? (2) How does 'proof-of-concept' relate to a peculiar category of proof?

We showed that the 'proof-of-concept' was born in the 1960s in the U.S. aerospace and aeronautics ecosystem to organize resource allocation and drawing contracts with research and development partners, with the strong objective of putting a man on the Moon before the end of the decade. We saw that the concept was then used in contexts where there was a need to agree on the object of the transaction, in particular to reassure mission planners about the level of evidence achieved by the technology before allowing its transfer and integration into a future mission. A proof was therefore needed even if it could only be partial, knowing that the complete system was not yet there, and the tests were not carried out in the operational environment. We found this same logic of partial proof, or 'double proof', proof of validation and proof of exploration in transfers in the various ecosystems under study. It is quite easy to Online, 3-5 juin 2020 see a correlation between the appropriation of the POC by an ecosystem and an opening logic of the value chain that occurred. Thus, it is likely that the POC makes possible the entry of new actors. What is rather surprising is that this is not an entry through the downstream, which is rather usual, i.e., a company A handles the entire design and development process and then delegates the manufacturing to a company B. In the context of NASA and transfers, it is rather an entry through the upstream. It is about contractualization management knowing that the design activities have not yet been completed. The POC seems therefore to enable the disintegration of design value chains. When resource allocation or contracting processes already existed, they absorbed the POC while for those, such as public research, who did not, they adopted the TRL scale. While the exploratory nature of the proof is not easily identifiable in NASA's POC; to that end, one must look at the entire process, the articulation of these two types of proof is more easily palpable in the information systems ecosystem.

Characterizing the proof-of-concept as a double piece of proof could help to better position this object relative to other concepts that may appear in the first place as synonyms and are often used interchangeably. Among these terms, we think on the one hand of the 'test bench' or the 'prototype' (in the sense of a validator, see Ben Mahmoud-Jouini and Midler, 2019) or which are only oriented towards proof of validation. On the other hand, we can distinguish the POC from the 'mock up', 'concept car/object' or 'stimulators' (ibid.) which are rather centered on proof of the need of further exploration as these boundary objects reveal problems, make desirable the learning, etc.). As for the concept of 'demonstrator' (ibid.), the difference with the POC is more ambiguous because it contains both a demonstration logic (in the almost mathematical sense) and an exhibition logic (of the unknown). The POC might be distinguished from the demonstrator thanks to its supposed ability not only to gather proof of validation and proof of exploration but also to articulate both. We saw in this paper that the POC was mobilized in contexts where there were strategic issues regarding the design and evolutions of its value chain, and most often upstream. In this sense, the POC has emerged as a particularly useful tool in crystallizing the intermediate stages of knowledge and relationships. The POC has also appeared in this paper as a powerful tool for decision-making thanks to its time pacing effect and the robustness and mastery it brings, even in contexts where uncertainty or even unknown are very present. As such, the POC seems to be part of limited small number of objects that are capable of supporting decision-makers in highly exploratory contexts. This paper does have limitations that need further study to address them. Additional work in the dating of transfers deserves to be done to validate our conjecture. Even more, descriptions of transfers especially in the I.T. ecosystems need to be better supported by academic references. For those which are starting to be corroborated, it would be interesting, in the manner of cladistic phylogeny, to demonstrate more finely the common ancestries and go back to the closest of the transfer time. In addition, in the discussion, we started very succinctly to position the POC in relation to other 'synonyms'. Further research could likely deepen this investigation to better characterize the overlapping areas between POC and these other objects (e.g., experimentation (Thomke, 2003, Gillier and[START_REF] Gillier | Experimenting in the unknown: lessons from the Manhattan project[END_REF] as well as what makes the specificities of the POC. Continue to investigate the thesis that we began to sketch in this article is a stimulating perspective : in particular, we strive to study how the POC can not only concatenate proof of validation and proof of exploration but go further by articulating both and thus obtaining synergistic phenomena.

Figure 1 :

 1 Figure 1: Historical perspective overview

Figure 2

 2 Figure 2 clearly shows. .

Figure 2 :

 2 Figure 2: Google NGRAM graph of 'proof of concept' (literature between 1950 and 2008 from the corpus 'English (2012)')

  it allows the client company to both have a first sight on the future efficiency, compatibility, and user acceptability of the solution, and on the reliability and capability of the potential supplier. As for the other sectors, this transfer probably took place in the 1980s-1990s when companies have undertaken large waves of outsourcing of their I.T. by entrusting external XXIXe Conférence Internationale de Management Stratégique 21 Online, 3-5 juin 2020 companies such as IBM. Since the rise in capacities of these same companies which has become proposal forces as well as the emergence of start-ups specialized in breakthrough I.T. technologies in the 2000s-2010s, the proposal to conduct a POC only comes from the I.T. company which would like to prospect clients by reassuring them about the value and feasibility in applying their cutting-edge technology (Big data, IA, blockchain, IoT, …) into use cases of interest for the prospect. The POC can then mark the beginning of a broader collaboration between companies and even a co-design collaboration.

Figure

  Figure 3: Cross-domain analytical study overview

  Figure 4 underlines this dual function of proof managed by POC concept.

Figure 4 :

 4 Figure 4: The dual proof function of POC

Table 1 : Analysis of the first stakeholders who embrace the terminology of 'proof-of-concept' in academic literature (before 1980)

 1

	INSTITUTION	AUTHOR'S(S') POSITION	Use of POC Concept
	/ SUB-	(Year) * TBD: To be defined	(Quote / reference)
	INSTITUTION
	U.S. Federal Agencies
	National Aeronautics and Space Administration
	Ames Research Center	Manager of Advanced VTOL Projects Office & Research Leader of STOL joint flight programs (1973)

"A candidate V/STOL research aircraft design is one that features a promising V/STOL propulsion/control concept, is suitable for

proof-of-concept flight investigations, and

  fullscale engines are needed to quantify the achievable levels as well as to evaluate the impact of increased complexity on engine operational characteristics ... Rudey, R. A. (1976), The Impact of Emission Standards on the Design of Aircraft Gas Turbine Engine Combustors,SAE Transactions, 2838-2849.

	Langley Research	Chief of the Research Aircraft Flight Division, Aerospace Engineer, & TBD
	Center
	Lewis Research	Project Manager (1976)
	Center
		Chief of General Aviation Technology	"and Avco-Ly coming, are carrying out the development of a system for proof-of-concept testing
	Headquarters	Office & TBD (1976)	..."
		Winblade, R. L., & Westfall, J. A. (1976), NASA General Aviation Research Overview-1976, SAE Transactions, 1576-1650.
	Jet Propulsion Laboratory (California Inst. of	Geophysical Evaluation Manager, TBD, & TBD (1979)
	Tech.)

meets the objectives of austerity and maximum ..." Deckert, W. H., & Holzhauser, C. A. (1973), Evaluation of V/STOL Research Aircraft Design, SAE Transactions, 3122-3127. "... for FAA proof-of-concept evaluations ..." Reeder, J. P., Taylor, R. T., & Walsh, T. M. (1974), New Design and Operating Techniques for Improved Terminal Area Compatibility, SAE Transactions, 1714-1731.

Final proof-of-concept type tests in

Table 2 : Synthesis of NASA's uses of TRLs (adapted from Straub et al., 2015) TITLE OF THE DOCUMENT PURPOSE OF THE DOCUMENT OR ASSOCIATED PROGRAM PURPOSE OF TRL SCALE

 2

	NASA Research	Develop technology activities leading	Framework to evaluate proposals that must
	Announcement for	to new systems and measurement	provide the current TRL assessment of the
	the Instrument	techniques to be developed in support	system technology, and the anticipated
	Incubator Program -	of ESE science research and	progression of TRL levels throughout the
	NRA 01-OES-xx	applications.	proposed efforts -starting and exit TRL
	(2001)		must meet NASA Research
			Announcement policy.
	NASA Risk-	Provide guidance for implementing the	Risk and uncertainty assessment
	Informed Decision	risk-informed decision making	framework for mission analysis.
	Making Handbook -	requirements of NASA Procedural
	NASA/SP-2010-576	Requirements document.
	(2010)
	NASA System Safety	Present the overall framework for	Help whether the system design meet the
	Handbook -SP-	system safety to provide the general	minimum tolerable level of safety or
	2010-580 (2011)	concepts needed to implement the	vulnerability to unknown hazards.
		framework.
	NASA Strategic	Provide a focused investment approach	Guide NASA's technology investment
	Space Technology	to guide NASA's space technology	strategy and portfolio execution though a
	Investment Plan	investment over the next four years	principle that impel to have a balanced
	(2012)	within the context of a 20-year horizon.	investment across all TRL
	NASA Systems	Clearly articulate and establish the	Accurate assessment of technology
	Engineering	requirements on the implementing	maturity throughout the life cycle of the
	Processes and	organization for performing systems	project and capabilities to moving to
	Requirements -NPR	engineering.	higher TRLs.
	7123.1B (2013)		A differentiated description of technology
			maturity between hardware and software is
			proposed in appendix.
	NASA Systems	Provide general guidance and
	Engineering	information on systems engineering
	Handbook -	useful to the NASA community.
	NASA/SP-2016-6105
	Rev 2 (2016)

Online, 3-5 juin 2020

been aimed at "proof-of-concept" experiments, demonstrations and field tests designed to reduce the uncertainty for the commercial sector and to offer compelling educational evidence to the academic community ..."

event fostered the revision of the U.S. national space policy that President Reagan approved