While Jackson (2000) has asserted that systems thinking is, indeed, a new paradigm which could revolutionize management practice in the 21st century, Senge (1990) sees systems thinking as a discipline to change patterns of thinking. In recognizing the evolving broad church of systems approaches, Jackson (2000) has commented on the need to recognize communality and complementarity in the methodology and purpose of such approaches. He offers "critical systems thinking" as a coherent framework to unite diverse systems approaches, including chaos and complexity theory, the learning organization, SD, living systems theory, SSM, interactive management, interactive planning, total systems intervention, autopoiesis, management cybernetics, the viable system model, operations research (hard and soft), systems analysis, systems engineering, general system theory, socio-technical systems thinking, the fifth discipline, social systems design, team syntegrity, and post-modern systems thinking. However, Jackson, like most systems thinkers, fails to mention TOC as belonging to this broad church, despite most TOC authors (Goldratt, Dettmer, Scheinkopf, Cox et al., 2003) labeling TOC as a systems approach and stressing the importance of taking a systems view.

As such, we can view, for example, Checkland and Scholes' (1990) SSM or Beer's (1985) Viable Systems Model (VSM) of organizational structure and design as enquiry systems, as learning systems, where the methodology or model provide the conceptual framework to guide our inquiry and learning about the situation or organization at hand. In both these cases, the notion of purposeful systems looms large in the mode of inquiry. In SSM, assumptions about the nature and purpose of the system being examined are captured in a "root definition" stated in terms of its Customers, Actors, Transformation, Weltanschauung, Owners, and Environment (CATWOE). Any attempt at problem solving, therefore, takes place in the context of the system definition and purpose. Similarly, any use of the VSM to explore organizational effectiveness or the effectiveness of organizational design is made in the context of defined organizational purpose.

We note the similar importance of system goals or purpose in the effective use of the 5FS approach, the EC process, and more generally within TOC of identifying What to Change to? We also note the underpinning assumption in the development of GEC that the seemingly initial different worldviews of analysts can be accommodated in a single generic cloud. These matters beg the question, notwithstanding the importance of defining the system goal, of whether the system goal can be objectively defined or whether the system goal remains an ill-defined phenomenon whose definition and description varies according to the questioner/observer.

Other Decision-Making Tools

There are many other cause-effect based tools and decision-making models available, each of which has its advantages. For example, the Theory for Inventive Problem Solving (Altshuller, 1973), known by its Russian acronym, TRIZ, provides a useful method for generating solutions to dilemmas (or contradictions), and may be usefully employed in tandem with the EC (Mann and Stratton, 2000; Dettmer, Chapter 19 this volume). Why-Because Analysis (WBA) provides an alternative method of constructing a fault analysis to root cause, and has also been used in tandem with and compared with TOC5 (Doggett, 2004; 2005; Zotov et al., 2004). In addition, process mapping has also been used to aid CRT construction, and other techniques, including Lean, quality management, and process engineering, have been found to be mutually supportive of, and certainly not mutually exclusive of TP tool use (Watson et al., 2007).

Lessons for TOC from the Literature

Issues Emerging from the TOC Literature

Ronen (2005), in his guest editorial introducing the special issue on TOC published in the Journal of Human Systems Management, bemoans TOC's low profile in academic research journals, and offers some reasons why this may be the case: TOC is heuristic oriented, in line with Simon's et al. (1987) "satisficing." Many academic journals prefer process-optimizing, quantitative approaches, while the goal of TOC is simplicity.

TOC processes are cause-effect driven. Academic journals prefer field studies or empirical data.

TOC originated in practice-not enough academics have been exposed to its full contribution.

TOC is often misperceived as a simplistic toolkit that does not need thorough research.

TOC is viewed as a cult and thus inaccessible to the academic community.

Ronen called on academics to apply academic methodologies to TOC concepts and confirm or improve its methods, and to apply academic rigor to research on TOC. More specifically, Watson et al. (2007), in their "Silver Anniversary" review of TOC, identified two common problems with TP: The reliance on subjective interpretation of perceived reality and the qualitative nature of the subject matter makes the tools inherently unreliable, which leads to a perceived lack of reliability and validity in TP analyses.

The TP tools are criticized for not being user friendly.

These matters are outlined further in the next section.

The Nature of the TOC Literature Vis-a-Vis Other Literatures

We now comment more broadly on the nature of the TOC TP literature, its distinctiveness, and similarities and differences with the literature of other OR/MS and other problem-solving methodologies. In order for TOC to increase its visibility-and acceptability, especially within academia-there is a suggested need for TOC practitioners and academics to target publication of refereed journal articles and book chapters in edited volumes, to counterbalance the many non-refereed books and conference papers on TOC, to build that greater visibility and credibility.

However, and second, there is no one journal ideally suited for TOC or the TOC TP, although there are several obvious journals for production applications, projects, etc. As a result, published work as articles is spread across a range of journals, promoting widespread coverage but possibly reducing the impact that may come from there being a concentration, or home, in particular journals. Furthermore, as Kim et al. (2008) noted, the journals that published articles on TOC TP were generally those with lower impact factors, so targeting higher impact journals would be desirable.

Third, and unfortunately, while TOC would appear to share many characteristics with OR/MS, other systems methodologies, and soft OR, proponents of these methods do not generally consider TOC to be one of their kind, due to a lack of awareness, understanding, or through a more deliberate choice to exclude-an irony indeed, when one considers the history and plight of soft OR in seeking to gain acceptance in the more traditional OR/MS and journal mainstreams.

If the TP are to gain more recognition within academia, we must break into or join the journal mainstream, and despite the previous comments, the lowest barriers to entry may be through links with these comparator or peer disciplines. Indeed, Ronen (2005) has suggested that many TOC practices have their roots in well-accepted and well-established OR/MS concepts, which facilitates their multi-methodological use, for example, combining the 5FS and the mathematical programming approach in multi-methodological use. There have been several papers comparing TOC with LP, mostly showing congruence, but also showing advantages of using TOC. Indeed, there can be significant synergies in combining TOC with OR methods, as argued by Mabin and Gibson (1998), echoing criticism by Zeleny (1981) and Gass (1989) of naive usage of LP in relation to the management of constraints.

The reviews of the TOC and TOC TP literature reported here have been complemented by a useful series of retrospective/state-of-the-art reviews conducted for the 50th anniversary conference of the Operational Research Society, York, 2008, many of which are published in Brailsford et al. (2009). These included reviews on soft OR and PSMs (Rosenhead, 2009), Systems Thinking (Jackson, 2009), and healthcare (Royston, 2009).

What is noticeable and notable in these reviews is that TOC is absent, unrecognized, or excluded from descriptions of OR, soft OR, PSM, and systems methods as presented in such reviews. For example: The notable successful work at Radcliffe and Horton Hospitals by the Goldratt Group has been reported in Umble and Umble (2006) as well as in The Oxford Story, by Dr. Eli Goldratt, available on various websites,6 but this work is not included in the "One hundred year review of OR in health," despite it being published in a prominent OR journal.

TOC is not mentioned in the soft OR discussions of Mingers (2009a; b), despite being linked and compared in the Omega publication of Davies et al. (2005), and despite sharing many seeming commonalities in domains of application.

TOC is not generally referred to in OR texts, except sometimes for a small section on OPT, constraint management, or synchronous manufacturing aspects. Even in Operations Management textbooks, there is usually just one chapter on TOC, with a few notable exceptions such as Cox et al. (2003), which approaches the subject using TOC as the overarching framework.

Even though TOC work has been published in OR/MS and systems journals, it appears that TOC has yet to be considered mainstream or to provide a mainstream contribution to any of these disciplines. Nevertheless, the TOC community can do more than await recognition. However, before taking action appropriate to gaining that recognition, there would be benefit in conducting a self-audit. The following section offers some suggestions about matters that deserve consideration.

Suggested Topics for a Self-Audit of TOC

In the following subsections, we suggest much can be gained from a self-analysis of TOC as a field of learning and as a profession, and the role of TOC academics within the profession. The self-analysis should encompass the strategic role of publication outlets in gaining recognition for TOC, and which may best serve academics, practitioners and the wider community provided for by TOC. In a subsequent section, we also suggest that much can be gained by understanding the nature of TOC as a methodology.

TOC as a Profession

The TOC community is not alone in its experiences. There is a sense that much can be gained from looking inward and outward, and it can learn from the concerns and experiences of other professional groups. For example, OR in the United States has suffered from what Abbott (1988) termed "professional regression"-a process by which professions withdraw into themselves (Rosenhead, 2009, S13, quoting Corbett and van Wassenhove, 1993). Furthermore, status rankings, internal to the profession, based on the knowledge system that gives a profession its special claim, tend to be correlated with remoteness from practical concerns and implementation. Rosenhead asserts that the 1988 CONDOR report illustrated this tendency in OR.

At present, the TOC profession seems safe on this latter tendency, as TOC developments are strongly practice-based or practice-oriented (Inman et al., 2009). We suggest that the TOC profession should be aware of the risk of professional regression, but acknowledge that there is an inherent dilemma. On the one hand, if TOC wishes to gain credibility and recognition within and from other peer disciplines, it needs to conform to the academic rigor and norms of those peer disciplines. However, in order to do so, the TOC community must submit its body of knowledge to scrutiny using the same academic norms and protocols to which other academic peer groups are subject. If TOC fails to build support from other peer disciplines, it can run the risk of "professional regression." However, if TOC seeks to gain such support by uncritically adopting the methods of other disciplines, it may jeopardize TOC's focus on practical aspects that traditionally motivate TOC proponents and that fuel most of the developments within the TOC community.

Identity and the Strategic Role of Publication Outlet

The previous section has made implicit reference to the important issue of identity-both self-identity and the identity projected to others. In considering these matters further, we need to consider more broadly why TOC has not become accepted in the mainstream, and more specifically, why TOC is rarely mentioned in the academic and journal mainstream. One may suppose that TOC is not recognized as being OR or soft OR because of its very distinct parentage, and that many may still think of TOC as a scheduling or manufacturing method. We suggest that much may be gained from spreading the message appropriately, demonstrating that TOC is more than a set of tools for operations management. Constructive illustration of the TP in complementary or multi-methodology work, in other domains of application, may help build awareness and acceptance of the TP.

Even though TOC is not considered to be hard or soft OR, or a systems method by proponents of those disciplines, TOC TP contributions are already finding favor in the UK and in the European more practically oriented OR and systems journals such as the Journal of the Operational Research Society (JORS) or the international OR federation's International Transactions in Operational Research (ITOR). The journals Human Systems Management (HSM) and International Journal of Production Research (IJPR) have both published special issues on TOC. Maybe the time is right to explore similar outlets such as the Journal of Operations Management (JOM) following the success of Watson et al. (2007), European Journal of Operational Research (EJOR), Interfaces, and other INFORMS journals, especially given the currency of debate about soft OR; and especially so, if one may argue that TOC could be considered either as constituted in the same manner as other soft OR methodologies or considered as part of the soft OR community or domain. Indeed, since more support has been shown overtly, at the time of writing, for soft OR in the U.S. OR community, there may also be an increased readiness for publishing TOC papers within the U.S.-based journals.

Role for TOC Academics/Researchers

We may infer from the broader discussion of the literature, and prior comments, that there is a need for TOC academics and researchers to remain connected with practice, while building academic credibility through rigorous research. In this role, we may suggest that TOC academics should aim: to link, interpret, and comment on TOC knowledge and practice from an objective perspective; to further develop TOC knowledge in ways that embed TOC into extant academic disciplinary knowledge and leverage off those other disciplines; to enhance the academic qualities of TOC knowledge, and the status of TOC in academia; and to begin a dialog with TOC practitioners on these matters, in the hope that they will find such dialog valuable and useful, as they continually reflect on their practice as part of their own continuous improvement processes.

The next section provides a first step in satisfying these aims, in as much as it seeks to summarize, reinterpret, and build our understanding of the nature of the TOC TP, and TOC as a methodology.

The Nature and Use of the TOC Thinking Processes Revisited

Here, we subject the TOC TP and TOC as a methodology to examination using the classificatory frameworks of Mingers and Brocklesby (1997) and Mingers (2003). As such, we heed Ronen's (2005) call for more rigor in the TOC domain, and his call to establish the credibility of TOC, by providing an external perspective using the frameworks in a transparent and rigorous fashion. As a consequence, we also work toward Ronen's goal to close the gap between TOC and the academic world.

In the following section, we first draw on the M-B framework (1997) to provide an alternative perspective of different TOC methods and TP tools, by clarifying their role, function, and purpose. We are then able to relate the methods and tools, and broader TOC methodology to problem content and problem-solving activity-in order to provide a basis for selective comparison with traditional methods. In the subsequent section, we seek to surface and clarify the underpinning philosophical assumptions that support TOC TP, other TOC methods, and TOC as a methodology.

Understanding the Relationship of the TOC TP to Problem-Solving Activity

In Table 23-5, following the M-B classificatory approach, we characterize a selection of the TOC TP tools used within TOC using the descriptions of each of the tools and methods, as a basis for such characterization and classification (see full set in Davies et al., 2005).

The bolding of the TP tool name reflects our view that the tool was developed and designed for purposeful use in a particular phase of the problem-solving process, while the number of "+" signs indicates the extent to which the tool was designed to meet such purposes.

In an illustrative interpretation of the characterization, we note, for example, that the mapping of EC activity to the modified M-B framework (see Table 23-5) demonstrates how the EC method can provide an effective bridge from the problematic current situation to the desired future by contributing to all phases of intervention, but not necessarily across all problem domains.

Similarly, we note that the set of tools and methods of TOC are designed in a way that they may contribute across all phases of problem-solving activity including what we refer to as action or implementation.

In addition, the tools directly target or deliver on all but one of the cells in the M-B grid (see Tables 23-5 and 23-6), namely, the appraisal and evaluation of means of critiquing, contesting, or modifying power relationships in the social domain. In particular, we indicate, by the increasing darkness of shading in Table 23-6, the relative extent to which the collective set of TP tools is purposively designed to attend to each phase of problem intervention in each of the problem dimensions.

TABLE 23-5 Mapping Methodologies-TOC TP TABLE 23-6 Alternative Mapping of TOC as Meta-Methodology In explanation of such categorization, we refer to the protocols and criteria of the M-B classificatory system relating to purposeful design. We note, for example, that while some soft OR methods were expressly designed and developed with the purpose of setting out to contest or change power relationships and structures, we cannot say that the TOC TP were designed for that specific purpose. That fact notwithstanding, TP tools have and may be used to attend to such matters successfully.

Indeed, the TOC TP may not address such issues unless diagnosis (using, say, the CRT) points to the power structure as being a core problem, or unless the power structure is seen to be an obstacle during the development of the PRT. Even though such challenge to power structures may be an emergent property of the TOC approach, since TOC does not aim to do this from the outset, nor is it a natural common outcome, we have left this box unshaded to maintain consistency with Mingers' classificatory approach-which is that the classification of an activity requires that it is deliberately designed for that phase of intervention. Nevertheless, we may conclude that the characterization demonstrates that the TOC TP comprise what Dettmer calls the "complete package" and what we call a methodological set or meta-methodology.

The next section demonstrates how the related classificatory framework of Mingers (2003) may give rise to complementary insights.

The Philosophical Basis of the TOC TP

In Table 23-7, we provide an alternative characterization of each of the TOC TP tools and the 5FS method. In doing so, we again draw on the brief descriptions of each of the tools and methods as a basis for the characterization of the underpinning philosophical assumptions, using the classificatory system of Mingers (2003).

TABLE 23-7 Framework for Characterizing the Philosophical Assumptions underlying TOC Methods We note that when the underlying assumptions and purpose are to be presented in this manner, we need to gain clarity about for what purpose and how the tools may be best used, and we may then develop realistic expectations about the use of the tools. In addition, we also note and foreshadow the scope for complementary use of the tools with respect to addressing multipurpose or multiobjective problem situations.

In the following section, we will re-examine the tools and their purposes in terms of their contributions to the different phases of intervention in the problem-solving process. It is worth restating here that even though the tools and methods are often used on their own for day-to-day problems, they are often used in combination for more infrequent and complex situations as well (Kim et al., 2008). The nature of such use, and reasons for its success or failure, can be explored appropriately by reference to the characterization of TOC tools presented in Table 23-7.

Table 23-7 captures and represents succinctly the defining nature and nuanced purposes of the TOC TP. In doing so, it makes explicit, somewhat ironically, the often unstated, sometimes unrecognized philosophical assumptions that underpin the TP, the associated TP tools, and their use. Some such assumptions relate to beliefs about what exists-cause-effect relations-and what could be-continuous or breakthrough improvement-and are ontological in nature. Other assumptions relate to the nature of information available, how we may access such information, and how we represent and process it, via causal logic trees. These are epistemological in nature. Similarly, other assumptions or beliefs relate to what we may expect a TOC tool "to do," and to its axiological nature; that is, for whom the analysis is being conducted, and for what purpose the tool will be used. As such, Table 23-7 provides a different perspective on the TP tools, and on their development and use, especially the need to be cognizant of and in tune with the philosophical assumptions when seeking to use the tools appropriately and effectively.

Summary Insights from Classificatory Mapping of the TOC TP