2. The Macrostructure of the Overall Debate

The analysis of the CE controversy carried out hereunder uses placeholders. Instead of referring to specific CE methods, the reconstructed arguments speak generically of the CE technology “T” – which, later, must be specified when evaluating the argumentation. The central thesis of the controversy holds that R&D into the CE technology T ought to be carried out immediately (T1). This R&D obligation is contradicted by the R&D prohibition thesis T6. The central justification of research obligation T1 relies on three further theses:
[T2 Readiness for Deployment Desirable] The CE technology T should be ready for deployment at a future point in time.
[T3 Side-Effects of R&D Negligible] The side-effects of R&D into the CE technology T under the aspect R are negligible as compared to T being [probably] ready for deployment in time.
[T4 No Alternatives to R&D (Readiness)] There are no more appropriate alternatives to immediate R&D into the CE technology T under the aspect R which bring about that T is probably ready in time.
Each of these theses ignites a more or less extensive sub-controversy. In these sub-controversies, the contentious thesis that mitigation policies have priority over CE methods is of decisive importance (T14). Moreover, the R&D prohibition thesis is being justified through an alternative argumentation that does not require the controversial thesis T2. Finally, the CE controversy also contains direct justifications of the R&D prohibition.

1As already indicated in the introduction, the term “climate engineering“ subsumes various different technologies which all aim at large-scale interventions in the climate system, but which, at the same time, substantially differ from one another regarding risks, effectiveness, side-effects, and costs of deployment. Since these aspects are also relevant to the moral assessment of the corresponding technologies (i. e. of their R&D and deployment), the following problem arises for the argumentative analysis: To do justice to the different CE technologies, the question of whether, for instance, ocean fertilization should be further researched into would have to be discussed separately and independently from the question of whether, let’s say, cloud-albedo enhancement should be researched into as well. This applies, mutatis mutandis, to the remaining technologies as well. Accordingly, not only one but a rough dozen CE controversies, each dealing with a different technology, would have to be differentiated and reconstructed. Since the results of such an analysis would be extremely comprehensive and, in addition, redundant in many respects, this study uses a placeholder method (cf. Section 1.3).

2The central theses of the CE controversy, which directly address the key questions of the debate (see Section 1.1), and their logico-argumentative interrelations can be outlined as follows. The thesis

● [T1 R&D Obligation] R&D into the CE technology T under the aspect R ought to be carried out immediately.

3answers the central R&D question positively. It is contradicted by the thesis

● [T6 R&D Prohibition] R&D into the CE technology T under the aspect R must not be carried out.

4Three further theses fuel the central justification of the R&D obligation (T1), as Section 3.1 explains in more detail.

● [T2 Readiness for Deployment Desirable] The CE technology T should be ready for deployment at a future point in time.
● [T3 Side-Effects of R&D Negligible] The side-effects of R&D into the CE technology T under the aspect R are negligible as compared to T being [probably] ready for deployment in time.
● [T4 NO ALTERNATIVES TO R&D (READINESS)] There are no more appropriate alternatives to immediate R&D into the CE technology T under the aspect R which bring about that T is probably ready in time.

5Taken together, the three theses T2-T4 constitute a sufficient reason for R&D into the CE technology T. Reversely though, each of these theses represents a necessary condition for R&D obligation, as pointed out in Section 3.1: Should one of these theses be false, it would be wrong to carry out R&D into technology T, at least as regards achieving readiness for deployment.

6Theses T2-T4 are the starting points of more or less comprehensive sub-debates of the CE controversy. Based on these theses, the overall debate can thus be clearly structured into sub-controversies.

7The expected R&D side-effects and their assessment are the subject of the sub-debate that is associated with T3. Within that part of the debate, the side-effects of R&D are weighted and compared to the target of achieving readiness of deployment (cf. Section 3.2).

8Thesis T2, according to which readiness for deployment at a future point in time is desirable, triggers the most comprehensive sub-debate of the CE controversy (see Section 3.3). It contains various pro and con arguments of different types. These arguments are either directly related to thesis T2 (i. e. support or attack it) or back up the assumption

● [T9 CE Deployment Wrong] A future deployment of the CE technology T is in any case (morally) wrong.

9T9 is closely connected with T2: If T9 were true, then T2 would be false – for why should technologies whose deployment would be morally wrong be ready for deployment in the first place? The arguments supporting thesis T9 thus indirectly attack T2.

10T4, too, appears to be contestable (cf. Section 3.5.1). According to the findings of the authors, though, hardly any arguments have been put forward so far in order to settle the question whether there are no alternatives to immediate R&D, should the appropriate CE technologies be ready for deployment in time. The thesis T4 is only challenged by few arguments.

11Irrespective of the issue of the future readiness for deployment, several further reasons are given in favour of the R&D obligation T1 (cf. Section 3.4). These alternative justifications do not depend on the highly contentious thesis T2 and, thus, circumnavigate the most comprehensive sub-controversy of the overall debate. However, the alternative justifications of T1, too, make use of premisses that, in line with T3 and T4, hold that R&D side-effects are negligible and that there are no alternatives to immediate R&D. T3 and T4 thus turn out to be the actual touchstones of any position whatsoever which embraces R&D into CE technologies.

12The critique of R&D into CE technologies is not limited to attacking theses T2-T4. Independent of the objections to T2-T4, T6, which proscribes R&D, is supported by a number of ethical arguments that have already been discussed in some detail in the current debate (see Section 3.5.2).

13Another important thesis which, although conceded by most of the proponents, mainly supports the arguments of the critics, asserts that mitigation policies, which try to prevent anthropogenic climate change through emission reduction, have priority over CE measures.

● [T14 Mitigation First] Mitigation, as a climate policy option, is preferable to CE deployment.

14Thesis T14 represents the starting point of various arguments in the CE controversy (cf. Section 4.3) and can itself be justified in different ways (see Section 3.5.4).

15In line with the above, the macrostructure of the entire reconstructed CE controversy can be visualised as follows.

Argument Map A: This map visualises the overall structure of the reconstructed CE controversy. Besides central theses (framed boxes), it mainly displays argument clusters, which group individual arguments. The argument clusters represent sub-debates of the controversy and exhibit a more or less complex internal argumentative structure. Argument clusters are numbered corresponding to section numbers in this book. Green and red arrows indicate argumentative impacts (supportive or critical) of the reasoning set forth in the corresponding sub-controversies.