Abstract
Introduction
Diligent citizens must critically analyze arguments for science policy recommendations, such as cutting greenhouse gas emissions or growing genetically modified food crops. Science policy articles present arguments for and against such recommendations using scientific evidence and rhetorical devices. In this paper we present an in-depth analysis of argumentation and rhetorical devices in two journal articles on climate change issues [10,11]. The articles present policy recommendations to a science/technology-literate audience. We represent the propositional content of the main arguments and the rebuttals to potential counterarguments. In addition, we identify the rhetorical devices used in these arguments. Rhetorical devices can make text more salient, more engaging, evoke an emotional response, or convey an argument in abbreviated form [4]. In fact, rhetorical devices play a key role in the
One objective of the analysis was to gain a better understanding of use of rhetorical devices in this genre, as a prerequisite for designing and building a rhetorically-annotated digital corpus of full-text science policy articles. An in-depth analysis was necessary since we had found no published computation-oriented rhetorical analyses or rhetorically-annotated digital corpora of science policy articles. (See the next section on related work.) In the future the corpus could be used, e.g., for computational research on rhetorical figure detection, argument mining, and persuasion. The results of that research could, in turn, support a new generation of tools to help citizens to evaluate science policy proposals. In the near term, the analysis was intended to serve as a starting point for the design of an educational system to help students analyze science policy arguments.
A number of educational computer systems have been developed to support development of argumentation skills [12,19,20]. Some educational systems support argument comprehension through the use of argument diagramming, e.g. [14]. However, an argument’s presentation in a text, including its use of rhetorical devices, may influence its persuasiveness. The ability to recognize rhetorical devices is important, since studies have shown that students may favor presentation style over content in evaluating argument strength [3]. Yet pedagogical support for analysis of rhetoric has largely been neglected in educational argument systems. The exception is use of linguistic text analysis tools to help students visualize the role of lexical repetition and semantic relatedness in straw man arguments [18]. Lexical repetition and semantic relatedness are but two of many types of rhetorical devices. Thus, our near term goal is to develop an educational system that supports not only argument diagramming but also identification of a variety of rhetorical devices in science policy articles.1 The system is not intended for use in creating an annotated corpus; thus, the student would not be required to learn or apply annotations schemes. (One might use student analyses as a stepping stone towards that end, but that is not our goal.) Also, it is beyond the scope of our current work to develop an intelligent tutoring system that could evaluate the student’s work and provide automatic feedback. To develop such a system would require a “gold standard” annotated corpus, which does not exist currently. The current goal is simply to provide graphical user interface tools for students to record and visualize their analyses.
The natural language processing research literature has overloaded the term
The rhetorical devices identified in our analyses are based on descriptions in two recent studies in
There are no corpora of full-text science policy articles in which rhetorical figures have been annotated for computational research. Note that RhetFig [8] does not provide a corpus of annotated full-text articles; instead the goal was to provide multiple examples of each figure from a variety of sources. A limited amount of research has been done on automatic detection of rhetorical schemes and tropes; for surveys see in [9,13]. Researchers have begun to investigate how automatically detected rhetorical figures could be used for argument mining [13].
Ocean acidification article
An article by Johnson and White [10] concerns the problem of increasing ocean acidification (OA). The structure of the argumentation in the article is shown in Figs 1–3. As shown in Fig. 1, the main policy recommendation is for the reduction of emissions of carbon dioxide into the atmosphere, which is expressed in the last paragraph (¶21) of the article. We analyze the main argument for that recommendation as an instance of a Value-Based Practical Reasoning scheme [1,6,21]. Values underlying the argument include nature’s beauty, biodiversity, protection of the marine environment, food security, human health, and economic security. The premise that increasing atmospheric carbon dioxide is causing an increase in ocean acidification is given in ¶3 and supported by instances of Argument from Cause to Effect and Argument from Correlation [21] given in ¶3 and ¶4. The premise that increasing OA is a serious problem is given in ¶4 and supported with evidence in ¶5–14. Five counter-arguments and their rebuttals (represented as boxes in Fig. 1 labeled 1–5) are shown in Figs 2 and 3.

Main arguments in “Ocean acidification: The other climate change issue”.

Rebuttals 1–3 in “Ocean acidification: The other climate change issue”.

Rebuttals 4–5 in “Ocean acidification: The other climate change issue”.
Although ¶3 and ¶4 play a role in the policy argument described above, the untitled opening section of the article (¶1-4) also plays a large role rhetorically. As noted in analyses of other environmental writing [16], the introduction first engages the reader with a fable-like warning of environmental catastrophe. Consider ¶1:
As a whole this paragraph can be interpreted as an enthymematic Value-Based Practical Reasoning argument, expressing the premise that some ocean species are threatened by changes in ocean chemistry, and through word choice (
Consider ¶2:
The fable-like style continues in ¶3, beginning with a left-branching syntactic construction and referring to an historical event (
The fable continues in ¶4 with another historical reference (
Compared to the introduction, the body of the article (¶5–19), which describes the causes and consequences of OA in scientific detail, uses few rhetorical devices. However, the relatively high frequency of phrases containing the root ‘acid’ (
¶15 contains a rhetorical question (
The use of rhetoric picks up in the last section (“Safeguarding Ocean Chemistry”, ¶20–21), which contains two counterarguments and their rebuttals (see boxes 4 and 5 in Fig. 3). One rebuttal (¶20) is an instance of the rhetorical argument of Protocatalepsis, paraphrased in large font outside of the body of the text (
An article by Keith [11] argues in favor of research on solar geoengineering, “a process by which humans might deliberately reduce the effect of heat-trapping greenhouses gases, particularly carbon dioxide, by reflecting a small fraction of sunlight back to space.” The argumentation structure for that proposal is shown in Figs 4–6. As shown in Fig. 4, in ¶1–6 of the untitled opening section, the article gives an argument for employing solar geoengineering, combined with cutting greenhouse gas emissions, as a means of reducing global warming. This recommendation, in turn, is a premise of an argument for beginning research on solar geoengineering in the rest of the section (¶6–10). We have labeled the argument for research as V-B PR (Value-Based Practical Reasoning) Knowledge Precondition since the recommendation for the action of beginning research arises from the knowledge precondition [2] to know more about the technology before it can be deployed. Numerous counter-arguments to the two recommendations are shown in Figs 5 and 6.

“Towards a responsible solar geoengineering research program” introduction (¶1–10).

“Towards a responsible solar geoengineering research program: Reasons for reluctance”.

“Towards a responsible solar geoengineering research program: Reasons for reluctance” (continued).
As in the article discussed in the previous section [10], the untitled opening section of [11] (¶1–10) also plays a large role rhetorically. The third paragraph contains a rhetorical argument of Prolepsis as Presage for research on solar geoengineering (shown in Fig. 4). The argument is made more salient by use of a compound figure of parison and antithesis (
The longer, sixth paragraph details the cost-benefit of research on solar geoengineering compared to the cost of global warming. The phrase
The next section of the article (“Reasons for Reluctance”) provides numerous rebuttals to potential objections to the recommendation to begin research on solar geoengineering (see Fig. 5) and to the recommendation to use solar geoengineering combined with emission cuts (see Fig. 6). Like the opening, this section is rich in rhetorical devices.
Under the subheading “Uncertainty”, the objection that it is risky to use the technology since it cannot be tested before it is actually deployed (Fig. 6) is addressed in ¶12-14. Rhetorical questions (
Under the subheading “Slippery Slope”, ¶15 addresses the objection that once research has begun, it will not be possible to prevent deployment of solar geoengineering technology (Fig. 5). This objection is expressed with a rhetorical figure of antimetabole (reversal) (
Under the subheading “Messing with Nature”, the next two paragraphs (¶17–18) address the objection that we should preserve nature (Fig. 6). The first rebuttal indirectly attacks holders of that view, calling it “a particularly North American nineteenth-century view”. The second rebuttal is that use of solar geoengineering is comparable to other environmental restoration programs that are regarded positively. This is expressed via rhetorical questions, sarcasm, and analogies:
Under the subheading “Moral Hazard”, ¶21–23 address the concern that research on solar geoengineering will weaken public support for cutting emissions (Fig. 5). In ¶21, in a figure of conciliato, the author identifies with others who have raised this concern (
A second rebuttal, in ¶23, is that learning about solar geoengineering may increase the public’s awareness of climate risks and thus increase commitment to emission cuts. This is expressed first by presenting two “extreme reactions” in the form of satirical statements from imaginary members of the public, e.g.,
The final paragraph of the “Reasons for Reluctance” section (¶24) concedes that although “each of the concerns described above has merit” they are not sufficient to defeat the arguments for research (Fig. 5) or on use of solar geoengineering (Fig. 6). Also, as shown in Fig. 6, it repeats the proleptic argument that
Instances of some of the rhetorical devices in the two articles
There are some interesting similarities and differences in the use of rhetorical devices in the two articles. The introduction and ending of both articles make heavy use of rhetorical devices. Although both articles employ proleptic figures, by its use of a fable the introduction of [10] seems designed to appeal to emotion more so than the introduction of [11]. Another similarity is that rhetorical devices are associated with rebuttals in both articles. However, in [11] rebuttals are expressed in a more adversarial style than in [10], e.g., using rhetorical devices of irony, sarcasm and satire.
A primary objective of the analyses was to gain a better understanding of uses of rhetorical devices in this genre, as a prerequisite for designing and building an annotated corpus of full-text science policy articles for computational research. The analyses demonstrated usage of a wide range of rhetorical devices (some of which are listed in Table 1) that we intend to annotate in our first version of the corpus.2 It is not yet clear which rhetorical figures should be annotated. Other computational researchers focused on a small set with “clear linguistic signaling” [13]. On the other hand, many of the figures illustrated here which, intuitively, play a role in the persuasiveness of the articles are not so clearly signalled. Another consideration is whether a figure can be described precisely enough to achieve high inter-rater agreement by corpus annotators.
Unfortunately, the two analyses failed to suggest how detection of rhetorical figures would be of much assistance in automatically extracting the main arguments shown in Figs 1 and 4 by current surface feature-based machine learning approaches to argument mining. Such an approach assumes that (1) after a text has been segmented into uniform units such as clauses, each segment can be reliably labeled (by human coders) as premise or conclusion (or neither) of an argument; and (2) that the presence of certain rhetorical figures within that segment correlates with the labeling of the segment. However, the first assumption does not hold in these two science policy articles. The propositional components of the arguments are expressed in sometimes non-contiguous, at times widely separated, or sometimes overlapping text segments of varying granularity, as was previously noted for bioscience research articles [7]. Another possible use of rhetorical features in argument mining would be, given that a block of text (multiple contiguous text segments) has been identified as expressing an argument, to identify the argument scheme. In the articles that we analyzed, since many common rhetorical devices were used within the main Practical Reasoning arguments, it is not clear that any of those devices uniquely correlate with that argument scheme. Nevertheless, we do not mean to discourage future argument mining research exploiting rhetorical device detection in this genre. For example, the role of rhetorical figures in detection of rebuttals merits further exploration.3 Fahnestock has argued that a rhetorical figure may epitomize an argument [4], i.e., convey it in abbreviated form. It is not clear yet how to reconstitute the argument underlying a figure using state-of-the-art computational techniques, but that is also an interesting problem for future research.
The near term objective of this study was to aid in designing an educational system to support a student’s analysis of both argumentation structures and rhetorical devices in science policy articles. The analyses presented here provide use cases for the design. As shown in Figs 1–6, the system must support a student’s creation of large and complex argument diagrams that feature chains of arguments, multiple arguments for the same conclusion, use of argumentation schemes, and rebuttals. Diagramming techniques used in current educational argument systems could be adapted for this. At the same time, the system must support a student’s markup in the text of each occurrence of a large number of types of rhetorical figures, many of which are compound figures (overlapping the same span of text). This will require the system to provide an intuitive4 I.e., not the powerful but complicated sort of tool used by professional annotators for creating corpora. In the future, automatic figure detection could be used to supplement manual identification of figures by the student. Educators using the system could contribute their own analyses of science policy articles to a shared repository.
