1
Introduction and Challenges

Argumentation is a language activity that occurs in an interactive context. It is based on an underlying set of schemes of thoughts, processes and strategies. This chapter introduces the notions of argument and argumentation, and the basic organization of an argumentative discourse. These notions will then be developed in more depth in the chapters that follow. This introduction to argumentation is oriented toward argument mining, which is the main topic of this book, therefore it is not a standard introduction to argumentation. References will allow readers to deepen their knowledge of the theoretical aspects of argumentation.

1.1. What is argumentation?

According to Aristotle, argumentation is the ability to consider, for a given question, the elements that are useful to persuade someone. Argumentation was, at that period, closely connected to rhetoric, which is defined as the art to persuade an audience. The ancient Greek argumentation and rhetoric were mainly designed for political decision making. This is why they are essentially oriented toward debates and judiciary purposes. After a long period during which rhetoric and argumentation were disregarded because they were considered as the art of trickery, in 1958 C. Perelman and L. Obrechts Tyteca [PER 58] contributed to a renewal of rhetoric and argumentation. These disciplines got a more scientific analysis. They were viewed as the development of discursive techniques that aimed at increasing an audience's support for a given thesis. The approach was that the orator who is addressing an audience needs to take into account its values, opinions and beliefs.

In more technical terms, argumentation is a process that consists in producing articulated statements that justify a given claim. A claim C results in two standpoints: C and not(C). C can therefore be associated with justifications (supports) or contradictions (supports for not(C)). An argument is composed of at least two structures: a claim and a proposition that is a justification of the claim. Propositions (or statements) that justify the claim are called supports, while those which are against the claim or tend to disapprove it are called attacks. Supports as well as attacks can be more or less strong and direct with respect to the claim. A specific facet or part of the claim can also be attacked or supported, instead of the claim as a whole.

An important point to be highlighted when it comes to argumentation theory is the ambiguity of the word argument in English. D.J. O'Keefe [OKE 77] distinguishes between argument1, which refers to the reasons given for or against a point of view, and argument2 that has to be understood as equivalent to dispute1. There are also confusions between attacks or supports of a claim, sometimes called arguments. In what follows, an argument is a claim associated with a justification (or support) or an attack. Finally, the term argument also refers to the elements a verb or any predicate combines with such as a subject or an object. This sense of argument is not used in this book.

Claims can be almost any kind of proposition (or statement). They include forms such as thesis, judgments, opinions, evaluations, rhetorical questions, etc., whose goal is to put forward a debatable topic. Claims can be introduced by epistemic expressions such as I think, it seems, or performative verbs such as I pretend, I recommend and their nominalizations, which indicate that it is a personal position. A claim can be stated with a strong conviction or in a much weaker way as a possibility or a suggestion. Various operators express different levels of certainty, such as I am certain, I feel, it seems that. Such types of expressions are typical linguistic cues of a claim. Other forms of claims include evaluative expressions, as illustrated in example (1-1).

An argument is a complex structure composed of a claim and a set of propositions that (1) support or attack that claim or (2) support or attack other propositions in that structure, which are then considered as secondary claims. In this latter case, the aim is to reinforce the strength of the propositions related to the claim or to cancel out their effect, for example, via the attack of a proposition that supports or attacks the main claim. Supports and attacks define the polarity (i.e. for or against) of a proposition with respect to a claim. They suggest a bipolar analysis of arguments since only attacks or supports are considered.

For example, given the claim:

(1-1) Vaccination against Ebola is necessary,

statements such as:

(1-1a) Ebola is a dangerous disease,
there are high contamination risks,

are analyzed as supports, while:

(1-1b) the vaccine adjuvant is toxic,
there is a limited number of cases and deaths compared to other diseases,

are attacks.

These statements can be produced by either a single author or by several. Their strength is partly dependent on the context and on personal evaluations. Finally, the statement:

(1-1c) The initial vaccine adjuvant has been replaced by a much more neutral one that has no effect on humans,

is an attack of (1-1b); it cancels out the attack to the claim produced by the initial statement.

Beside the support and attack relations presented above, propositions may also attack the inference that connects two arguments:

(1-1d) Ebola is dangerous with high contamination risks, therefore vaccination is necessary,

is attacked by:

(1-1e) Recent epidemiological investigations show that vaccination does not stop disease dissemination.

Supports and attacks are crucial components of argumentation, which is based on the recognition of a difference of opinion between parties: these parties express doubts about the other party's standpoint. A preliminary step is to identify differences of opinion and then the basis on which they can be resolved. Doubts may bear on a unique or on multiple ones, for example when the claim is complex or has multiple facets. In the above example (1-1b), the adjuvant is toxic attacks a facet of the vaccine, i.e. how it is diluted before injection. Other facets include specifically its costs and the way it has been tested on populations. Analyzing the structure of arguments and then evaluating them is the ultimate goal of argumentation. Argumentation is a complex discourse activity that must not be confused with a demonstration. Argumentation aims at convincing someone of a certain point of view, or at resolving conflicts. Argumentation relies on more shallow structures that in formal demonstration such as argument schemes, associated with norms, rules and constraints for which models are being defined.

An argumentation can be realized in a number of manners. For example, it can be a monologue, where propositions for and against a claim are developed, for example in a news editorial. In that case, the author attempts to present an overall picture of the different positions for or against that claim. He may also wish to anticipate attacks by readers. An argumentation can also occur in a dialog between two or more persons that express different points of view concerning a claim or a standpoint. This is, for example, the case of TV or online debates, deliberation and litigation situations.

Argumentation can therefore be oral or based on written elements produced using various types of media. Argumentation is mainly aimed at (1) convincing someone or a group of people of a certain point of view or (2) coming to a reasonable agreement between two or more parties about a disagreement (e.g. in mediation and deliberations).

When one argues for a given standpoint, he is the proponent of that standpoint. The actors that disagree and argue against it are called the opponents. Arguing is not demonstrating: a proponent presents good reasons to support a claim, he does not logically demonstrate that the claim is true. He simply gives good reasons that justify the claim. A demonstration, on the contrary, is based on facts, inference rules and axioms described in a formal language, whereas argumentation expresses facts and causal schemes in natural language. It follows the well-known statement uttered by a judge: I need proofs, not arguments!

It must be noted at this stage that argumentation is often contrasted with explanation. When one explains something to a listener, the aim is to bring new knowledge to that listener or to help him to modify his beliefs. This knowledge is hypothesized to be true and non-controversial, unless otherwise stated. An argumentation does not a priori bring any new knowledge to the listener: it is aimed at persuading him of the validity of a certain claim. However, in an argumentative discussion, it is frequent to have a combination of arguments and explanation. The difference between these two notions in a discourse is not easy to make: it depends on the knowledge and beliefs of the speaker and the listener.

According to several authors, an opinion is also a slightly different notion: it is a statement that is not supported by a justification. Arguments are necessarily supported by one or more justifications even if some of them are implicit. Such implicit justifications are called enthymemes.

1.2. Argumentation and argument mining

Argument mining is an emerging research area that introduces new challenges both in natural language processing (NLP) and in artificial intelligence (AI). Argument mining is a very challenging area that involves...