contributed articles
doi:10.1145/ 2500891

Improve online public discourseby connecting opinions across blogs,
editorials, and social media.
By Floris Bex, John Lawrence,Mark Snaith, and Chris Reed

Implementing
the Argument
Web
Argument and debate are cornerstones of civilizedsociety and intellectual life. As online activity usurps
many traditional forms of communication, we would
hope to see these processes alive and well on the Web aswell. But we do not. Too many mechanisms for online
interaction hamper and discourage debate, facilitatingpoor-quality argument and fuzzy thinking. Needed
are new tools, systems, and standards engineered into
the heart of the Web to encourage debate, facilitate
good argument, and promote a new online critical
literacy. This is the Argument Web vision, involving a
Web platform combining linked argument data with
software tools that make online debate intuitive for its
participants, including mediators, students, academics,
broadcasters, and bloggers.
New opinions are constantly being presented on
websites, blogs, news sites, and discussion forums,
challenged and evaluated by a diverse worldwide usergroup. An important problem is the semantic
66

communicatio ns o f th e acm| octo ber 201 3 | vo l . 5 6 | no. 1 0

structure of argumentative viewpoints;
for example, whether one person
agrees with another or whether a particular statement conflicts with a claim
is not captured. A further problem isthere is no representation of how arguments across the Web relate to one
another and contribute to the overall
picture. Despite the numerous vocal
communities on the Web, they remain
relatively isolated because opinions
are not connected.
Needed is an infrastructure allowing for interconnected arguments to beposted anywhere on the Web througha comprehensive underlying ontology of argument. This is the Argument
Web,13,14 a URI-addressable structureof linked argument data making it
possible to follow a line of argument(on a particular topic or by a particular person) across disparate forums,
comments, editorials, and multimedia resources. A number of bespoke
tools have been developed as part of
the Argument Web implementation.
Various annotation and analysis tools
have been developed for academics
and trained discourse analysts. Moreover, while argument analysis may be
a specialized skill, most people conduct an argument, give reasons, conclude, and give grounds for disagreement every day; it is this intuitive skill
the Argument Web aims to support
explicitly. Familiar interfaces (such as

key insights
 T he Web’s focus on popularity (suchas reflected through “like” buttons
and number of followers) instead of
rationality (such as through “agree” or“disagree” buttons and number of people
subscribing to an opinion) discourages
online discourse.

 T he Web’s numerous vocal communities(such as bloggers, Reddit, and Twitter)are rather isolated, with opinions
expressed on one website not directly
connected to opinions expressed onother websites.

 T he Argument Web includes new tools,
systems, and standards for linking
argument data, allowing opinions to
be connected across the Web throughsemantically meaningful links.

Illustration by Ca rsten Reisinger

blogging and instant messaging) havebeen adapted, allowing users to navigate opinions and express agreement
or disagreement.
In 2007, some of the basic ideas behind the Argument Web were first expressed by Rahwan et al.14 This article
and corresponding webpage (http://
www.argumentinterchange.org)
explore the first full prototype, discussing a mature version of the argument
ontology, implementation of the underlying linked infrastructure, andtools allowing interaction with the Argument Web.
Connecting Opinions
One of the main functions of the Web

is enabling people to share, comment
on, and argue on a variety of topics,
from the newest video game to whoshould be the next president. Popular blogs can have large numbers offollowers who comment on the blog
and on each other; discussion forums(such as Reddit) allowing people toshare and discuss topics and incorporate mechanisms for rating contributions and users; and Twitter andFacebook allowing users to quickly
share and comment on their friends’
opinions. While online interaction isfacilitated and promoted, online critical discussion usually is not. Comments are rated almost solely according to popularity, not according towhether they present a valid rational
argument; a funny picture of President Barack Obama is more likely to
end up on the front page of a website than a cogent argument for why
one should vote for or against him. It
may be possible to “like” a comment,but one cannot “agree” or “disagree”
with a comment. Moreover, the only
type of relation between two statements is usually “reply” (statement 1
replies to statement 2) and more specific argumentative relations (such as
statement 1 supports statement 2 andstatement 1 opposes statement 2) are
not available.
The need for better online argument and debate is recognized byoctob er 2 0 1 3 | vo l. 56 | n o. 1 0 | c om m u n icat ion s of t he ac m

67

contributed articles
websites supporting online critical thinking and structured debate.
Some offer databases of structured argument for users to explore. Debatabasea (formerly Debatepedia) offers numerous high-quality debates
about a range of topics, including
those for and against a particular
topic. Archelogosb concentrates onarguments from ancient philosophy(such as Aristotle and Plato), making
explicit their argumentative structure

and logical interconnections. Other
websites are more interactive, allowing users to construct arguments ina structured way. Truthmappingc isa more interactive discussion boardthat introduces slightly more structure to a debate, requiring new statements either support or oppose an
existing statement. In Debategraph,ddebates are visualized as radial trees,with a central topic node surroundedby related statement nodes. Usersa http://idebate.org/debatabaseb http://archelogos.com

c http://truthmapping.com
d http://debategraph.org

Figure 1. Example of linked argument data.

“Should we
invade Syria?”

SupportSupport

1. “Assad should beheld accountable”
Press conference

Support

2. “Syria is not Iraq”
Newspaper column

Conflict

3. “Invasion is
militarily feasible”
Magazine article

4. “The West invades
so it can claim themoral high ground”
Radio program

Conflict
Conflict

5. “Columnist
is a leftie”

6. “McCain is
not a leftie”

Forum

Figure 2. The Argument Web architecture.

Argument Web applications

JSON

JSON

Argument Web middle layer API

Argument Web social layer API

dialoguecontrolAML

query
management

DOT

LKIF

participant
management

JSON

user
management

OAuth

RDF/OWL

RTNL

SVG

AIF Web service interface

AIFDB

AIFDB

server platform

68

communicatio ns o f th e acm

AIFDB

Adjunct
AIFDB Ontology

server platform

server platform| octo ber 201 3 | vo l . 5 6 | no. 1 0

click nodes to expand elements of adebate and connect new nodes to thetree via relations (such as respond,
support, and oppose). A graphical presentation like the one in Debategraphcan give a quick overview of complex
debates,e helping users make sense11
of a large amount of information;other examples of websites offeringvisual representations of arguments
are Argunetf and Cohere.
These Web technologies all havean explicit semantic structure thatconnects the statements and arguments in a debate, allowing for far
better navigation and analysis of adebate; for example, we can render
the structure as a graph or as an outline report, count the number of arguments for and against a claim andthus evaluate argument strength, analyze the graph and identify circularreasoning or gaps in chains of arguments, and discover inconsistencies
among arguments and agreements
among disputants.
The main limitation of these websites is there is little or no integration
between them and they do not fully
connect to the Web as a whole. Links tosources on the Web can be incorporated into arguments, and debates can beshared by providing links to separate
discussion threads or debate graphs.
However, these links contain no explicit semantics. Hence, each site provides
a silo of structured and semanticallyrich argumentative content, but thesesilos are not connected to one anotheror to the rest of the Web, at least not
through semantic links.
To illustrate the added value of connected arguments across the Web,
consider the issue of Bashar al-Assad’s
Syria and the morality of potential
Western intervention in the summerof 2012. Say you ask, “Should we invade
Syria?” Ideally, you would find a number of arguments, along with links totheir sources:
Video. A YouTube video of a press
conference in which the U.K. Primee For examples of argument and debate analyses, see the “Can Computers Think” argument
at http://www.macrovu.com/CCTGeneralInfo.
html and http://debategraph.org/can_computers_think and the U.K. nuclear weapons
debate at http://www.florisbex.com/NuclearArgMap.pdf
f http://argunet.org

contributed articles
Minister says Assad should be held accountable for war crimes;gNewspaper. A column in the online
edition of The Guardian claiming Syria
is different from Iraq;hMagazine. An article in Foreign Policy
exploring the military feasibility of attacking Assad’s Syria;i andRadio. A point about the moralityof intervening put forward in the BBC
Moral Maze program;j(You focus on the newspaper column, which links to other arguments
posted on the Web agreeing or disagreeing with the fact that Syria is different from Iraq.)
Forum. One counterargument posted on a forumk says the writer of thecolumn is a “leftie” with no idea what isthe difference between Syria and Iraq
or what real war means; andOn the same forum, another user
disagrees with this argument, saying“Arizona Senator John McCain is for intervention and is no leftie.”
Figure 1 outlines the small Web oflinked arguments, along with support
and conflict links. Note the statements
and arguments can be on different
webpages, but a counterargument canalso be given on the same page, as in
the forum. In order to realize linked
arguments across the Web we needto conform to the demands of linked
data,4 in that each piece of data, or thenodes and links between them, is addressable through a unique URI thatstands in well-defined relationships toother URI-addressable data. Only two
projects—Coherel,7 and the Argument
Web—allow for linked argument data.
Cohere aims to link ideas on theWeb. Individual online statements canbe referred to through a URL, supporting a range of semantic relationships
between components (such as “explains” or any other relation the user
wants to define). While this breadthis helpful for Cohere, it makes it diffig http://youtube.com/watch?v=OBPcv7qSIi4
h http://guardian.co.uk/commentisfree/2012/
feb/10/syria-not-iraq-wrong-intervenei http://foreignpolicy.com/articles/2012/01/10/
the_syrian_invasionj http://bbc.co.uk/programmes/
b01kkp5q#synopsis
k http://amazon.com/forum/politics?_encodin
g=UTF8&cdForum=Fx1S3QSZRUL93V8&cdThread=TxIAO1K6FZP0SI
l http://cohere.open.ac.uk

It is possible to use
the Argument Web
to explore, say,mathematicalaspects ofarguments
phrased innatural language
from various
sources on the Web.

cult to build tools with specific applications; for example, argumentation
requires a fixed set of argumentative
relationships that can then support
computational processing (such as
visualization, navigation, and evaluation) not easily supported if the relationships being captured are dynamic.
Infrastructure of the Argument Web
The Argument Web aims to create a
Web infrastructure that allows forstorage and automatic retrieval andanalysis of linked argument data.4
It is based on a common ontology
for argument called the Argument
Interchange Format6 (AIF) that ties
together natural linguistic models
of argument (such as models that
see argumentation as a language activity17) with abstract mathematicalmodels of argument.2,9 It is possible
to use the Argument Web to explore,
say, mathematical aspects of arguments phrased in natural language
from various sources on the Web.
AIF Ontology. At its core, the AIF
ontology distinguishes between information (such as propositions andsentences, or the nodes in Figure 1)
and general patterns of reasoning that,applied to specific information, provide the individual relations between
information (the links in Figure 1).
Links can be classified according to thescheme they fulfill.13 The AIF schemetaxonomy is based on argumentation
schemes18 that are generally accepted
for scholarly investigation of argument; for example, the counterargument in Figure 1 saying the columnist
is a “leftie” is a typical ad hominem
argument,17 an argument against a person. Here, it is not what the columnist
says—Syria is different from Iraq—that
is being countered but the credibilityof the speaker; that is, people who are
left-of-center politically should not betaken seriously when commenting on
invading other countries.
In addition to argument structures,or static structures representing information and the support and attack
links between them, as in Figure 1,
the AIF ontology is also able to capture the argument processes, or the
dynamic discussions in which people
put forward and challenge claims andreasons. In recent work we showed
the AIF ontology can be used as aoctob er 2 0 1 3 | vo l. 56 | n o. 1 0 | c om m u n icat ion s of t he ac m

69

contributed articles
general framework for capturing dialogue protocols.3 Such protocols provide rules that determine which typesof responses can be given to whichtypes of statements or questions; forexample, a challenge statement like
“Why is invading Syria militarily feasible?” can force other parties to givereasons for their claim, as in, “Weshould invade Syria because it is militarily feasible.”
Note there is no restriction on thecontent of an argument; for example,
argument contents may themselves be
expressed in a common formal ontology, meaning they yield to additional
computational processing. On the other hand, this increases the complexityof the ontology, meaning common understanding of the ontology is reduced,
and potential users are largely restricted to scholars and experts. Hence, theAIF core ontology is kept as basic as
possible, and the Argument Web does
not demand explicit semantic characterization of argument content.
Semantic Web. The Argument Web
essentially represents a large-scale deployment of Semantic Web1,13 technology, taking a pragmatic approach toissues of infrastructure by specifying
the ontology not only in the formal languages of the Semantic Web (such as
the Web Ontology Language, or OWLDL) but as an instance of a relational
database schema adumbrated by a setof Web services acting as an RDBMS forinteracting with the data as if it werean RDF triple store. This approachbuilds on highly scalable, mature,robust, commercially accepted database systems while still conforming to
the main principles and demands oflinked data.4
Argument Web resources are distributed across multiple databases,
instances of what are called AIFdb (adatabase solution for the Argument
Web10) in reference to the underlying
AIF ontology (see Figure 2). Each AIFDB
instance provides interfaces through avariety of formats for programmatic access, Semantic Web processing, visualization, and compatibility with existingargumentation tools.11 Core argumentation functionality is then provided
by the Argument Web Middle Layer inthree areas:
Query management. Allowing developers to query, say, what argument(s)70communicatio ns o f th e acm

Even rhetoricallyand linguisticallysophisticatedmaneuvers(such asad hominem
argumentation)
can be captured in
the Argument Web.

| octo ber 201 3 | vo l . 5 6 | no. 1 0

supports a given claim or whether a given position conflicts with any other(s);Participant management. Allowing
developers to query, say, which users
have put forward a given argument;
andDialogue control. Allowing developers to execute dialogue protocols and,in that context, query whose turn it
is in a given dialogue and what legal
moves are available to the participants. The Argument Web social layer
provides developers a straightforward
library through which to construct applications that interact with the Argument Web.
Because the Argument Web, like the
Web itself, is designed for public use,the data being produced is noisy, thus
presenting a challenge when trying tobuild computational systems able toreason over Argument Web resources.
One approach to dealing with noisy
data is engineering oriented: Design
the reasoning systems in the full expectation the data over which they work isnoisy, and therefore results are either
only as good as the data from which
they are drawn or else drawn from subsets preprocessed to reduce noise.
The Argument Web’s core concept—argumentation—also provides
another approach to dealing with noisy
data. Take claim identity. In any large
distributed knowledge base updated
by many different individuals, a major
challenge is how to identify when two
items in the knowledge base are thesame. However, the claim that, say,“the domineering Western aggressors
invading Syria” is the same as “Western liberating forces intervening in
Syria” is precisely the sort of claim thatis liable to be the source of a dispute.
Thus, what seems to be an engineering
challenge—identifying duplicates—
becomes a subject of discussion on the
Argument Web.
Argumentation Tools
and Interfaces
A number of tools have been developed as part of the Argument Web
implementation. Some (such as forargument visualization and analysis)
are geared mostly toward educational
uses. However, in order to open up
the Argument Web to a broader audience, familiar interfaces (such as
blogging and instant messaging) cancontributed articles
be adapted to support argumentation.8 Moreover, the solid theoreticaland infrastructural basis of the Argument Web allows us to experimentwith new technologies for discourse
and argument analysis, or Argument
Web app library,m discussed in thefollowing sections.
Argument visualization and analysis.
As noted, Web technologies for argumentation focus in part on visualizing arguments as graphs or diagrams
easily navigated by users. The idea of
online argument visualization stems
from offline argument-diagramming
tools used in, say, courses on criticalthinking and for teaching complex legal argumentation.12 The Argument
Web implementation recognizes existing approaches to argument visualization by defining and implementing
import-export functions2,8 for existingargument visualization tools.n
Using a visual interface to AIFDB(see Figure 3a) lets users view andnavigate the Argument Web; like Debategraph, nodes can be clicked to
expand new parts of a debate. New arguments can be constructed using theOnline Visualization of Argument, or
OVA, allowing direct analysis of Web
content; text from a website can beselected and input directly to an argument graph that is then saved to the
Argument Web.
For the University of Dundee’s partnership with the BBC, we wanted toanalyze a discussion in real time. The
BBC’s Radio 4 program “The Moral
Maze” broadcasts 45 minutes of debate
on a moral issue each week. The idea is
if an analysis is done in real time andsaved directly to the Argument Web,
listeners would be able to interact withthe discussion as it happens. However,a trained analyst can take weeks to analyze even one hour of debate, so analysis must be performed in parallel. We
therefore designed and built a collaborative workspace—the AnalysisWall,a touchscreen measuring 11 feet by
7 feet running bespoke analysis software14 (see Figure 3b). As the program
was broadcast live, stenographers provided a text feed, segmentation analysts broke the text into its component
parts, and eight analysts collaborated

Figure 3. Argument visualization and analysis.

(a)

(b)

Figure 4. The Arvina 2 debate interface.

m http://www.argumentinterchange.org/libraryn http://argumentinterchange.org/developers
octob er 2 0 1 3 | vo l. 56 | n o. 1 0 | c om m u n icat ion s of t he ac m71

contributed articles
to tease apart the structure of what isbeing said, directly inserting it into the
Argument Web.
Direct discussion and mixed-initiative argumentation. Direct discussion between two or more people on
the Web takes place not just via email
and instant messaging but also on forums and message boards. However,these technologies offer only themost basic of structural tools, and theinferential structure of an argument
in a discussion is easily lost. The Webbased discussion software Arvina10(see Figure 4) allows participants todebate a range of topics in real timein a way that is structured but at thesame time is unobtrusive. Users
can ask questions (such as “Do you
agree?” and “Why do you think thisis the case?”) of other participantsin the discussion, as well as express
their own agreement or disagreementwith a particular point and provide
supporting reasons for their views.
Moreover, Arvina can use dialogue
protocols to structure the discussion
between participants.
Arvina can take on a multi-agent
system populated by agents representing authors whose opinions areavailable on the Argument Web. It isthus possible to question the participants of, say, past Moral Maze radio
programs about their opinions, andagents representing participants canbe added to a discussion and questioned about what they think about
the topic discussed during the program. An agent then answers by giving the opinions originally expressed
during the broadcast by a particularparticipant. In this way people are able
to question any opinion expressed on
the Argument Web, whether originallyadded through OVA, ArguBlogging, orother tools.
Argument blogging. A final exampleof how argumentation technologies
based on the Argument Web facilitates
online debate concerns blogging, ahighly popular form of online communication. If one wants to reply to an
opinion presented somewhere on the
Web in a blog, the usual way is to provide a simple hyperlink to the article orpage in which the opinion is expressed.
However, the resulting structure of
supporting and competing opinions
is easily lost due to lack of semantic information in the links.
We built a simple tool called ArguBlogging, for Argument Blogging,10
to improve rational debate throughthis popular form of expressing opinions online. It ensures that, if desired,opinions on blogs and other webpages
can be linked through the underlying
infrastructure of the Argument Web,
allowing users to agree or disagreewith opinions anywhere on the Web,simultaneously posting it to their blog
(connecting to two popular blogging
platforms, Blogger and Tumblr) andadding it to the Argument Web; Figure
5 is the ArguBlogging window (or widget) rendered on a webpage, providing
options for responding.
A typical blog post through ArguBlogging contains an “argue” button that, clicked, brings the widget
onscreen. It allows users to respondto the blog post as a whole throughArguBlogging and is similar to the

Figure 5. The ArguBlogging widget.

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comm unicatio ns o f th e acm| octo ber 201 3 | vo l . 5 6 | no. 1 0“like” button on Facebook and “share”
button on Twitter.” This way, the ArguBlogging tool uses familiar interaction styles to enable critical argumentation on the Web.
Evaluating the Argument Web
The kind of continuous evaluationneeded by the Argument Web involves
usability in two distinct domains—
public and academic—and expressivity
and computational flexibility throughmetrics drawing on formal, computational methods, as well as on more
pragmatic engineering principles.
In terms of raw usage through compatible tools (such as Rationale andAraucaria), the Argument Web today
includes tens of thousands of users
worldwide. The native applications(such as OVA) released in the past few
years naturally involve fewer, but thecore AIFdb includes more than 11,000
argument components, the second
largest semantically rich argumentation dataset (after Debategraph),
including in seven languages; forexample, the Archelogos repository
is fully imported into the Argument
Web. More significant, the infrastructure and analysis tools have been usedin at least seven research projects involving 10 labs in France, Poland, theU.K., and the U.S., each with different
foci, including generative and analytical, multilingual and monolingual,and dialogical and monological.
In terms of expressivity, the Argument Web balances well-definedformal properties and pragmatic solutions to engineering problems; forexample, the underlying ontology isdemonstrably more expressive than
one of the foremost formal accountsof defeasible argumentation, ASPIC+,2but a well-defined subset can be used
to induce abstract frameworks onwhich evaluation can be performed.16
Ongoing work in discourse analysis5demonstrates that even rhetoricallyand linguistically sophisticated maneuvers (such as ad hominem argumentation) can be captured in the
Argument Web. At the same time,
formal description-logic analysis of
the AIF ontology13 shows powerful
abstractions can support advanced
search and evaluation of arguments
involving, say, specific schemes of presumptive reasoning.

contributed articles
The Argument Web’s ultimate objective is to improve the quality of online argument and debate. Keeping in
mind that evaluation of natural argument is philosophically thorny, it ispossible to propose objective metrics
through which to assess natural arguments, including, say, consensus
about which arguments are best (onemight disagree with an argument
while still appreciating its merits);
exhaustiveness, speed, volume of content, signal to noise, and structuralcomplexity; argument richness (interms of the range of argument typesused); and dialogue richness (range of
dialogical moves used).

Debate is a good
way to navigate
and support
engagementwith complex
issues involving
disagreement (suchas abortion, climatechange, and military
Conclusion
The Argument Web represents the intervention)
first technology linking debate, dis- that are not justagreement, and argument structuresfrom a variety of tools applied in dif- important but thatferent domains. The approach has
define our time.
strong potential both academicallyand practically. Along with developer
and user interest and increasing Argument Web resources, the academic
community gains access to a valuable
resource that, particularly for computer scientists, can function as a testbed for new theories of argument-acceptability applications and as a richdataset with which to deploy new applications; for linguists and philosophers, it offers a unique corpus of discourse activity, replete with detailed
annotation and commentary.
By solving theoretical problems involving how argument structures canbe navigated and extended throughdialogical processes, the Argument
Web opens up a new class of application in which intuitive, dialogically
based interfaces (such as Arvina and
ArguBlogging) can be used to explore
and improve large-scale debates. Thereis evidence19 that debate is a good way
to navigate and support engagementwith complex issues involving disagreement (such as abortion, climatechange, and military intervention) thatare not just important but that define
our time. By supporting and facilitating engagement in debates (otherwise
daunting, leading even to disengagement and disempowerment) the Argument Web promises to play not only atechnological but an important societal role as well.

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Floris Bex (f.j.bex@rug.nl) is a researcher andinstructor at the University of Groningen, Groningen, The
Netherlands.
John Lawrence (johnlawrence@computing.dundee.
ac.uk) is a Ph.D. student at the School of Computing of the
University of Dundee, Dundee, U.K.
Mark Snaith (marksnaith@computing.dundee.ac.uk)
is a postdoctoral research assistant at the School ofComputing of the University of Dundee, Dundee, U.K.
Chris Reed (c.a.reed@dundee.ac.uk) is a professor at the
School of Computing, University of Dundee, Dundee, UK.

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