This guest post is by Joseph O’Mahoney, currently a Stanton Fellow at MIT and an Assistant Professor in Seton Hall’s School of Diplomacy and International Relations.

In the US, support for President Donald Trump’s executive order, which restricts travel to the US by citizens of seven Muslim majority countries, has been mixed. Perhaps surprisingly, the Islamic State or ISIS is wildly in favor of the so-called “Muslim ban.”. Postings to pro-ISIS social media accounts called the proposed order a “blessed ban” and hailed Trump as “the best caller to Islam”. Why? Because it “clearly revealed the truth and harsh reality behind the American government’s hatred toward Muslims”. General Michael Hayden, former Director of the NSA and CIA, is worried that the ban makes the claim that “there is undying enmity between Islam and the West” more believable to “Muslims out there who are not part of the jihadist movement”. By contrast, a visibly compassionate and welcoming response to Syrian refugees by Western countries “has been incredibly damaging to this jihadist narrative”.

This is just one example of international politics consisting of competing arguments, with different actors making claims, marshaling evidence, and trying to win over various audiences. This pervasive feature of international relations has been the subject of a research program since at least Risse 2000, with work including Schimmelfennig 2001, Crawford 2002, Mueller 2004, Krebs and Jackson 2007, Deitelhoff 2009, Bjola and Kornprobst 2011, and Seymour 2014. However, this literature has so far underplayed a couple of important points. For example, some have seen arguments as persuading people to change their mind on the basis of the logical beauty of the argument itself, ignoring the actual way that people evaluate and respond to arguments. Also, there has been too strict a division between rhetoric and action, and between signaling facts and interpreting the normative status of those facts.

In a paper coming out in International Organization, I present a way of understanding how arguments have effects with reference to a model of decision making called “reason-based choice”. When we are choosing or deciding we have competing reasons for and against options; “pro and con” lists. This process is so fundamental that some cognitive scientists have a theory that human reasoning evolved in order that humans could argue with each other by presenting and defeating reasons for action (perhaps so that we can coordinate on collective projects). This could explain why people fail those tests of rationality set up by Kahneman and Tversky – human thought is aimed not primarily at truth but at evaluating arguments. I argue that we should incorporate this idea into our theories of argumentation in international politics and see a key role of arguments as providing, supporting, or undercutting reasons for or against a particular action, not as changing utility functions or people’s strongly-held beliefs. So, when ISIS is trying to recruit by arguing that “The West hates Muslims”, they are trying to create a reason to join them, i.e. because an embattled Islam needs defenders. They are not trying to convert an average American or European to true belief in a Caliphate, nor trying to reach a reasoned consensus.

The paper then describes a schema in which actors try to make their arguments more convincing by manipulating what evidence the audience sees as being in favor of their preferred conclusion. This is especially important when dealing with essentially contested concepts (like democracy, terrorism, aggression, or “a threat to national security”) where there is no agreement over what evidence would be in support. In particular, actors can take action to change the facts so that their claims seem more real. This process I term rhetorical adduction (to adduce is to put something forward as evidence). Rhetorical adduction is a widespread phenomenon in international politics. An intuitive example I use in the paper concerns factions in a university department arguing over hiring. One faction wants to hire an inside candidate, but the opposition provides a reason against this choice; an inside candidate would constitute nepotism! So, the first faction argues that if a standard search were run, the outcome of that search would not be nepotism. They run the search, perhaps tailor the job ad to be relatively specific, then select the inside candidate. The charge of nepotism, the reason against hiring them, has been made less convincing. In the ISIS example, it seems plausible that the terror attacks in Paris in 2015 were aimed at provoking attacks on ISIS and thus “reinforcing the notion that the Islamic world is under siege and needs to be defended”. ISIS was arguing that they were under attack, and then took action, killing French civilians, to try and make their argument appear more true to the people they were trying to recruit. Analyses of international politics that ignore the role played by rhetorical adduction, that is, attempts by actors to change the world so that their argument seems more convincing to their audience, will end up supporting policy that works counter to their aims. Trump’s Muslim ban, by providing fuel for ISIS’s arguments, is a tragic example. That is, unless the ban is itself actually strategically aimed at supporting Trump’s argument to the US electorate that he is “taking action” and “keeping us safe”.