Does Having More Competing Groups Imply More Political Violence?

According to the theory of outbidding, violent non-state actors have incentive to “advertise” their “services” through violence to capture a larger share of their audience’s support and resources. A natural conclusion drawn from this is that violence increases as the number of groups increases; the greater competition forces these groups to work harder to gain traction in their communities.

While this literature is large and growing, empirical support for a connection between violence and the number of competing groups is mixed. Some large-n studies find that violence positively correlates with the number of groups. Some don’t. What explains this discrepancy?

In a new working paper, I argue that a countervailing deterrence effect helps make sense of the mixed results. At present, outbidding theory only focuses on the competition between groups; it ignores the actions of the target of the violence. Nevertheless, the demands that a target imposes on an affected population influence recruitment rates, and groups have greater incentive to invest in competition when there is a larger pool of money to compete for. Thus, if a target observes a large number of groups and fears that competition will lead to massive violence, it may wish to withdraw from the problem area. This quashes the supply of recruits and reduces competition. In turn, a large number of groups can have a deterrent effect and possibly lead to less violence.

However, it is unclear whether the deterrent effect or the competition effect predominates, so I model the interaction to look for answers. As it turns out, whether more groups implies more violence depends on a seemingly irrelevant characteristic: the function that maps encroachments from the target to civilian support for resistance groups.

Naturally, this function should be increasing. That is, the more the target reduces civil liberties, captures additional territory, or expands its military into foreign lands, the more the effected population would want to support organized resistance. But the rate at which it increases could vary from case to case. Do the initial encroachments lead to a sharp increases in volunteer rates that slowly taper off? Then the function is concave, like the red line in the figure below. Or do initial encroachments lead to marginal increases at first but larger increases at later demands? Then the function is convex, like the black line in the figure.

concavity

Surprisingly, the anticipated relationship between violence and the number of groups only holds when the function is convex (black line). The intuition is exactly as the current literature understands outbidding, so I will not explain it any further.

The anticipated effect disappears when the function is concave (red line), though. The explanation is a bit more involved but makes perfect sense in retrospect. Imagine for the moment that the target state wanted to capture a small portion of the good under these concave conditions. This is going to spark a sharp marginal increase in the amount of violence it faces. Thus, if it is worth taking the first bit (and suffering a lot of violence), it is worth taking the entire policy under dispute (and suffering only marginally more violence as a result).

So when the function is concave, the target’s optimization problem is a simple binary choice between taking nothing and taking everything. But recall that violence is increasing in the number of groups. Consequently, with more groups, taking the whole lot looks less attractive. In turn, when the number of groups is low enough, the target takes everything; when that number is high enough, it takes nothing.

Observed violence as a function of the number of competing organizations. The red dots track violence when the function is concave, with black for convex.

Observed violence as a function of the number of competing organizations. The red dots track violence when the function is concave, with black for convex.

As the above figure illustrates, this leads to a nonmonotonic relationship between the number of groups and violence. Below that critical number of groups, violence increases as the number of groups increases. This is because the target is still taking the entire policy under dispute and the additional competition is producing increasingly more violence. But after that critical number, violence drops off because there is no civilian support for the groups to compete for.

The remainder of the paper discusses the empirical implications of the model. The key takeaway here is that we need some way to measure these supply curves to obtain useful large-n estimates of the effect of the number of groups. There is no simple fix here, though foreign interventions are seemingly more likely to fit the concave (red) case.

Again, the paper is here. If you have any comments, please send me an email!

Abstract. The theory of outbidding states that terrorist, insurgent, and rebel groups use violence to capture a greater share of their audience’s resources. I argue that opponents of these groups should endogenously anticipate this dynamic, which potentially alters their aims. Although a seemingly obvious implication of outbidding is that violence increases as the number of groups (and thus competition) increases, I show that this may or may not hold once we factor in the opponent’s decision. This is because the target states—fearing group competition—might endogenously reduce their demands. The results help explain empirical inconsistencies regarding outbidding. Using comparative statics from the model, I then discuss the challenges to making valid inferences regarding outbidding.

The Power Shift Myth: Understanding Preventive War

Shifting power is often cited as an explanation for war. But the causal mechanism isn’t so straightforward.

While the concept of preventive war dates back to Thucydides’ and The History of the Peloponnesian War, the modern understanding is just barely in its third decade. In Rationalist Explanations for War, James Fearon conclusively shows that bargained settlements exist that leave both parties better off than had they fought. The puzzle of war is why wars occur despite this inefficiency.

One of Fearon’s answers is that power may shift over time. Although a rising state and a declining state may reach an efficient bargain in the future, the declining state may be better off securing a costly but advantageous outcome through war today. As much as the rising state might protest, it cannot credibly commit to maintaining the status quo distribution of benefits. Rather, it will eventually want to exploit its new found power by shifting the benefits in its favor.

This idea has taken off in international relations literature. It is now the textbook explanation of preventive war. (See Frieden, Lake, and Schultz, Kydd, or myself.) It also has obvious empirical implications—growing power implies more war—which many quantitative scholars have explored. (See Bell and Johnson, Schub, and Fuhrmann and Kreps for recent examples.) The literature is growing, and knowledge is accumulating. These are great things to see.

A Hidden Assumption
Unfortunately, the causal mechanism behind preventive war isn’t entirely clear, and the notion that power shifts alone cause war is a bit of a myth. One hidden assumption in the simple preventive war construction is that power growth is exogenous. That is, the rising state does not choose whether to grow or how. It simply does, as though power grows on trees.

Yet, in practice, most power shifts are endogenous. Raising an army, building new aircraft carriers, investing in missile defense, and designing nuclear weapons all require active decisions by the state. The basic model ignores this part of the process and instead jumps to the strategic tradeoffs once the state has decided how to shift power.

Thus, a natural question to ask is how endogenous power shifts impact the probability of war. Thomas Chadefaux addresses this in his aptly-titled Bargaining over Power article. Perhaps surprisingly, the war result reverses completely—in any instance that a preventive war would have been fought, bargaining over power leads to a peaceful outcome.

The intuition is straightforward once you work through the mathematical logic. A rising state really wants to avoid war today because fighting would take place on terms most disadvantageous to it. Thus, if it had to choose between undertaking a power shift that would induce preventive war and a smaller power shift that the declining state would acquiesce to, it would choose the latter. After all, a smaller (but realized) power shift is preferable to a costly war.

The New Puzzle
Of course, Chadefaux’s results only take us further down the rabbit hole. There is ample historical evidence to tell us that states fight wars to forestall shifts in power. What then actually causes preventive war?

The literature provides a variety of answers, which I will now attempt to synthesize. First, some power shifts may actually be exogenous. If demographic trends are at the root of a power shift, countries may be unable to effectively limit their future power. In civil conflicts, protesters may be unable resolve coordination problems in the near future, leading to dramatic shifts in power over a short period of time. This helps explain why autocratic regimes exert such great effort in controlling their citizens’ movements.

Fearon recognized that the commitment problem disappears when states can bargain over power. But when the object of value also confers military advantages, bargaining can break down when there are indivisibilities in the good. Chadefaux also showed that having distinct discount factors can lead to conflict even without those indivisibilities.

Implementing such an agreement may create other bargaining problems, too. Debs and Monteiro investigate a model with costly power shifts that declining states cannot effectively monitor. Declining states sometimes need to initiate wars so as to deter weapons construction they might not otherwise observe. My research looks to see whether offering concessions-for-weapons can resolve these issues. Fortunately, the answer is yes. However, in the book manuscript I am working on, such deals fail when there is uncertainty over the declining state’s willingness to intervene.

Undoubtedly, there are many more answers to why states fight preventive wars even when power shifts are endogenous. Sadly, though, this literature feels somewhat stifled given that new research often constructs models with exogenous power shifts without any justification for why states cannot negotiate over power.

Empirical Implications
I conclude by discussing some implications of endogenous power shifts. First, quantitative scholars should care greatly about bargaining over power. Although we have established connections between power shifts and war, the above theory indicates that the causal relationship is not obvious. For example, it might be that other bargaining problems cause to both power shifts and war. We need to think carefully about these higher-order issues and search for empirical evidence of them.

Policy-wise, this tells us a great deal about negotiations with Iran. If Tehran constructs a nuclear weapon, it must be doing so because it does not anticipate preventive war. Thus, one way the United States can hold Iran to its commitments under the Joint Comprehensive Plan of Action is to maintain a credible threat to fight a war should Tehran violate the agreement. Internalizing the threat, Iran would not build a weapon. This is perhaps the ideal for Washington—the American threat to invade does all the heavy lifting, allowing the United States to obtain its best policy outcome without actually paying the costs of war.

rationcover

Some Thoughts on The Force Awakens (Spoilers)

Massive spoilers below…

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1) I suspect some viewers might roll their eyes at the fact that the galaxy is still in the middle of a civil war, but this is somewhat realistic. Civil wars tend to last a loooong time. The civil war in Afghanistan, for example, has been going on since 1978. One could argue that Korea has been in civil war for the last 65 years. (The Force Awakens makes it seem like both the Republic and First Order control and govern territory, like North and South Korea.) The good news, if there is any, is that political scientists have a pretty good idea why civil wars take forever to end.

2) What a strange world we live in where James Bond has more screen time in a Star Wars film then Luke Skywalker. (Daniel Craig is the stormtrooper that Rey pulls the Jedi mind trick on.)

3) The trailers spoiled Han Solo’s death. When Kylo Ren pulls out his lightsaber on the bridge, we have yet to see Ren’s battle with Finn in the snow. This means that Ren can’t be giving himself up here, and it would be weird if he simply re-holstered his lightsaber.

4) At the end of Return of the Jedi, Luke seems to believe Vader can go home and everything will be okay. Similarly, Mr. Solo…I mean, Han…seems to think that Kylo Ren can return home and everything will be okay. Their best case scenario is life imprisonment, and execution seems much more likely.

5) Perhaps the most unrealistic thing about A New Hope and The Force Awakens is that, within a few scant hours of receiving intelligence about the big evil weapon, the rebels have some genius plan to destroy the facility. The only way this could happen is if the vulnerability is obvious. But if the vulnerability is obvious, why don’t the bad guys spot it and fix the problem?

6) Also, when will the bad guys learn that sinking massive amounts of capital into one super weapon is not a good investment strategy?

7) How can Han manually leave light speed within a planet’s atmosphere? Given the speed involved and the small window, this is basically impossible.

Understanding the Iran Deal: A Model of Nuclear Reversal

Most of the discussion surrounding the Joint Comprehensive Plan of Action (JCPOA, or the “Iran Deal”) has focused on mechanisms that monitor Iranian compliance. How can we be sure Iran is using this facility for scientific research? When can weapons inspectors show up? Who gets to take the soil samples? These kinds of questions seem to be the focus.

Fewer people have noted Iran’s nuclear divestment built into the deal. Yet Iran is doing a lot here. To wit, here are some of the features of the JCPOA:

  • At the Arak facility, the reactor under construction will be filled with concrete, and the redesigned reactor will not be suitable for weapons-grade plutonium. Excess heavy water supplies will be shipped out of the country. Existing centrifuges will be removed and stored under round-the-clock IAEA supervision at Natanz.
  • The Fordow Fuel Enrichment Plant will be converted to a nuclear, physics, and technology center. Many of its centrifuges will be removed and sent to Natanz under IAEA supervision. Existing cascades will be modified to produce stable isotopes instead of uranium hexafluoride. The associated pipework for the enrichment will also be sent Natanz.
  • All enriched uranium hexafluoride in excess of 300 kilograms will be downblended to 3.67% or sold on the international market.

Though such features are fairly common in arms agreements, they are nevertheless puzzling. None of this makes proliferation impossible, so the terms cannot be for that purpose. But they clearly make proliferating more expensive, which seems like a bad move for Iran if it truly wants to build a weapon. On the other hand, if Iran only wants to use the proliferation threat to coerce concessions out of the United States, this still seems like a bad move. After all, in bargaining, the deals you receive are commensurate with your outside options; make your outside options worse, and the amount of stuff you get goes down as well.

The JCPOA, perhaps the worst formatted treaty ever.

The JCPOA, perhaps the most poorly formatted treaty ever.

What gives? In a new working paper, I argue that undergoing such a reversal works to the benefit of potential proliferators. Indeed, potential proliferators can extract the entire surplus by divesting in this manner.

In short, the logic is as follows. Opponents (like the United States versus Iran) can deal with the proliferation problem in one of two ways. First, they can give “carrots” by striking a deal with the nuclearizing state. These types of deals provide enough benefits to potential proliferators that building weapons is no longer profitable. Consequently, and perhaps surprisingly, they are credible even in the absence of effective monitoring institutions.

Second, opponents can leverage the “stick” in the form of preventive war. The monitoring problem makes this difficult, though. Sometimes following through on the preventive war threat shuts down a real project. Sometimes preventive war just a bluff. Sometimes opponents end up fighting a target that was not even investing in proliferation. Sometimes the potential proliferator can successfully and secretly obtain a nuclear weapon. No matter what, though, this is a mess of inefficiency, both from the cost of war and the cost of proliferation.

Naturally, the opponent chooses the option that is cheaper for it. So if the cost of preventive war is sufficiently low, it goes in that direction. In contrast, if the price of concessions is relatively lower, carrots are preferable.

Note that one determinant of the opponent’s choice is the cost of proliferating. When building weapons is cheap, the concessions necessary to convince the potential proliferator not to build are very high. But if proliferation is very expensive, then making the deal looks very attractive to the opponent.

This is where nuclear reversals like those built into the JCPOA come into play. Think about the exact proliferation cost that flips the opponent’s preference from sticks to carrots. Below that line, the inefficiency weighs down everyone’s payoff. Right above that line, efficiency reigns supreme. But the opponent is right at indifference at this point. Thus, the entire surplus shifts to the potential proliferator!

The following payoff graph drives home this point. A is the potential proliferator; B is the opponent; k* is the exact value that flips the opponent from the stick strategy to the carrot strategy:

Making proliferation more difficult can work in your favor.

Making proliferation more difficult can work in your favor.

If you are below k*, the opponent opts for the preventive war threat, weighing down everyone’s payoff. But jump above k*, and suddenly the opponent wants to make a deal. Note that everyone’s payoff is greater under these circumstances because there is no deadweight loss built into the system.

Thus, imagine that you are a potential proliferator living in a world below k*. If you do nothing, your opponent is going to credibly threaten preventive war against you. However, if you increase the cost of proliferating—say, by agreeing to measures like those in the JCPOA—suddenly you make out like a bandit. As such, you obviously divest your program.

What does this say about Iran? Well, it indicates that a lot of the policy discussion is misplaced for a few of reasons:

  1. These sorts of agreements work even in the absence of effective monitoring institutions. So while monitoring might be nice, it is definitely not necessary to avoid a nuclear Iran. (The paper clarifies exactly why this works, which could be the subject of its own blog post.)
  2. Iranian refusal to agree to further restrictions is not proof positive of some secret plan to proliferate. Looking back at the graph, note that while some reversal works to Iran’s benefit, anything past k* decreases its payoff. As such, by standing firm, Iran may be playing a delicate balancing game to get exactly to k* and no further.
  3. These deals primarily benefit potential proliferators. This might come as a surprise. After all, potential proliferators do not have nuclear weapons at the start of the interaction, have to pay costs to acquire those weapons, and can have their efforts erased if the opponent decides to initiate a preventive war. Yet the potential proliferators can extract all of the surplus from a deal if they are careful.
  4. In light of (3), it is not surprising that a majority of Americans believe that Iran got the better end of the deal. But that’s not inherently because Washington bungled the negotiations. Rather, despite all the military power the United States has, these types of interactions inherently deal us a losing hand.

The paper works through the logic of the above argument and discusses the empirical implications in greater depth. Please take a look at it; I’d love to hear you comments.

Bargaining Power and the Iran Deal

Today’s post is not an attempt to give a full analysis of the Iran deal.[1] Rather, I just want to make a quick point about how the structure of negotiations greatly favors the Obama administration.

Recall the equilibrium of an ultimatum game. When two parties are trying to divide a bargaining pie and one side makes a take-it-or-leave-it offer, that proposer receives the entire benefit from bargaining. In fact, even if negotiations can continue past a single offer, as long as a single person controls all of the offers, the receiver still receives none of the surplus.

This result makes a lot of people feel uncomfortable. After all, the outcomes are far from fair. Fortunately, in real life, people are rarely constrained in this way. If I don’t like the offer you propose me, I can always propose a counteroffer. And if you don’t like that, nothing stops you from making a counter-counteroffer. That type of negotiations is called Rubinstein bargaining, and it ends with a even split of the pie.

In my book on bargaining, though, I point out that there are some prominent exceptions where negotiations take the form of an ultimatum game. For example, when returning a security deposit, your former landlord can write you a check and leave it at that. You could try suggesting a counteroffer, but the landlord doesn’t have to pay attention—you already have the check, and you need to decide whether that’s better than going to court or not. This helps explain why renters often dread the move out.

Unfortunately for members of Congress, “negotiations” between the Obama administration and Congress are more like security deposits than haggling over the price of strawberries at a farmer’s market. If Congress rejects the deal (which would require overriding a presidential veto), they can’t go to Iran and negotiate a new deal for themselves. The Obama administration controls dealings with Iran, giving it all of the proposal power. Bargaining theory would therefore predict that the Obama administration will be very satisfied[2], while Congress will find the deal about as attractive as if there were no deal at all.

And that’s basically what we are seeing right now. Congress is up in arms over the deal (hehe). They are going to make a big show about what they claim is an awful agreement, but they don’t have any say about the terms beyond an up/down vote. That—combined with the fact that Obama only needs 34 senators to get this to work—means that the Obama administration is going to receivea very favorable deal for itself.

[1] Here is my take on why such deals work. The paper is a bit dated, but it gets the point across.

[2] I mean that the Obama administration will be very satisfied by the deal insofar as it relates to its disagreement with Congress. It might not be so satisfied by the deal insofar as it relates to its disagreement with Iran.

Serial and Credible Threats

[Serial Podcast Season 1 spoilers below]

I’m going to assume you have gone through the first season of Serial and know most of the background. However, some important recap:

According to Jay’s testimony, Adnan strangled Hae and then solicited the help of Jay to dispose of the body. The police wondered why Jay, an acquaintance of Adnan, would ever go along with that. Jay stated that he initially refused. But Adnan threatened to go to the cops about Jay’s pot dealings. Wanting to avoid that, Jay becomes an accessory to murder.

To me, this makes no sense at all. I could understand why Jay might prefer burying the body to having to deal with the police over some (relatively minor) marijuana, but the latter scenario would never happen. Adnan simply does not have a credible threat here. If Adnan goes to the police to turn in Jay, Jay can easily plead out of the crime by handing them Adnan. Jay has all the leverage here. Adnan has none.

Did Jay not realize this? I can’t imagine that is true. Jay is supposed to be street-smart. He might not understand the difference between Nash equilibrium and subgame perfect equilibrium, but he certainly should understand the difference between a credible threat and an incredible threat.

Would Jay not be willing to snitch on Adnan if Adnan turned him in? If so, then Adnan would not be deterred from pointing the police to Jay, and so maybe Jay would go along with it. But I can’t imagine this is true either. First, it would require Jay to not want to rat on the guy who just ratted on him, even though it would likely mean that Jay’s charges would be dropped. Second, we in fact know Jay was willing to snitch on Adnan—because he did!

This leads me to conclude that Jay’s lying. I’m not sure why or what it means, but I think it’s important.

TL;DR: Jay’s story is not subgame perfect.

Am I missing something here?

The Game Theory of the Cardinals/Astros Spying Affair

The NY Times reported today that the St. Louis Cardinals hacked the Houston Astros’ internal files, including information on the trade market. I suspect that everyone has a basic understanding why the Cardinals would find this information useful. “Knowledge is power,” as they say. Heck, the United States spends $52.6 billion each year on spying. But game theorists have figured out how to quantify this intuition is both interesting and under-appreciated. That is the topic of this post.

Why Trade?
Trades are very popular in baseball, and the market will essentially take over sports headlines as we approach the July 31 trading deadline. Teams like to trade for the same reason countries like to trade with each other. Entity A has a lot of object X but lacks Y, while Entity B has a lot of object Y but lacks X. So teams swap a shortstop for an outfielder, and bad teams exchange their best players for good teams’ prospects. Everyone wins.

However, the extent to which one side wins also matters. If the Angels trade a second baseman to the Dodgers for a pitcher, they are happier than if they have to trade that same second baseman for that same pitcher and pay an additional $1 million to the Dodgers. Figuring out exactly what to offer is straightforward when each side is aware of exactly how much the other values all the components. In fact, bargaining theory indicates that teams should reach such deals rapidly. Unfortunately, life is not so simple.

The Risk-Return Tradeoff
What does a team do when it isn’t sure of the other side’s bottom line? They face what game theorists call a risk-return tradeoff. Suppose that the Angels know that the Dodgers are not willing to trade the second baseman for the pitcher straight up. Instead, the Angels know that the Dodgers either need $1 million or $5 million to sweeten the deal. While the Angels would be willing to make the trade at either price, they are not sure exactly what the Dodgers require.

For simplicity, suppose the Angels can only make a single take-it-or-leave-it offer. They have two choices. First, they can offer the additional $5 million. This is safe and guarantees the trade. However, if the Dodgers were actually willing to accept only $1 million, the Angels unnecessarily waste $4 million.

Alternatively, the Angels could gamble that the Dodgers will take the smaller $1 million amount. If this works, the Angels receive a steal of a deal. If the Dodgers actually needed $5 million, however, the Angels burned an opportunity to complete a profitable trade.

To generalize, the risk-return tradeoff says the following: the more one offers, the more likely the other side is to accept the deal. Yet, simultaneously, the more one offers, the worse that deal becomes for a proposer. Thus, the more you risk, the greater return you receive when the gamble works, but the gamble also fails more often.

 

Knowledge Is Power
The risk-return tradeoff allows us to precisely quantify the cost of uncertainty. In the above example, offering the safe amount wastes $4 million times the probability that the Dodgers were only willing to accept $1 million. Meanwhile, making an aggressive offer wastes the amount that the Angels would value the trade times the probability the Dodgers needed $5 million to accept the deal; this is because the trade fails to occur under these circumstances. Consequently, the Angels are damned-if-they-do, and damned-if-they-don’t. The risk-return tradeoff forces them to figure out how to minimize their losses.

At this point, it should be clear why the Cardinals would value the Astros’ secret information. The more information the Cardinals have about other teams’ minimal demands, the better they will fare in trade negotiations. The Astros’ database provided such information. Some of it was about what the Astros were looking for. Some of it was about what the Astros thought others were looking for. Either way, extra information for the Cardinals organization would decrease the likelihood of miscalculating in trade negotiations. And apparently such knowledge is so valuable that it was worth the risk of getting caught.