International Relations 101

Looking at international relations from a strategic perspective

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  • Lectures 71
  • Video 9.5 Hours
  • Skill Level All Levels
  • Languages English
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Course Description

International relations are strategic and interdependent--how one state acts affect another state's outcome and vice versa. How do states act given this constraint? International Relations Course 101 introduces the strategic world in which we live. We will focus on nine topics in particular:

  • What is international relation?
  • Conflict versus cooperation
  • Rationalist explanations for war
  • International trade
  • The democratic peace theory
  • Principal-agent problems
  • International institutions
  • Nuclear weapons
  • Terrorism

Take this free International Relations Course and learn what is international relations & more.


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  • Over 71 lectures and 9.5 hours of content!
  • Learn why international relations is strategic.
  • Understand why game theory is useful for studying international relations.
  • Know how to properly critique theories.

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Section 1: Introduction

This video begins a new series on international relations which applies formal models to important issues in the world today. We will cover the following topics:

  • What is international relations?
  • Conflict versus cooperation
  • Rationalist explanations for war
  • International trade
  • How regime types affect international outcomes
  • International institutions
  • Nuclear weapons
  • Terrorism


Who are the big actors in international relations? The answer is sovereign states, or the entities that have a monopoly on the use of force within their territory. The notion of sovereignty began in 1648 with the Treaty of Westphalia, which ended the Thirty Years' War.

However, states often violate sovereignty. We will see why they can get away with it next time.


When one state meddles in another state's internal affairs, who punishes the first state? In other words, who is sovereign over the sovereign? The best answer: no one. International relations lives in anarchy, more closely resembling an area ruled by mafia dons than a strong local police force.

However, anarchy does not imply chaos. Anarchy permits anything to happen. Thus, the challenge for us as students of international relations is to be able to predict and explain phenomenon despite the wide-open possibilities.


What does it mean for x to cause y? Did World War I begin because a man with a funny mustache was shot or because of perceived first strike advantages?

Broadly, there are two types of explanations: proximate and underlying causes. We value underlying causes much more than proximate causes because underlying causes give us useful policy recommendations.

However, finding underlying causes is a difficult process. The next video will develop a game plan.

Minor correction: World War I started a month after Franz Ferdinand was shot, not a couple of weeks.


In international relations, states are strategically interdependent--how one state acts affects another, and how the other state acts affects the first. Game theory is the study of strategic interdependence, which is why we will heavily rely on its methodology going forward. However, game theory is not perfect. It only maps assumptions into logically valid conclusions. As such, we must make sure we only use sensible assumptions, otherwise we will wind up with potentially silly (but logically valid) conclusions.

This video wraps up the first unit in international relations. Next time, we will explore general models of conflict and cooperation.

Section 2: Conflict versus Cooperation

Under what conditions will two states cooperate even without a police force to deter conflict? This unit investigates the temptations and incentives for spontaneous cooperation. In the next few videos, we will cover the following:

  • The prisoner's dilemma
  • The Cult of the Offensive and the origins of World War I
  • Arms races and arms treaties
  • Tariffs and free trade policy
  • Trench warfare during World War I


How can individually rational choices lead to collectively bad outcomes? The prisoner's dilemma is the oldest model in game theory and provides an explanation. In the next few videos, we will apply the logic of the prisoner's dilemma to case studies in international relations.


What caused World War I? One trivial explanation is that the assassination of Franz Ferdinand caused Austria-Hungary to make demands unacceptable to Serbia, which led to many countries in Europe mobilizing each other.

However, states curiously mobilized against each other preemptively, shunning the possibility of a diplomatic solution. Why would states prefer a costly war to peace? The so-called "Cult of the Offensive"--the belief among leaders that offensive technology dominated the defense at the time--provides an explanation.


Prior to World War II, states routinely taxed goods imported into their country. Although this makes domestic products more competitive within the country's own borders, the tariff system led to an overall inefficient economic system. Why were taxes the norm back then, and why is it so difficult to establish free trade?

Modeling free trade as a prisoner's dilemma provides an explanation. Although everyone is collectively better off with free trade, individual incentives tell states to place tariffs on imported goods. Thus, although the result is collectively crazy, it is individually rational.

Yet, in the post-World War II era, free trade has become the norm. As such, this video raises a new question: how is free trade sustainable given the prisoner's dilemma logic? We will explore this type of cooperation after the next lesson.


Weapons are expensive to build but provide benefits if one state builds more weapons vis-a-vis its rival. Thus, the prisoner's dilemma describes an arms race: both sides prefer not building weapons to building weapons collectively, but individually each side is better of building regardless of what the other does.

As with the previous lecture on tariffs, you might notice that there have been plenty of successful arms treaties over the decades. We will begin explaining why cooperation can succeed in the face of a prisoner's dilemma in the next video.


In one-shot prisoner's dilemma interactions, states cannot cooperate because each has individual incentives to defect on the other. However, some interactions take place over the long term. Can states cooperate at the beginning under the threat of defection later on?

Unfortunately, the answer is no. At the end of the interaction, the states must defect on one another. The shadow of the future casts a pall on the present, leading to defection throughout. This holds no matter how long the interaction is.


Cooperation cannot occur if states know when their interaction will end. What if the end of the interaction is uncertain? Cooperation is possible if the states adopt a policy of tough love--a.k.a. a grim trigger strategy. The states begin by cooperating. Then, as long as everyone has cooperated in the past, they continue cooperating. Otherwise, they defect.

The Evolution of Cooperation by Robert Axelrod is a classic book on this subject.

Section 3: Rationalist Explanations for War

Imagine you own a store, and a man trips inside it. He sues you for $40,000 for negligence. Both your lawyer and his lawyer agree there is a 60% chance the lawsuit will be successful, but both of you will have to pay your attorneys $10,000 regardless of the outcome. How should we expect this matter to resolve itself?

Surprisingly, this lawsuit is analogous to war--both are costly and the winners are determined probabilistically if bargaining breaks down.

The Rationality of War on Amazon and Barnes & Noble


Can two perfectly intelligent, perfectly unbiased leaders fight wars against each other?

In our investigation of war, we will begin by looking at "unitary actor" explanations. Specifically, we will assume that states are single entities with no domestic political cleavages. Although that might sound heroic at first, keep in mind that leaders justify wars using these types of explanations. Moreover, if wars can happen even when countries are unified, those causes can still lead to wars even if leaders have incentives for war that their populace does not share.

The Rationality of War on Amazon and Barnes & Noble.


War's inefficiency puzzle is a research question that asks why states sometimes choose to fight when bargaining, in theory, leaves both sides better off. This video builds some intuition about the puzzle by exploring a hypothetical crisis between Venezuela and Colombia. Can the two countries agree to a peaceful settlement, or are they doomed to fight?

The Rationality of War on Amazon and Barnes & Noble. Chapter 2 available as a free PDF here.

15 pages
Learn about war's inefficiency puzzle with the algebraic, geometric, and game theoretic bargaining models of war.

Can we show that there generally exists a settlement that two sides mutually prefer to war? The answer is yes. This video proves the assertion using the algebraic crisis bargaining model. Next time, we will interpret the results using a geometric model. You can read more about this proof in the article "Rationalist Explanations for War."

The Rationality of War on Amazon and Barnes & Noble. Chapter 2 available as a free PDF here.


Can we show that there generally exists a settlement that two sides mutually prefer to war? The answer is yes. This video proves the assertion using the algebraic crisis bargaining model. Next time, we will interpret the results using a geometric model.

Download chapter two of The Rationality of War for free here.

Buy The Rationality of War on Amazon or Barnes and Noble.

You can read more about this proof in the following article "Rationalist Explanations for War."


To explain why wars break out, we need to relax some assumptions and build additional assumptions into the model. Maintaining tractability requires switching over to a game theoretical model, which we create and solve in this lecture.

Download chapter two of The Rationality of War for free here.

Buy The Rationality of War on Amazon or Barnes and Noble.

You can read more about this proof in "Rationalist Explanations for War".


When do power shifts lead to war? What is the definition of preventive war? In the standard bargaining model, we assumed that power remained static over time. Here, we abandon that assumption and investigate whether war can occur if a rising state will grow more power over time.

Preventive war is the subject of Chapter 4 of The Rationality of War. You can find it on Amazon and Barnes & Noble.


How do overly optimistic beliefs lead to war? Why can't states negotiate a settlement anyway and avoid the costs of fighting? Moreover, if over-optimism causes war and war is costly, why can't states compare their capabilities, match their expectations with reality, and reach a peaceful settlement? This lecture discusses the next rationalist explanation for war: information problems and incentives to misrepresent.

Information problems and incentives to misrepresent are the subject of Chapter 4 of The Rationality of War. You can find it on Amazon and Barnes & Noble.


If a bargaining object is all-or-nothing, then we trivially cannot bargain over it. This, in essence, is why issue indivisibility is a rationalist explanation for war. However, side payments can help resolve the issue. This lecture shows why bargaining fails in these instances, how side payments fix the problem, and applies the lessons to the end of the Spanish-American War.

Issue indivisibility is the subject of Chapter 5 of The Rationality of War. You can find it on Amazon and Barnes & Noble.


Before, we assumed that the probability of war was the same regardless of who decided to begin the fight. What if we allow for first strike advantages? If the incentives to preempt are great, then we have another rationalist explanation for war. But whether wars truly begin because of first strike advantages--or if first strike advantages merely exacerbate existing problems--remains in debate.

Preemptive war is the subject of Chapter 6 of The Rationality of War. You can find it on Amazon and Barnes & Noble.

3 questions

Test your knowledge of the bargaining model of war.

Section 4: International Trade

Why do states engage in trade? One reason might be because some states are just better at producing goods than other states. This lecture uses the California wine and Mexican tequila industries as an example. California has a good climate for grapes; Mexico has a good climate for agave (the plant that tequila is made from). Naturally, it makes sense for California to make wine and Mexico to make tequila.

But is trade still viable when there aren't the obvious advantages? The answer is yes, and we will look at that case in the next video.

If states can make some products but not others, trade inherently makes sense. But what if a single state is better at making everything? Is trade still sensible? Surprisingly, it is. States can still specialize in what they are comparatively better at making and reap the benefits from trade. This helps explain why international trade is so pervasive and why states try so hard to promote free trade agreements.
We know that trade leaves both parties better off. Then why would states bicker over trade agreements? In this lecture, we see how trade deals can be better for some parties and worse for others. As a result, states have incentive to try to steal all of the surplus of bargaining while simultaneously understanding that failure to reach an agreement leaves everyone worse off. In other words, trade rivalry creates a classic bargaining problem.
Disagreement over how to divide the surplus of trade can result in disputes. How do states mediate such conflict? International courts can help. Despite not having any actual enforcement mechanisms, these courts can coordinate states' expectations and encourage conflict resolution. This lecture draws a parallel to the "battle of the sexes" game and shows why states would want to follow through on a court's ruling.
Trade is good for everyone. But some trades leave one side relatively better off in economic terms. While this is fine from a purely economic standpoint, it can cause serious problems from a coercive military standpoint--states can use the relative advantage in trade to purchase more weapons and threaten their trade partners. How do states resolve these issues?
Section 5: The Democratic Peace Theory
The democratic peace theory is one of the best-known results in political science, both for academics and policy makers. This lecture explains the democratic peace and investigates whether it is actually true.
Democracies do not fight other democracies. But why not? This lecture briefly investigates three causal mechanisms of the democratic peace and offers a common criticism of all three theories.
A and B are correlated if A and B tend to appear together. However, correlation does not imply causation. There are many ways in which A and B can be correlated but A does not cause B. This lecture looks at a few ways correlation can obscure causation and how it relates to the democratic peace theory.
The McDonald's Peace Theory

States that trade together tend not to fight one another. But how does trade cause peace? Given what we know already, the answer is obvious. Trade creates a surplus of goods. Fighting prevents states from trading, which means states cannot benefit from the surplus. In turn, war is costlier when states trade a lot with one another. Since war is less attractive, peace is therefore more likely.

For more on the capitalist peace, read "The Capitalist Peace." (Fitting title, right?)

The Rise of China
3 questions

Test your knowledge of the democratic peace theory and its competitors.

Section 6: Principal-Agent Problems and Leader-Based Explanations
In the past, we have seen how bargaining problems and regime types affect the prevalence of war. What about individual leaders? Sometimes, leader incentives do not perfectly match the population's incentives. This creates a principal-agent problem, a mechanism common in political science and economics. We will investigate the usefulness of the theory in this unit.
How can leaders use asymmetric information for their own gain?
Sometimes leaders accidentally get involved in bad wars. Why might they continue fighting the bad fight when they know they have made a mistake?

The last two lectures are based off the aptly titled article Gambling for Resurrection.
How do democratic institutions constrain leaders' war decisions? How do these differ from autocratic institutions?

What does an average democratic leader's retirement look like? What about the average non-democratic leader's retirement?

The Iraq War provides a good example. Things went horribly wrong for both George W. Bush and Saddam Hussein, yet Bush gets to live a cushy retirement while Hussein was hanged. In general, non-democratic leaders are more likely to be jailed, exiled, or killed post-tenure than their democratic counterparts.

In the next lecture, we will discuss how this affects non-democratic leaders' incentives to initiate conflict.

For the statistics, click here .


Non-democratic leaders are more likely to be exiled, jailed, or executed when they leave office. In this lecture, we see how this can either lead to peace or war depending on the circumstances within the country.

You can find the original argument in the book Leaders and International ConflictI also wrote a book review on it.

How do leaders change the bargaining model of war we worked with in previous units?

How do electoral incentives in the United States distort foreign policy?

Stats on Cuba:

Section 7: United Nations Security Council
What is the United Nations Security Council? Why is it the most important organization within the United Nations?
Why didn't the Soviet Union veto the UNSC resolution to fight in Korea? How has veto power changed over the years? Who vetoes the most resolutions today?

In discussing the current civil war in Syria, China often mentions how the disastrous UNSC Resolution 1973, which authorized military action against Libya. Yet China did not veto the resolution. Why?

This lecture introduces how states must factor in their rivals' outside options when they vote on the Council. Sometimes, this leads to insincere voting behavior.

See this paper for the original theory.


U.S. foreign aid skyrockets when a state is a rotating member of the Security Council. Is this bribery? Is this buying good will? Is this just an innocuous coincidence?

For the original finding, see here .


At the start of an international crisis, citizens usually "rally 'round the flag" to support their leaders. Principal-agent problem mean that leaders could abuse such rallies by instigating unnecessary crises to reap the benefits of the rally. The UNSC provides third-party oversight, as approval indicates that the crisis is legitimate.

For the original article, see here (gated).

2 questions

Test your knowledge of the Security Council.

Section 8: Public Goods Provision
A public good is non-rival and non-excludable, meaning an individual's consumption of the good does not affect others' consumption and it is impossible to exclude individuals from consuming it. Non-excludable goods can be problematic in international affairs. This unit looks at how states mitigate the problem.

Absent international agreements, states have incentive to over consume common pool goods. But treaties can be worthless if no one knows when a state has violated it. Thus, monitoring institutions help create international cooperation.

This lecture explains the usefulness of monitoring institutions in relation to over-fishing in lakes.


Public goods often provide enormous benefits at small costs to their providers. However, because public goods are non-rival and non-excludable, those benefits are divided among a large group of individuals. This encourages free riding--why pay the cost when you can gain from everyone else's production?

But this leads to the collective action problem: no one ultimately produces the good, as everyone relies on someone else to do the dirty work.

When a single state enjoys a disproportionately large share of a public good, it may be willing to provide it despite knowing no one else will contribute. Large, powerful states are therefore beneficial in this way to the international system as a whole.

The repeated prisoner's dilemma showed that states can sustain cooperation though the threat of punishment in the future. But punishment in public goods interactions is complicated. For example, one state cannot adequately punish a second state for polluting without also polluting the air of other countries.

The solution is to link issues. Issue linkage allows states to make targeted punishments, which in turn allows for credible cooperation.

Section 9: Nuclear Proliferation
Who has nuclear weapons? How do nuclear weapons impact international relations?
Nuclear weapons are mankind's most destructive creation. But are they a symbol of death and destruction or are they the world's greatest peacemaker?
Mutually assured destruction is one explanation for the long-lasting peace between major powers. But what if war has become so costly--even without nuclear weapons--that it is essentially obsolete?
Nuclear weapons have their downsides. What are they? Do they outweigh the positives?

For data on the cost of the American nuclear program, see 
Atomic Audit by Stephen Schwartz.

Because nuclear weapons provide such a large amount of destructive power, we might wonder whether a state can credibly threaten to use them in a time of crisis. If the answer is no, then nuclear weapons might not provide any coercive benefits.

Looking into crisis statistics, we see two important trends: (1) nuclear weapons states are more likely to prevail in a crisis and (2) crises involving nuclear weapons states tend not to last as long as crises not involving nuclear weapons states. This lecture will provide some intuition as to why this is the case.

See "Winning with the Bomb" for the statistical analysis.

If nuclear weapons provide states with additional security, why might a state choose not to proliferate? This lecture gives three reasons: (1) the threat of preventive war, (2) the cost of nuclear weapons, and (3) incentives to bargain. This framework will give us a baseline to explain Iranian nuclear intransigence, which we will discuss in the next lecture.

here for the corresponding paper.

Bargaining is supposed to leave both parties better off than if one side develops nuclear weapons. So why is Iran acting so intransigent?

This lecture looks into the role of war exhaustion. The United States has been bogged down in Iraq and Afghanistan for almost a decade. Iran sees today as a window of opportunity to proliferate--and if they don't proliferate today, the United States will eventually leverage the threat of preventive war and stop proving concessions.

Read more about this here.


When a declining state can observe a rising state's decision to proliferate, it can leverage the threat of preventive war to stop construction of nuclear weapons. But what if the rising state could proliferate in secret?

This lecture explores strategic decision making in a guessing game framework. Sometimes, we have to expect the unexpected. We will then apply this lesson to the Iraq War in the next lecture.


If a declining state cannot observe a rising state's proliferation plans and the declining state would prefer to launch preventive war, then the states must act unpredictably or risk being exploited. As a result, preventive war sometimes occurs even though the rising state lacks a nuclear program. Although the result is rational yet appears ridiculous in retrospect.

Click here for the original article.

Section 10: Terrorism and Insurgency
Are terrorists rational? When we use the word "rational" in modeling, we do not mean it as a synonym for sensible. Instead, an actor is rational if his preferences are complete and transitive. This lecture defines completeness and transitivity, explaining that terrorists are just as strategic as any other actor.
Why do terrorist organizations use suicide tactics when they could opt for a less costly alternative? We look at three explanations: strategic benefits, signaling, and outbidding.

Read more about outbidding here .

Terrorists spoil the trust between the foreign power and a cooperative domestic government by committing attacks to trick the other side into believing that the domestic government is uncooperative. Worse, this trick is not a result of the foreign power making an irrational mistake--the target rationally calculates that the domestic government is more likely to be uncooperative having observed an attack and retaliates accordingly.

This lecture is based off of "Sabotaging the Peace: The Politics of Extremist Violence" by Andrew Kydd and Barbara Walter.

Should We Ignore Terrorists?
This unit is on terrorism and insurgency. So far we have only discussed terrorism. However, terrorism is inexorably linked to insurgency, as ongoing civil wars lead to a breakdown institutions, which in turn allows terrorism to fester. Thus, if we are to stamp out terrorism, we must also learn how to end civil wars and kill off the corresponding insurgencies.
The inability to credibly commit to cooperative actions in the future can sabotage a relationship in the present. This lecture explores commitment in police searches. The next lecture will apply the lesson to civil war termination.
While most interstate wars end in negotiated settlements, a vast majority of civil wars end in complete military defeat of one side. Why does bargaining fail? To resolve a civil war, one side must lay down its arms and reintegrate with civil society. But once that side has surrendered, it becomes completely defenseless, allowing the winning side to exploit the losers. Anticipating this, the losing side continues to fight in hopes of turning things around. The result is continued war until one side has finally been defeated.

If commitment problems cause civil wars to drag on, third parties can promote peace by standing in as peacekeepers. But not any third party will work. An enforcer must be strong, have the desire to intervene, and be willing to signal its stance.

This lecture is based on "The Critical Barrier to Civil War Settlement" by Barbara Walter.

What makes a terrorist a terrorist?
Section 11: Conclusion
What have we learned here?

Instructor Biography

William Spaniel, Game Theory 101

William Spaniel (PhD, University of Rochester 2015) specializes in formal theory and international conflict. Motivated by the United States's continued negotiations with Iran, his research investigates how bargaining has stymied nuclear proliferation for the past half-century.

He has been teaching game theory since 2009, and his lectures have been viewed millions of times around the world. In 2011, he published the best-selling textbook Game Theory 101.

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    • Gwayne Gautreaux

    Effectively efficient!!!

    Efficient, effective, systematic. Everything made sense and is applicable to real world solutions. My overall most enjoyable and favorite course on Udemy.

    • Jean A. Aboni

    Great Course

    Gives you a broad perspective of world's politics and economy and how these are very well intertwined.

    • Sanzhar Akaev

    Concise course

    This course contains of short, but very interesting lectures. Examples are

    • Ian Ulyatt

    Best course ever

    I really enjoyed this course on International Relations. it meet and went far beyond my expectation for a 101 course and was well delivered by William.
    Keep the good work up

    • Saud Al-Fattah

    Great Introductory course in IR

    Helped a great deal in understanding the International Relations and added to my knowledge in this important field. I like to commend the instructor for his profound knowledge and superb job in delivering the material of this course in an easy and understandable manner. Thanks a lot!

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