---
title: "Hans Morgenthau | Intro to International Relations"
description: "Hans Morgenthau was a classic realist who argued that states pursue national interest and power in an anarchic world, shaping Intro to International Relations."
canonical: "https://fiveable.me/introduction-international-relations/key-terms/hans-morgenthau"
type: "key-term"
subject: "Intro to International Relations"
unit: "Unit 3"
---

# Hans Morgenthau | Intro to International Relations

## Definition

Hans Morgenthau was a founder of classical realism in international relations. In Intro to International Relations, he is used to explain why states pursue power, national interest, and balance of power politics.

## What It Is

Hans Morgenthau is the political scientist most closely linked with classical realism in Intro to International Relations. His basic claim is simple: world politics is driven by states acting in their own national interest, and that interest is usually shaped by power, security, and survival.

Morgenthau’s version of realism starts with human nature. He argued that people are self-interested, so states, which are run by people, also tend to compete, bargain, and protect themselves. That means foreign policy is not usually guided by pure morality or shared ideals. It is shaped by what a state can get, keep, or defend.

This is why Morgenthau is so often connected to power politics. Power is not just military force in his thinking, but the ability to influence outcomes in a world where there is no central world government. In an anarchic system, states cannot rely on someone above them to keep order, so they watch other states closely and try to avoid being vulnerable.

Morgenthau also made the balance of power a central idea. If one state becomes too strong, other states may form alliances or increase their own capabilities to prevent domination. In this view, stability comes less from idealism and more from caution, competition, and counterweighting power.

A useful way to read Morgenthau is to ask what he would notice first in a foreign policy case. He would look for the state’s interests, the distribution of power, and the likely consequences of trusting other actors too much. If a country expands a military alliance, reacts to a rival’s rise, or trades moral language for strategic gain, that is classic Morgenthau territory.

He is also a bridge figure in the course. Later realism, especially Kenneth Waltz and defensive realism, shifts the explanation away from human nature and toward the structure of the international system. Morgenthau gives you the earlier, more human-centered version of realism, which is why he matters so much in the classical realism unit.

## Why It Matters

Hans Morgenthau gives you the logic behind a lot of realism questions in Intro to International Relations. If a scenario shows countries competing over territory, influence, alliances, or military strength, Morgenthau’s ideas help explain why they act the way they do without assuming they trust each other or share the same goals.

He is also the foundation for the course’s discussion of national interest. When a government chooses a policy because it protects security, expands influence, or limits a rival, that is the kind of reasoning Morgenthau describes. His work helps you separate moral language from strategic behavior, which comes up often in essays about intervention, deterrence, alliance building, and great power rivalry.

Morgenthau matters because he sets up later comparisons. Once you understand his version of classical realism, it becomes easier to see how neorealism changes the argument, and why Kenneth Waltz is often treated as a response to Morgenthau. He is also useful for reading current events, especially when you need to explain why states respond to rising powers like China with caution instead of cooperation alone.

## Connections

### Realism

Morgenthau is one of the main voices behind realism, so his ideas are often the clearest example of the theory in class. Realism says states act in an anarchic system where survival and power matter most. Morgenthau gives that theory a human-centered explanation, arguing that leaders pursue interest and security because that is how political life works.

### [National Interest](/introduction-international-relations/key-terms/national-interest)

This is one of Morgenthau’s biggest ideas. He argued that foreign policy should be guided by national interest rather than wishful thinking or universal morality. In a case study, you might use this term to explain why a state supports an alliance, avoids a war, or accepts a compromise that protects strategic goals.

### Balance of Power

Morgenthau treated balance of power as a way states prevent any one actor from dominating the system. When one country grows too strong, others respond by banding together, rearming, or shifting alliances. That makes this idea a direct extension of Morgenthau’s thinking about power politics and stability.

### [Kenneth Waltz](/introduction-international-relations/key-terms/kenneth-waltz)

Waltz is often compared with Morgenthau because both are realism thinkers, but they explain state behavior differently. Morgenthau roots competition in human nature, while Waltz explains it through the structure of the international system. If a question asks you to compare classical realism and neorealism, this pair is the one to know.

## On the AP Exam

A short-answer question or essay prompt may give you a foreign policy case and ask why a state acted strategically instead of idealistically. That is where you bring in Morgenthau: identify the national interest, explain the power calculation, and show how the state responded to an anarchic system.

If the prompt asks you to compare realist theories, use Morgenthau to represent classical realism and contrast him with Kenneth Waltz. If a country balances against a rising rival, mention balance of power and explain how Morgenthau would interpret that move. The strongest answers connect the theory to a real scenario, such as alliance formation, deterrence, or rivalry between major powers.

## Hans Morgenthau vs Kenneth Waltz

These two are easy to mix up because both are realism thinkers, but they explain the cause of state behavior differently. Morgenthau says states compete because human nature is self-interested, while Waltz says the anarchic structure of the international system pushes states to act that way. Use Morgenthau for classical realism and Waltz for neorealism.

## Key Takeaways

- Hans Morgenthau is a founder of classical realism in Intro to International Relations.
- His main idea is that states pursue national interest and power in a world without a central authority.
- He links foreign policy to human nature, so competition and caution are built into politics.
- Balance of power is a major Morgenthau idea, especially when states try to stop one power from dominating.
- He is the clearest contrast point for Kenneth Waltz and later neorealist thinking.

## FAQs

### What is Hans Morgenthau in Intro to International Relations?

Hans Morgenthau is the classic realist thinker most often used to explain power politics, national interest, and balance of power. In this course, he shows up when you are studying why states compete and why morality often takes a back seat to security and strategy.

### What is the difference between Morgenthau and Kenneth Waltz?

Morgenthau explains state behavior through human nature, while Waltz explains it through the structure of the international system. That means Morgenthau is classical realism and Waltz is neorealism. If a question asks why states behave similarly under anarchy, Waltz is usually the better fit.

### How does Hans Morgenthau explain foreign policy?

He argues that foreign policy should be guided by national interest, not just idealism or moral claims. States look for advantage, security, and survival, especially when other states might act aggressively. That makes his theory useful for alliance choices, military buildup, and rivalry cases.

### Why does Morgenthau matter for balance of power?

Morgenthau thought states try to keep power from concentrating in one place for too long. If one state rises too far, others balance against it by forming alliances or increasing their own strength. That idea shows up whenever the course discusses stability in an anarchic international system.

## Related Study Guides

- [3.2 Balance of Power and Polarity in International Relations](/introduction-international-relations/unit-3/balance-power-polarity-international-relations/study-guide/5vleKkLOZ9Ot2Flr)
- [2.1 Classical and Neorealism](/introduction-international-relations/unit-2/classical-neorealism/study-guide/DbBfHO9Db2o98jBK)

## About This Document

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