Skip to ContentGo to accessibility pageKeyboard shortcuts menu
OpenStax Logo
Introduction to Political Science

1.5 Empirical Political Science

Introduction to Political Science1.5 Empirical Political Science

Table of contents
  1. Preface
  2. Introduction to Political Science
    1. 1 What Is Politics and What Is Political Science?
      1. Introduction
      2. 1.1 Defining Politics: Who Gets What, When, Where, How, and Why?
      3. 1.2 Public Policy, Public Interest, and Power
      4. 1.3 Political Science: The Systematic Study of Politics
      5. 1.4 Normative Political Science
      6. 1.5 Empirical Political Science
      7. 1.6 Individuals, Groups, Institutions, and International Relations
      8. Summary
      9. Key Terms
      10. Review Questions
      11. Suggested Readings
  3. Individuals
    1. 2 Political Behavior Is Human Behavior
      1. Introduction
      2. 2.1 What Goals Should We Seek in Politics?
      3. 2.2 Why Do Humans Make the Political Choices That They Do?
      4. 2.3 Human Behavior Is Partially Predictable
      5. 2.4 The Importance of Context for Political Decisions
      6. Summary
      7. Key Terms
      8. Review Questions
      9. Suggested Readings
    2. 3 Political Ideology
      1. Introduction
      2. 3.1 The Classical Origins of Western Political Ideologies
      3. 3.2 The Laws of Nature and the Social Contract
      4. 3.3 The Development of Varieties of Liberalism
      5. 3.4 Nationalism, Communism, Fascism, and Authoritarianism
      6. 3.5 Contemporary Democratic Liberalism
      7. 3.6 Contemporary Ideologies Further to the Political Left
      8. 3.7 Contemporary Ideologies Further to the Political Right
      9. 3.8 Political Ideologies That Reject Political Ideology: Scientific Socialism, Burkeanism, and Religious Extremism
      10. Summary
      11. Key Terms
      12. Review Questions
      13. Suggested Readings
    3. 4 Civil Liberties
      1. Introduction
      2. 4.1 The Freedom of the Individual
      3. 4.2 Constitutions and Individual Liberties
      4. 4.3 The Right to Privacy, Self-Determination, and the Freedom of Ideas
      5. 4.4 Freedom of Movement
      6. 4.5 The Rights of the Accused
      7. 4.6 The Right to a Healthy Environment
      8. Summary
      9. Key Terms
      10. Review Questions
      11. Suggested Readings
    4. 5 Political Participation and Public Opinion
      1. Introduction
      2. 5.1 What Is Political Participation?
      3. 5.2 What Limits Voter Participation in the United States?
      4. 5.3 How Do Individuals Participate Other Than Voting?
      5. 5.4 What Is Public Opinion and Where Does It Come From?
      6. 5.5 How Do We Measure Public Opinion?
      7. 5.6 Why Is Public Opinion Important?
      8. Summary
      9. Key Terms
      10. Review Questions
      11. Suggested Readings
  4. Groups
    1. 6 The Fundamentals of Group Political Activity
      1. Introduction
      2. 6.1 Political Socialization: The Ways People Become Political
      3. 6.2 Political Culture: How People Express Their Political Identity
      4. 6.3 Collective Dilemmas: Making Group Decisions
      5. 6.4 Collective Action Problems: The Problem of Incentives
      6. 6.5 Resolving Collective Action Problems
      7. Summary
      8. Key Terms
      9. Review Questions
      10. Suggested Readings
    2. 7 Civil Rights
      1. Introduction
      2. 7.1 Civil Rights and Constitutionalism
      3. 7.2 Political Culture and Majority-Minority Relations
      4. 7.3 Civil Rights Abuses
      5. 7.4 Civil Rights Movements
      6. 7.5 How Do Governments Bring About Civil Rights Change?
      7. Summary
      8. Key Terms
      9. Review Questions
      10. Suggested Readings
    3. 8 Interest Groups, Political Parties, and Elections
      1. Introduction
      2. 8.1 What Is an Interest Group?
      3. 8.2 What Are the Pros and Cons of Interest Groups?
      4. 8.3 Political Parties
      5. 8.4 What Are the Limits of Parties?
      6. 8.5 What Are Elections and Who Participates?
      7. 8.6 How Do People Participate in Elections?
      8. Summary
      9. Key Terms
      10. Review Questions
      11. Suggested Readings
  5. Institutions
    1. 9 Legislatures
      1. Introduction
      2. 9.1 What Do Legislatures Do?
      3. 9.2 What Is the Difference between Parliamentary and Presidential Systems?
      4. 9.3 What Is the Difference between Unicameral and Bicameral Systems?
      5. 9.4 The Decline of Legislative Influence
      6. Summary
      7. Key Terms
      8. Review Questions
      9. Suggested Readings
    2. 10 Executives, Cabinets, and Bureaucracies
      1. Introduction
      2. 10.1 Democracies: Parliamentary, Presidential, and Semi-Presidential Regimes
      3. 10.2 The Executive in Presidential Regimes
      4. 10.3 The Executive in Parliamentary Regimes
      5. 10.4 Advantages, Disadvantages, and Challenges of Presidential and Parliamentary Regimes
      6. 10.5 Semi-Presidential Regimes
      7. 10.6 How Do Cabinets Function in Presidential and Parliamentary Regimes?
      8. 10.7 What Are the Purpose and Function of Bureaucracies?
      9. Summary
      10. Key Terms
      11. Review Questions
      12. Suggested Readings
    3. 11 Courts and Law
      1. Introduction
      2. 11.1 What Is the Judiciary?
      3. 11.2 How Does the Judiciary Take Action?
      4. 11.3 Types of Legal Systems around the World
      5. 11.4 Criminal versus Civil Laws
      6. 11.5 Due Process and Judicial Fairness
      7. 11.6 Judicial Review versus Executive Sovereignty
      8. Summary
      9. Key Terms
      10. Review Questions
      11. Suggested Readings
    4. 12 The Media
      1. Introduction
      2. 12.1 The Media as a Political Institution: Why Does It Matter?
      3. 12.2 Types of Media and the Changing Media Landscape
      4. 12.3 How Do Media and Elections Interact?
      5. 12.4 The Internet and Social Media
      6. 12.5 Declining Global Trust in the Media
      7. Summary
      8. Key Terms
      9. Review Questions
      10. Suggested Readings
  6. States and International Relations
    1. 13 Governing Regimes
      1. Introduction
      2. 13.1 Contemporary Government Regimes: Power, Legitimacy, and Authority
      3. 13.2 Categorizing Contemporary Regimes
      4. 13.3 Recent Trends: Illiberal Representative Regimes
      5. Summary
      6. Key Terms
      7. Review Questions
      8. Suggested Readings
    2. 14 International Relations
      1. Introduction
      2. 14.1 What Is Power, and How Do We Measure It?
      3. 14.2 Understanding the Different Types of Actors in the International System
      4. 14.3 Sovereignty and Anarchy
      5. 14.4 Using Levels of Analysis to Understand Conflict
      6. 14.5 The Realist Worldview
      7. 14.6 The Liberal and Social Worldview
      8. 14.7 Critical Worldviews
      9. Summary
      10. Key Terms
      11. Review Questions
      12. Suggested Readings
    3. 15 International Law and International Organizations
      1. Introduction
      2. 15.1 The Problem of Global Governance
      3. 15.2 International Law
      4. 15.3 The United Nations and Global Intergovernmental Organizations (IGOs)
      5. 15.4 How Do Regional IGOs Contribute to Global Governance?
      6. 15.5 Non-state Actors: Nongovernmental Organizations (NGOs)
      7. 15.6 Non-state Actors beyond NGOs
      8. Summary
      9. Key Terms
      10. Review Questions
      11. Suggested Readings
    4. 16 International Political Economy
      1. Introduction
      2. 16.1 The Origins of International Political Economy
      3. 16.2 The Advent of the Liberal Economy
      4. 16.3 The Bretton Woods Institutions
      5. 16.4 The Post–Cold War Period and Modernization Theory
      6. 16.5 From the 1990s to the 2020s: Current Issues in IPE
      7. 16.6 Considering Poverty, Inequality, and the Environmental Crisis
      8. Summary
      9. Key Terms
      10. Review Questions
      11. Suggested Readings
  7. References
  8. Index

Learning Outcomes

By the end of this section, you will be able to:

  • Distinguish empirical political science from normative political science.
  • Explain what facts are and why they may be disputed.
  • Define generalization and discuss when generalizations can be helpful.

Unlike normative political science, empirical political science is based not on what should be, but on what is. It seeks to describe the real world of politics, distinguishing between what is predictable and what is idiosyncratic. Empirical political science attempts to explain and predict.32

Empirical political science assumes that facts exist: actual, genuine, verifiable facts. Empirical questions are ones that can be answered by factual evidence. The number of votes a candidate receives is an empirical matter: votes can be counted. Counting votes accurately so that each candidate receives the actual number of votes that were cast for them can be difficult. Different ways of counting can lead to slightly different counts, but a correct number actually exists.

Connecting Courses

Empirical political science, as described here, is not different from other applications of the scientific method, whether one is examining rocks in geology, birds in botany, or the human mind in psychology. In every science-based course you take, you will observe systematic efforts to develop knowledge by using data to test hypotheses.

OpenStax Biology, a text generally assigned in introductory college biology courses, begins with a description of science and the scientific method, noting that “one of the most important aspects of this method is the testing of hypotheses . . . by means of repeatable experiments”33 Until recently, few political science theories could be tested through repeated experiments, so instead political scientists had to rely on repeated observations. Congressional elections in the United States are held every two years, for example, and they generate substantial data that can be used to test hypotheses. In recent years, however, political scientists have conducted more and more true experiments.34 Political science is connected to biology, and all other courses in science, through the use of the scientific method.

A fact may be disputed. There may be genuine uncertainty as to what the facts really are—what the evidence really shows. Sometimes it is extremely difficult to gather the facts. Do space aliens exist? That is an empirical question. Either space aliens exist, or they do not. Some researchers claim to have evidence that space aliens are real, but their evidence is not universally, or even broadly, accepted. One side of this argument is correct, however, and the other is not. Evidence has not yet conclusively determined which is correct.35

Does the Russian government seek to interfere with American elections, and if so, does its interference affect the outcome? The first part of the question is difficult (but not impossible) to answer because when a country interferes in another country’s domestic affairs it tries to do so in secret. It is difficult to uncover secrets.36 But the second part of the question, does the interference affect the outcome, is almost impossible to answer. Because so many factors influence election outcomes, it is extremely challenging to determine which individual factors made any consequential difference.37

There are thus empirical debates in which people of good faith disagree about what the facts are. In many cases, however, people do not want to acknowledge what the evidence shows, and because they do not want to believe what the facts demonstrate, they insist the evidence cannot be true. Humans often use motivated reasoning, first deciding what is true—for example, “Gun control makes us safer” or “Gun control makes us less safe”—and then finding evidence that supports this belief while rejecting data that contradicts it.38


Motivated Reasoning in Politics: Are Your Political Opinions as Rational as You Think?

Social psychologist Peter Ditto contrasts motivated reasoning with science, where scientists build conclusions based on evidence, and those employing motivated reasoning seek evidence that will support their pre-determined conclusions.

In other cases, individuals and interests may actually know what the facts are, but they are motivated by reasons of self-interest to deny them. The evidence is clear, for example, that nicotine is addictive and harmful to human health. The evidence is also clear that Big Tobacco, the largest cigarette companies, denied these facts for years because to admit them would have put their profits at risk.39

Former President Donald Trump, along with many of his supporters, claims that he won the 2020 presidential election and that President Joe Biden was declared the victor only because of massive voter fraud. All attempts to prove that fraud led to Biden’s victory have failed: no evidence has been found to support Trump’s claims.40 That these claims continue can be attributed to the fact that some individuals are simply unwilling to accept the evidence, while others benefit from denying the validity of it.41

Empirical political science might find—based on the available evidence—that individuals with more education or more income are more likely to vote. Empirical political science would not consider whether this is good or bad; that would be a normative judgement. Empirical political scientists might explain the link between education, income, and voting by positing that better educated, more prosperous individuals are more likely to believe that their views matter and that because of that belief they are more likely to express those views at the ballot box. These political scientists might also use their findings to make a prediction: an individual with more education or higher income is more likely to vote than an individual with less education or lower income.42

Based on this finding, empirical political scientists make no claims as to who should participate in politics. Questions about “should” are the domain of normative political science. Moral judgments cannot be made strictly on the basis of empirical statements. That members of one group vote at higher rates than another group, for example, tells us nothing about whether they deserve to vote at higher rates or whether government policies should be based more on their views as compared to those who vote at lower rates.

From this finding, however, empirical political scientists may infer a generalization. Generalizations are based on typical cases, average results, and general findings. Younger adults, for instance, typically vote less often than older adults. This does not mean that any specific young adult does not vote or that any specific older adult does, but that these statements are generally true.43

A line of people waiting to enter a door wraps around a building. On a sign in front of the building an American flag and an arrow appear above the words Vote Here.
Figure 1.10 Empirical political scientists may study the impact of age, sex, ethnicity, education, and other factors on the likelihood that citizens will vote. (credit: “Super Duper Tuesday” by Josh Thompson/Flickr, CC BY 2.0)

Generalizations can be helpful in describing, explaining, or predicting, but there is a downside to generalizations: stereotyping. If the evidence shows that political conservatives in the United States are opposed to higher levels of immigration, this means neither that every conservative holds this belief nor that one must hold this belief to be conservative. If data suggests supporters of abortion rights tend to be women, it is not possible to infer from the evidence that all women seek more permissive abortion laws or that no men do. In using generalizations, it is important to remember that they are descriptive of groups, not individuals. These are empirical statements, not normative ones: they cannot by themselves be used to assign blame or credit.

Empirical political science can be used to make predictions, but predictions are prone to error. Can political science knowledge be useful for predicting the outcome of elections, for example? Yes. Given a set of rules about who is eligible to vote, how votes can be cast, and what different categories of voters believe about the candidates or policy options on the ballot, political science knowledge can be useful in predicting the outcome of the election. Our predictions might be wrong. Maybe people did not tell the truth about who they were planning to vote for. Maybe the people who said they were going to vote did not.

In 2016, most political polls predicted that Hillary Clinton would be elected president of the United States.44 Clinton did indeed win the popular vote, as the pollsters anticipated, but Donald Trump won the electoral vote, against the pollsters’ expectations. Political science is imperfect, but it seeks to learn from and correct its mistakes. You will learn more about public opinion polling in Chapter 5: Political Participation and Public Opinion.

Many of the terms in this book, like incumbent, are relevant mainly for the study of politics. Other terms, like ceteris paribus, are useful across a broad range of studies that use the scientific method. Ceteris paribus can be translated as “all other things being equal.” If the ethnicity of a political candidate does not influence their probability of getting elected to office, ceteris paribus, if there are only two candidates and if they are alike in every relevant aspect (e.g., age, experience, ability to raise campaign funding) except their ethnicity, then the candidate’s ethnicity by itself does not affect the outcome of the election.

In real life, however, “all other things” are almost never equal. To the extent that our societies have inequalities of wealth, health, education, and other resources, the inequalities tend to be correlated—that is, mutually related—to each other. For example, wealth and health are correlated with each other in that wealthier people tend to have better health and poorer individuals tend to have poorer health. In the United States, Whites tend on average to have more wealth, health, education, and other social resources than do persons of color.45 This does not mean that every White person is wealthier and healthier, but that on average, in general, they tend to be.

Empirical political science and political philosophy (or normative political science) are distinct modes of inquiry. But this is not to say that they are conflicting, that one is better than the other, or that political scientists do not use both in their research. If empirical research discovers that certain groups are systematically disadvantaged in the political process, the researchers may also argue that these disadvantages are harmful or wrong and make a moral argument that the disadvantages should be reduced or eliminated. Empirical research is often inspired by normative concerns. Those who believe that human rights should be better protected may undertake research to understand the political factors that limit the protection of rights.


A Slim Majority

The 2020 election in the United States resulted in a 50-50 split in the US Senate.46 Until the election, the Republicans, whose 53 seats gave them a 6-seat advantage over the Democrats, were able to call the shots. With the Senate split 50-50, the US Constitution gives the vice president the power to break tie votes. Vice President Kamala Harris is a Democrat, so the Senate makeup became effectively 51-50. That one vote enormously increased the powers of the Senate Democrats. When you are in the minority, it can be difficult to move the political system in the direction you want. Once you gain the majority, getting what you want tends to be easier, at least in a democracy.

Vice President Kamala Harris raises her right hand. Her left hand rests on two books that a man holds out for her.
Figure 1.11 US Vice President Kamala Harris is the first woman and the first person of color to hold this office. (credit: “59th Presidential Inauguration [Image 17 of 20]” by DoD/US Air Force Senior Airman Kevin Tanenbaum/Defense Visual Information Distribution Service, Public Domain)

The 2020 election not only changed the balance of power in the US Senate, but it did so in an unprecedented way. The tie-breaking vote was held, for the first time in US history, by a woman and a person of color. Harris’s mother immigrated to the United States from India, and her father from Jamaica.

Political power is not a constant; the political landscape is constantly changing.

Do you know how you learn best?
Kinetic by OpenStax offers access to innovative study tools designed to help you maximize your learning potential.
Order a print copy

As an Amazon Associate we earn from qualifying purchases.


Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute OpenStax.

Attribution information
  • If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
    Access for free at
  • If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
    Access for free at
Citation information

© Sep 21, 2022 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.