The Is-Ought Problem and Justice

Hello! Welcome to your third lesson.

Introduction

In our last lesson, we established the two great families of moral reasoning: consequentialism, which focuses on outcomes, and deontology, which focuses on duties and rules. We saw that both frameworks rely on foundational "oughts"—a primary definition of "the Good" for consequentialists, and a set of primary duties for deontologists.

This raises a crucial, deeper question: where do these foundational "oughts" come from? Can we derive them from the world as it is?

Today's lesson addresses this by exploring one of the most significant challenges in moral philosophy. Our learning outcome is to describe the is-ought problem and its implications for deriving justice principles. We will investigate the argument, most famously articulated by the philosopher David Hume, that it is logically impossible to derive a statement about what we ought to do from a statement of what is the case.

Understanding this problem is fundamental. It challenges any theory of justice that claims to be grounded in objective facts—whether those facts are about human nature, divine command, history, or social conditions. Grappling with this dilemma is the first step toward understanding the sophisticated ways philosophers have attempted to justify their principles of justice.

Hume's Guillotine: Severing Is from Ought

The Scottish Enlightenment philosopher David Hume was a radical empiricist, meaning he believed all knowledge ultimately derives from sense experience. This led him to be deeply skeptical of grand metaphysical systems, including those of the "moral rationalists" of his day, who believed moral truths could be discovered by reason alone, like mathematical theorems. Hume argued instead that moral distinctions are rooted in human psychology—what he called "sentiment" or feeling.

This anti-rationalist stance culminates in a brief but explosive paragraph in his A Treatise of Human Nature, where he observes a subtle but illicit move made by moral philosophers.

As the reading shows, Hume’s point is that authors will describe a set of facts (e.g., "God is our creator," "Humans have a certain nature," "This action causes pain") and then, without any additional argument, suddenly start making prescriptions ("Therefore, we ought to obey God," "Therefore, we ought to act in accordance with that nature," "Therefore, we ought not to perform that action").

Hume declares this move "altogether inconceivable." The relationship expressed by "ought" is fundamentally different from the one expressed by "is." This observation, often called "Hume's Law" or "Hume's Guillotine," suggests that a logical argument cannot have an evaluative or prescriptive conclusion if its premises are purely descriptive or factual.

There are several interpretations of what Hume meant:

1. A Logical Point: The strongest reading is that it is a logical fallacy to infer an ought-statement from a set of is-statements. To have a valid deductive argument for a moral conclusion, you must have at least one moral premise.
2. A Non-Cognitivist Point: Perhaps Hume is arguing that "ought" statements aren't truth-claims at all. They are expressions of emotion or sentiment. If "Murder is wrong" simply means "Boo, murder!", then it can't be the conclusion of a logical proof because it's not a proposition.
3. A Point About Discovery: A weaker reading suggests that reason alone cannot discover moral truths from facts. The initial spark of moral recognition requires an input of sentiment (a feeling of approval or disapproval). Once we have moral concepts, we might be able to reason about them.

Regardless of the precise interpretation, the is-ought problem poses a profound challenge to the foundations of ethics.

The Is-Ought Gap and Moore's Open Question

The is-ought problem became a cornerstone of 20th-century metaethics. It was reinforced by a related argument from the English philosopher G.E. Moore: the Open Question Argument. Moore's argument targets any attempt to define "good" in terms of some set of natural properties (e.g., "good" just means "pleasurable" or "what we desire").

The next reading clarifies the is-ought gap and introduces Moore's powerful critique.

Let's clarify the distinction, as it's analytically useful:

• Hume's Is-Ought Problem is about inference. It states you cannot derive an "ought" from an "is."

  • Premise 1: Causing pain is a feature of action X.
  • Conclusion: Therefore, one ought not to do X. (Invalid inference)

• Moore's Open Question Argument is about definition. It states you cannot equate a moral property (like 'good') with a natural property (like 'pleasurable'). Moore argues that for any natural property N, one can always sensibly ask, "This thing is N, but is it good?". Because the question makes sense (it is "open"), 'good' and 'N' cannot mean the same thing. To claim otherwise is to commit the "naturalistic fallacy."

Both arguments work together to create a "fact-value" gap, suggesting that moral values are not just another type of fact in the natural world.

Test your understanding!

Consider the statement: "A just society is one that provides the greatest happiness for the greatest number of people."

How could you use Hume's and Moore's arguments, respectively, to challenge this claim as a foundational principle?

Show answer

• Using Hume's Is-Ought Problem: You would challenge the inference. One might present the fact: "Policy X is a policy that provides the greatest happiness for the greatest number." A utilitarian might then conclude: "Therefore, we ought to implement Policy X." Hume's argument would point out that this conclusion doesn't follow from the premise alone. You need an additional, evaluative premise: "We ought to pursue the greatest happiness for the greatest number." The is-ought problem forces the utilitarian to admit this is their fundamental, non-fact-based starting assumption.

• Using Moore's Open Question Argument: You would challenge the definition. The statement effectively defines "a just society" as "one that provides the greatest happiness..." Moore would argue that we can intelligibly ask: "I grant that this society provides the greatest happiness for the greatest number, but is it truly just?" One could imagine a scenario (like the Transplant case from our last lesson) where happiness is maximized but our sense of justice is violated. Because this question is "open" and not self-contradictory, "just" cannot simply mean "provides the greatest happiness."

Implications for Deriving Justice Principles

The is-ought problem has massive implications for any attempt to build a theory of justice. If you cannot ground your moral principles in objective facts, where do they come from?

1. The Challenge to Foundationalism

The most direct impact is the challenge to any theory that claims to derive its principles of justice directly from facts about the world.

• Natural Justice: Theories arguing that property rights are "natural" because people are self-owners or that certain social orders are just because they reflect "human nature" must bridge the is-ought gap. They cannot just state the facts of human nature; they must introduce a normative premise, such as "we ought to live in accordance with our nature."
• Consequentialism: As we saw, utilitarianism cannot derive its command to maximize happiness simply from the fact that people do desire happiness. It must begin with the normative claim that happiness is the Good that ought to be maximized.

The is-ought problem forces every theory to be honest about its foundational, non-factual, normative starting points.

2. The Non-Cognitivist Route

One radical response is to agree with Hume's guillotine and conclude that moral statements aren't factual claims at all. This is the path of non-cognitivism.

On this view, a principle of justice like "We ought to treat people as equals" is not a proposition that is true or false. It is an expression of a commitment to equality, or a prescription for others to follow. This sidesteps the is-ought problem entirely, but at a high cost: it seems to reduce justice to mere preference or emotional expression, undermining its claim to objective authority.

3. The Search for Non-Empirical Foundations

Most political philosophers do not take the non-cognitivist route. They accept that moral principles aren't derived from empirical facts, but they argue they can be justified on other, non-empirical grounds.

This reading shows that the game becomes justifying the foundational ought—the ultimate principle of justice. The main strategies, which we will encounter throughout this course, include:

• A Priori Reasoning (Kant): Justifying moral laws through pure reason, independent of experience, by analyzing the very concept of a rational being.
• Hypothetical Consent (Rawls): Grounding principles of justice not in facts, but in what principles rational agents would agree to in a fair, hypothetical choice scenario.
• Intuitionism (Moore, Ross): Arguing that some foundational moral truths are simply self-evident and can be known directly through moral intuition.

Conclusion

Today we've grappled with a foundational problem in ethics. The is-ought gap, identified by Hume, fundamentally alters the project of justifying a theory of justice.

Key Takeaways:

• The Is-Ought Problem: You cannot logically derive a prescriptive conclusion ("ought") from purely descriptive premises ("is"). Any valid moral argument must contain at least one moral premise.
• Moore's Open Question Argument: A related challenge showing that moral properties like "good" cannot be defined in terms of natural properties, as one can always question whether a thing with a natural property is truly good.
• Implications for Justice: This means no theory of justice can be "read off" from nature, history, or social facts. Every theory must justify its foundational normative principles on non-factual grounds.
• Three Paths Forward: In response to this problem, moral philosophy has broadly explored three routes:
  1. Attempt to defy Hume and find a way to bridge the is-ought gap (a minority view).
  2. Embrace the gap and adopt non-cognitivism, treating moral claims as expressions of attitude rather than truth-claims.
  3. Accept the gap and seek non-empirical foundations for moral principles, such as pure reason, hypothetical agreement, or self-evident intuitions.

This meta-ethical tool is indispensable. As we move forward, we can now critically ask of any theory: what is its foundational 'ought', and how does it attempt to justify it?

Preview of the next lesson:
Armed with this critical perspective, we will turn to the core theme of our course. Our next lesson is titled: Frame the core tension between 'natural justice' and 'social justice'. We will now be able to analyze precisely how theories of 'natural justice' attempt to ground their claims in facts about the world and why 'social justice' theories often appeal to different kinds of foundational principles altogether.