Conceptualizing the Force of a Promise: Moral Obligations within the Space of Reasons

What makes a promise binding? Why do we feel morally compelled to keep promises, even when no external force compels us? These questions push us deep into the philosophical terrain of normativity, authority, and moral obligation. Central to this exploration is the conceptual framework offered by Joseph Raz and further developed through analysis of obligations, promises, and their place in the broader “space of reasons.” This blog post aims to trace how promises generate a special kind of moral force, grounded in our normative powers and the structure of practical reasons.

I. Moral Obligations in the Space of Reasons

To understand the force of a promise, we must begin with the basic vocabulary of reasons. In the philosophical landscape, reasons are considerations that count in favor of beliefs or actions. Theoretical reasons justify what we ought to believe; practical reasons justify what we ought to do. Promises clearly belong to the latter—they are reasons for action. But they are not just any kind of practical reasons. Rather, they are obligations, and obligations carry a special normative weight.

Obligations function as objective reasons. They do not merely explain why someone acts (subjective reasons), but instead justify what one ought to do, whether or not the person is motivated by them. For example, a person might keep a promise to visit a friend out of genuine affection (a subjective reason), but the deeper moral force is the promise itself—the objective reason. Importantly, reasons can and often do conflict. One may have a reason to visit a friend and a competing reason to stay home and rest. Rationality, as many theorists agree, involves acting on the strongest reason among the competing set. This is often called “the balance of reasons” (Raz, Practical Reason and Norms, 1975).

II. Normative Powers and the Creation of Reasons

How are such binding reasons created? Some are discovered (e.g., the harm principle), but others are created through the exercise of what Raz calls normative powers. These are not physical capacities, but rather the human ability to generate new reasons through speech acts—like making a promise, issuing a command, or giving consent.

The reasons generated by normative powers include various types:

Dependent reasons, which arise only in virtue of another reason;
Content-independent reasons, which apply regardless of the content of the action;
Second-order reasons, or reasons about reasons;
Exclusionary reasons, which instruct an agent to disregard certain first-order reasons.

The concept of exclusionary reasons is crucial. According to Raz, these are second-order reasons that tell us not to act on, or even consider, certain first-order reasons. For instance, when one promises to meet a friend at noon, one acquires a reason that excludes other considerations—like convenience or alternative social invitations—from deliberation. This creates what Raz terms a protected reason, which combines a first-order reason (to meet the friend) with a second-order exclusionary reason (not to be swayed by more tempting alternatives).

Moore’s analysis of exclusionary reasons offers three interpretations: the justificatory (reasons not to count certain considerations), the motivational (reasons not to be moved by certain considerations), and the cognitive (reasons not to think about certain considerations). Raz generally aligns with the justificatory interpretation, although his broader framework implies elements of the motivational and cognitive as well. His core aim is to show how certain reasons—especially those generated by valid exercises of normative powers—pre-empt others in a way that anchors both categorical moral rules and our interpersonal obligations.

III. Models of Authority: Mapping Razian Reasons

Deborah Hurd builds on Raz to outline three models of authority, distinguished by the kind of reason they provide:

Practical Authority: Offers pre-emptive reasons for action. A command or promise from a practical authority creates a reason that not only directs behavior but also excludes contrary reasons from consideration.
Influential Authority: Functions more as advice. It presents reasons for action that must be weighed alongside others but does not exclude them.
Theoretical Authority: Offers reasons for belief, such as when an expert tells us something is likely to be true.

These distinctions illuminate a range of normative contexts. For example, in the Holmes vs. Cardozo debate over negligence law, the “stop, look, and listen” rule can be seen as a practical authority when interpreted categorically (e.g., one must always stop), or as an influential authority when taken as context-sensitive guidance. Similarly, the authority of precedent in common law, divine commands, military orders, or even a friend’s request can be analyzed through this tripartite lens, depending on whether they create protected reasons or merely add to the deliberative field.

IV. The Nature of Promises

Raz provides two conceptions of promises. First, a promise may be understood as an expression of firm intention on which others will foreseeably rely. This is the reliance-based model, where the moral obligation stems from the expectations induced in others. However, Raz prefers a second model: a promise is a voluntary undertaking to perform a particular act. This conception sees promising as an exercise of a normative power—wherein one creates new, content-independent reasons for action, binding oneself through one’s own will.

The promise here is not about predicting future behavior or avoiding disappointment. Instead, it is a deliberate act of self-binding, grounded in respect for others’ autonomy. It creates exclusionary reasons that operate independently of the consequences or specific context—thus reinforcing the special kind of moral weight promises carry.

V. The Authority of the Promisor Over Themselves

A final, puzzling question remains: what kind of authority does a promisor have over their future self? How can a person, at time t₁, bind themselves at time t₂, especially if circumstances or desires have changed? This question touches the very heart of the normative force of promises.

According to Razian theory, the answer lies in the nature of the normative powers exercised at the moment of promising. When I make a promise, I generate a protected reason for my future self—one that pre-empts other reasons I might later have. In this way, I am not simply overriding my future desires; I am giving my future self a reason to act that is grounded in my autonomous will and mutual respect. The authority I wield over my future self is not coercive but normative—it is the authority of reason, structured by the moral importance of consistency, autonomy, and accountability.

Promises, then, are not just social customs or tools for coordination. They are profound moral acts, rooted in our capacity to create reasons for action that endure across time and withstand the pull of competing considerations. In promising, we exercise a kind of practical authority—not over others, but over ourselves—shaping our moral landscape in the space of reasons we share with others.

Conclusion

The force of a promise is not merely psychological or social; it is deeply normative. Drawing from Raz’s theory of reasons, Hurd’s models of authority, and the conceptual structure of obligations, we see how promises generate protected, exclusionary reasons that bind us morally. These reasons arise from our unique human ability to generate obligations through normative speech acts. In doing so, we don’t just make commitments—we create moral facts, obligations that shape what we ought to do, and in doing so, give meaning and coherence to our shared moral lives.