Original ethical synthesis
The Proportionate Refusal Framework
To determine when an additive-manufacturing system may ethically refuse a job, this research adopts the Proportionate Refusal Framework, an original synthesis and application of four ethical approaches presented in How to Be Perfect: utilitarian concern for consequences, Kantian respect for persons and universal rules, Scanlonian contractualism, and Aristotelian virtue ethics.
Four requirements
When refusal becomes ethically permissible
Every requirement must be satisfied. Passing only some of the test is not enough.
Evidence-based harm reduction
The framework’s first requirement, evidence-based harm reduction, asks whether a design presents a credible risk of grave or irreversible harm and whether automated refusal would materially reduce that risk after false positives, circumvention, cybersecurity vulnerabilities, and displacement to unregulated machines are considered.
Schur emphasizes the uncertainty of consequentialist predictions: “The great majority of human actions involve incomplete information” (59).
Refusal must therefore rest on independently tested evidence, not fear, resemblance, or an assumed connection between intervention and result.
Respect for persons
Second, respect for persons requires a restriction narrow enough to be universalized without treating every user merely as a means of achieving public policy.
Schur explains that Kant “holds humans in the highest possible regard and rejects any action that demeans them or turns them into tools used to achieve some other goal” (79).
The system must therefore protect privacy, ownership, lawful research, repair, and expression through the least restrictive effective intervention.
Reasonable acceptability
Third, reasonable acceptability asks whether the rule could be justified to every affected stakeholder, including potential victims, lawful users, researchers, manufacturers, and people whose designs are mistakenly blocked.
Schur presents Scanlon’s goal as enabling people “to look each other in the eye and justify our basic rules for how to live” (96).
This requirement calls for publicly understandable standards, data minimization, meaningful explanations, human review, timely appeals, and accountable governance rather than an unchallengeable technological black box.
Practical wisdom
Fourth, practical wisdom evaluates the character and judgment embodied in the system.
Schur praises Aristotle’s “constant learning, constant trying, constant searching” because it produces “a mature yet still pliable person” who does not rely on outdated information (40).
Applied institutionally, this virtue requires lawmakers, manufacturers, and engineers to acknowledge uncertainty, audit errors, correct bias, and revise or withdraw restrictions as evidence changes.
Conjunctive decision rule
Together, these requirements form a conjunctive decision rule.
Machine-level refusal is morally permissible only when all four requirements are satisfied.
Apply the rule to physical and economic harms
A narrowly designed restriction addressing severe physical harm may meet this standard.
Restrictions responding primarily to economic harms, such as suspected copyright infringement, ordinarily require less intrusive remedies unless their proponents satisfy the same burden of proof.
Legality alone cannot make automated refusal ethical: the restriction must also be effective, proportionate, rights-respecting, contestable, and responsibly governed.