Restrictive versus Permissive Double Effect: Interpreting Aquinas

The paper examines the two functions of the doctrine of double effect (DDE): the permissive, which exculpates agents from negative consequences, and the restrictive, which assigns responsibility for foreseeable damages. The author contends that the common view of Thomas Aquinas as an advocate for the permissive version stems from a misreading of Summa theologiae (ST) II-II, q. 64, a. 7 (DH.7). By analyzing DH.7, the author suggests it is not about DDE but about distinguishing between instrumental harm for self-preservation and harm as a primary goal (such as punishment). The author further argues that other passages in the ST support a restrictive DDE, specifically through the concept of "closeness," where a side effect is evaluated as intended if its connection to the action is sufficiently close. This restrictive view implies that definite foresight of a negative consequence may disqualify the moral soundness of an action, contrasting with modern permissive interpretations.

• The doctrine of double effect (DDE) serves two distinct functions: a permissive function that "allows for outcomes that would ordinarily be prohibited" by exculpating agents from negative consequences, and a restrictive function that "assigns responsibility for unwanted yet foreseen outcomes."
• The author argues that the standard permissive reading of Aquinas is based on a misinterpretation of Summa theologiae II-II, q. 64, a. 7 (DH.7), which is typically viewed as the founding text of DDE.
• An analysis of DH.7 suggests it does not present a DDE framework but instead differentiates between killing as a means of self-preservation and killing where the primary intention is to visit harm, such as for "retributive punishment."
• The author posits that Aquinas embraced the concept of "closeness," meaning that if a foreseen side effect is sufficiently connected to an action, it should be treated as if it were "in some measure intended."
• Under a restrictive DDE, an agent is accountable for outcomes that are "voluntary in its cause" (secundum suam causam), where the will tends directly to the cause but indirectly to the resulting effect.
• The author suggests that for Aquinas, a negative consequence that is "per se connected to the intentional deed" cannot be separated from the act itself, meaning no amount of DDE reasoning can render the act morally sound if the consequence is inevitable.

APA

Reichberg, G. M. (n.d.). Restrictive versus Permissive Double Effect: Interpreting Aquinas. Peace Research Institute Oslo. https://cdn.cloud.prio.org/files/6103f9b6-962a-4131-9295-03e5d7fcd0f9/Restrictive versus Permissive Double Effect Interpreting Aquinas.pdf?inline=true

Chicago

Reichberg, Gregory M. Restrictive versus Permissive Double Effect: Interpreting Aquinas. Peace Research Institute Oslo, n.d. https://cdn.cloud.prio.org/files/6103f9b6-962a-4131-9295-03e5d7fcd0f9/Restrictive versus Permissive Double Effect Interpreting Aquinas.pdf?inline=true.

Wikipedia

{{cite report |last1=Reichberg |first1=Gregory M. |title=Restrictive versus Permissive Double Effect: Interpreting Aquinas |publisher=Peace Research Institute Oslo |url=https://cdn.cloud.prio.org/files/6103f9b6-962a-4131-9295-03e5d7fcd0f9/Restrictive versus Permissive Double Effect Interpreting Aquinas.pdf?inline=true |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{reichbergndrestrictive, author = {Reichberg, Gregory M.}, title = {{Restrictive versus Permissive Double Effect: Interpreting Aquinas}}, institution = {Peace Research Institute Oslo}, url = {https://cdn.cloud.prio.org/files/6103f9b6-962a-4131-9295-03e5d7fcd0f9/Restrictive versus Permissive Double Effect Interpreting Aquinas.pdf?inline=true}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }