
Lesson · 4 min Steady
Reasons You Can Share
In one line Say the aim, name the harm you foresee, and give reasons a neutral listener can check.
Two ideas from this path belong together. The double effect asks you to say what you aim at and what you only foresee. The lesson on the two lights asks you to settle with reason whatever reason can reach. Together they ask for a decision you can explain to a stranger.
Say the aim in plain words. Name the harm you foresee, without calling it small. Then give the reasons a neutral listener could check: what good it serves, whether the good is serious enough for the harm, and whether a gentler route was open. Claims that no outsider could examine are not yet reasons you can share.
Faith and conscience still count. They can move you to act. The habit here is to add the part that can be examined, so others can judge it, challenge it, or take part.
The road and the clinic

A town council votes to close a busy road for a year to build a clinic. The aim is care for the sick. The foreseen harm is longer trips and lost custom for the shops on that road.
The council publishes its reasons: the clinic’s expected patients, the shop impact, the detour routes, and a fund for affected shops. People can disagree, but they can see exactly what is being weighed.
Try this today Before your next decision that affects others, write the aim, the cost you foresee, and one reason an outsider could check.
Cite or share this lesson
A plain reference you can paste into notes or an essay:
Quest2Reason. “Reasons You Can Share.” https://quest2reason.com/learn/lesson/reasons-you-can-share. Accessed 13 November 2026.
Sources
- Thomas Aquinas, Summa Theologiae II-II, question 64, article 7 — The act with two effects: what is intended and what is only foreseen, and the need for a fitting proportion.
- Stanford Encyclopedia of Philosophy, “Doctrine of Double Effect” — A modern account of intended and foreseen effects and of the conditions usually attached to the doctrine.
- Thomas Aquinas, Summa contra Gentiles I, chapter 2 — With those who do not accept one’s scripture, one has to argue from natural reason, which everyone shares. Paraphrase.
