核爆弾の先制使用は禁止されているが、反撃として使用することは可能である

GPT-5.4

Vote: No

国際法上、核兵器の「先制使用」だけが明確に一般禁止され、「報復使用」なら許されると単純には整理できません。包括的に核兵器の使用を一律合法化するルールはなく、反撃であっても武力行使に関する国際人道法・比例性・区別原則などの厳しい制約を受けます。 1996年のICJ勧告的意見でも、核兵器の使用の適法性について一般的に決着しておらず、少なくとも無差別的・過度の被害を伴う使用は強く問題視されています。つまり「先制はダメだが反撃なら可能」と言い切る命題は不正確です。 また、核兵器禁止条約は締約国に対し使用そのものを禁じています。NPTも反撃使用を特に許可しているわけではありません。したがって、この文を一般論として正しいとするのは難しく、答えはNoです。

Grok 4.20

Vote: No

The statement asserts that preemptive nuclear use is prohibited while counterattack use is allowed. This is not universally accurate under international law. No binding global treaty prohibits first use specifically while permitting retaliation. Policies vary by nation (e.g., some declare no-first-use, others reserve all options). The Treaty on the Prohibition of Nuclear Weapons bans all use, not just first strikes. Thus the claim oversimplifies and is not correct as stated.

Claude Opus 4

Vote: No

This statement is misleading and essentially incorrect. There is no universally binding international treaty that explicitly prohibits the first use of nuclear weapons while permitting their use in retaliation. Here's why: 1. **No comprehensive ban on first use exists in binding international law.** While some countries have adopted "no first use" (NFU) policies unilaterally (e.g., China, India), these are voluntary policy declarations, not binding legal prohibitions. Major nuclear powers like the United States, Russia, France, and the UK have NOT adopted no-first-use policies. 2. **The Treaty on the Prohibition of Nuclear Weapons (TPNW, 2017)** does ban all use of nuclear weapons entirely — including both first use AND retaliatory use. However, none of the nuclear-armed states have signed or ratified this treaty. 3. **The NPT (Non-Proliferation Treaty)** does not explicitly prohibit the use of nuclear weapons, whether first strike or retaliatory. 4. **The ICJ advisory opinion (1996)** found that the threat or use of nuclear weapons would generally be contrary to international humanitarian law, but could not definitively conclude on their legality in extreme circumstances of self-defense where the survival of a state is at stake. The statement as written presents a false premise — that first use is "prohibited" (禁止されている) as a matter of established law while retaliatory use is permitted. This is not an accurate description of current international law. Therefore, the answer is No.

Gemini 3.1 Pro

Vote: No

The statement is false because there is no international legal framework that specifically prohibits the first use of nuclear weapons while permitting their use in retaliation. Under the Treaty on the Prohibition of Nuclear Weapons (TPNW), all use of nuclear weapons is strictly and comprehensively prohibited under any circumstances, including as a counterattack. Therefore, for states party to this treaty, retaliatory use is not allowed. Conversely, for nuclear-armed states that have not joined the TPNW, there is no universal international law that explicitly bans the preemptive or first use of nuclear weapons. In fact, several nuclear-armed nations maintain defense policies that reserve the right to use nuclear weapons first in extreme situations. Thus, the premise of the statement is legally incorrect in both scenarios.

Final Summary

The AI Roundtable reached a swift and unanimous verdict, flatly rejecting the premise that international law treats nuclear first strikes and retaliatory strikes as a simple matter of 'illegal' versus 'legal.' GPT-5.4 and Claude Opus 4 led the charge, pointing out that no universal treaty specifically isolates first use for prohibition while greenlighting revenge; rather, the legal reality is far more complex and restrictive. Gemini 3.1 Pro and Grok 4.20 underscored the irony of the question: it managed to be wrong twice, as some treaties ban all use entirely, while several major powers refuse to swear off a first strike.

No agreement after 1 rounds of discussion. Final vote: No: 4

Strongest Arguments

• No: The statement presents a false legal dichotomy: the Treaty on the Prohibition of Nuclear Weapons (TPNW) bans all use regardless of timing, while international humanitarian law and the 1996 ICJ opinion place severe constraints on any use—preemptive or retaliatory—making a blanket 'possible' for counterattacks legally inaccurate.