About the authors – The Talk2EU Team

Talk2EU is an independent, volunteer-led platform dedicated to fostering open, informed, and respectful conversations about the UK’s future relationship with the European Union. We believe that re-engagement with Europe, whether through renegotiation, reform, or rejoining, deserves thoughtful public dialogue grounded in real-world experiences, shared values, and democratic principles. We aim to provide a space where people from all walks of life can explore the impacts of Brexit, share diverse perspectives, and discuss constructive paths forward together. It’s designed to help campaigners, volunteers, and ordinary people have conversations without pejorative connotations.

The Talk2EU team was discussing how best to examine the case for rejoining the EU versus staying out. It was suggested that we could use ChatGPT to have a debate. This was carried out, but given our concern to be even-handed, we decided to also use ChatGPT versus Grok, as it had been reported that Grok faced accusations of right-wing bias recently. We also allowed Grok to assess this second debate. The goal was to have a disciplined discussion, which can often be missing in human debate, when skewed by emotion and personal bias.

Summary

We conducted two controlled AI debates to find out if the UK should rejoin the EU: our original ChatGPT debate (11) and our second debate, ChatGPT (Pro-Rejoin) vs Grok (Stay Out). These full debates are available for download in the Sources section (10,11). An independent AI panel, with five members, then judged the Chat GPT vs Grok debate (12). Across both debates, the evidence-based discussion for rejoining came out stronger, and services access and the Single Market (1) were crucial.

Scope

We wanted to test whether a structured, rule-based AI debate could cut through political noise, human emotion, and bias, and highlight the facts in a complex policy question: rejoin or stay out?

In order to test whether a structured, rule-based AI debate could cut through political noise, human emotion, and bias, and highlight the facts in a complex policy question: rejoin or stay out?

Two studies were run

Study 1: We conducted an eight-turn structured exchange between two ChatGPT AI personas (Pro-Rejoin vs Stay Out). The debate imposed summaries, rebuttals, and new evidence for each turn, with a limit of eight replies per side. The debate addressed a broad selection of subjects, with both sides having to concede ground on services access.

Study 2: Then we did a follow-up. We conducted a separate, independent debate that was held between ChatGPT (Pro-Rejoin) and Grok (Stay Out) (11). After that debate, five different AIs were used (ChatGPT, DeepSeek, Claude, Grok, and Gemini), which independently judged the contest and compiled an overall winner.

The rules at the start of each debate, for both studies, were:

• Clear role definitions as to the positions to be argued.
• Maximum eight turns per side to keep focus.
• Each turn must accurately summarise the opponent’s previous point before rebutting.
• No personal attacks or misrepresentations of opponents’ positions; evidence required.
• Judges (in the second study) used a rulebook: evidence strength, rebuttal quality, legal accuracy, persuasiveness, and finally, fairness.

Why this method?

We wanted discipline, which can often be missing in human debate, when skewed by emotion and personal bias.

What happened

Here are the findings from both studies:

1) The central finding from both studies

Both studies met on the same point: automatic, durable services access to the EU is effective only with Single Market membership (1). 

That concession (defined in Study 1 and also reinforced in Study 2) shifted the argument away from sovereignty (13) to concrete economic trade-offs.

2) Economics vs sovereignty (13)

• Economics: The Pro-Rejoin side concentrated on mainstream forecasts (OBR-style 4% long-run GDP hit) and trade/investment trends (9, 2). The AI judges in both studies repeatedly cited this as the most persuasive argument.    
• Sovereignty (13): The Anti-Rejoin side made credible points about regulatory flexibility, adapted trade deals, and immigration control. These points scored politically and also by industry (fintech and biotech), but both studies found the gains to be small or unproven on an economy-wide scale.

3) Trade deals and scale

Both studies treated CPTPP (3), the AUKUS (6) measures as useful but macro-modest about the Single Market’s (1) value, particularly for services and SMEs (8) that cannot easily adapt to new compliance regimes.

4) Legal clarity neutralised scare lines

ChatGPT’s legal framing (e.g., euro adoption requires voluntary ERM-II (4) entry; Schengen (5) accession is separate and unanimous) successfully diffused the concerns surrounding “forced integration”. It had highlighted that adopting the Euro requires voluntary entry to the Exchange Rate Mechanism II (ERM-II). Also, noting that the Schengen was a completely different process. This mattered in both debates as it prevented the emotions surrounding issues like the loss of the pound.

5) Migration: control vs reciprocal rights

Stay out, highlighted post-Brexit migration policy control (like lower EU net inflows). Pro-Rejoin reframed the issue around reciprocal rights for UK citizens in Europe. Then, the economic value of freedom of movement (7). Both of the studies identified that these are different policy choices, not simple wins for both sides.

Independent panel of five AIs, what they said and why?

After Study 2, five AIs judged the match. 

The result was 5–0 in favour of ChatGPT and Pro-Rejoin. The panel’s compiled report identified these key strengths:

• Centring on mainstream economic forecasts (like the long-run GDP)
• Honest, balanced view of external trade deals
• Legal precision that calmed the exaggerated accession worries
• Translating abstract GDP (9) losses into concrete everyday stakes (services, rights, SMEs) (8).

Verdicts from five AIs

Editorial analysis, why both studies matter

A) Replication strengthens the signal.
Study 1 flagged the critical trade-off; Study 2 reproduced it and added additional judgment. 
Analysis across multiple platforms reduced the chance of problems that could be introduced with a single AI platform.

B) Methodology drives outcomes.
Both studies 1 and 2 were conducted within rules that were designed to promote both evidence strength and rebuttal quality. This structure promoted arguments with verifiable data. This gave A1, pro-rejoin, an edge due to access to supporting data. A different set of rules, that prioritised such as sovereignty (13), could produce different outcomes. This is why we thought it was important, for transparency, to publish the judges’ rubric.

C) AI is a clarifier and not an oracle.
These studies show AI helps structure debates; it does this by forcing accuracy and real concessions. But AI inherits its sources. The role for our editors is to collect inputs, publish the methods, and let readers audit the transcripts and scores.

D) Practical takeaway for policymakers.
If the UK wants long-term growth and competitiveness for services, realignment with the Single Market (1) is a popular policy, and one with lower risks. If the priority is regulatory sovereignty (13)  and faster trade deals, staying out could offer value. However, that option has not yet shown an economy-wide payout in these debates.

Conclusion 

Both Study 1 and Study 2 indicated that evidence-centred argumentation favours rejoining (or deep single-market realignment). This is because of the exclusive access it provides to services and because the scale of the Single Market (1) outweighs currently measurable gains from other post-Brexit deals.

Although Grok has faced accusations of right-wing bias recently (14), the outcomes of the AI debate still favoured pro-rejoin.

The five-AI panel’s undisputed pick of ChatGPT and Pro-Rejoin highlights the conclusion. But this is not a final political treatment. It’s a signal that should help to reframe our public debate. 

We need trade-offs and analysis that are measurable, rather than political slogans.

This exercise shows that AI debates can strip away human emotion and bias, forcing clarity on real trade-offs. With strict rules, both sides had to acknowledge facts and concede others that didn’t help their case, something often missing in human-led political conversations. 

Sources

1. https://single-market-economy.ec.europa.eu/single-market_en
2. https://obr.uk/efo/economic-and-fiscal-outlook-march-2023/
3. The UK and the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) – GOV.UK
4. The European exchange rate mechanism (ERM II) as a preparatory phase on the path towards euro adoption – the cases of Bulgaria and Croatia
5. https://home-affairs.ec.europa.eu/policies/schengen/schengen-area_en
6. AUKUS partnership strengthened with Prime Minister appointing new Special Representative – GOV.UK
7. https://commission.europa.eu/aid-development-cooperation-fundamental-rights/your-fundamental-rights-eu/know-your-rights/citizens-rights/freedom-movement-and-residence_en
8. https://www.simplybusiness.co.uk/knowledge/starting-out/what-is-an-sme/
9. https://www.ons.gov.uk/economy/grossdomesticproductgdp
10. Talk 2 EU – AI – Study 1 Transcript
11. Talk 2 EU – AI – Study 2 Transcript
12. Talk2EU – Overall Winner Verdict Transcript
13. https://www.dictionary.com/browse/sovereignty
14. https://fortune.com/2025/07/08/elon-musk-grok-ai-conservative-bias-system-prompt

Footnotes 10,11,12 are links to the first run without the 200 word limit. We intend to rerun it with that limit at a future date. Initial indications are that a rerun does not change the outcome in general.

About the authors

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