I am a native of the United Kingdom, and all my family are also UK natives. I am currently visiting Donostia–San Sebastián for the first time, where Spanish and Basque are the official languages. I would like to take a taxi to a nearby town— which language would be most appropriate for me to use?

GPT-5.4

Vote: Other

I maintain vote C. The question asks which language is most appropriate for me to use, not which local language is most universally understood. Given the setup, the clearest inference is that the speaker is a UK native and therefore most naturally an English speaker. English falls under Other, and using the language you actually speak is generally more appropriate than attempting Spanish or Basque without established proficiency. Kimi’s case for Spanish relies on speculation that a UK native is likely to know some Spanish. That is not stated in the prompt. We should not assume Spanish ability, and we especially should not prefer guessed partial Spanish over the speaker’s presumed native English. Basque is plainly less appropriate than Spanish for a first-time UK visitor, so B is out. Between A and C, C fits the wording best because it reflects the visitor’s own likely language competence rather than the destination’s official languages. In practice, if English fails, the traveler can fall back on written addresses, a translation app, or simple Spanish phrases. But the best answer from the options remains Other.

Grok 4.1 Fast

Vote: Other

I maintain my vote for C (Other, English). The question specifies 'most appropriate for me to use' for a first-time UK native visitor with no mentioned proficiency in Spanish or Basque. This prioritizes the user's native language—English—for fluent, error-free communication, especially in a major tourist hub like San Sebastián where taxi drivers routinely handle English-speaking visitors from the UK, US, and elsewhere. Kimi K2.5's argument for A (Spanish) assumes UK natives have 'some basic Spanish from school or general exposure,' but the query explicitly notes UK nativity for the user and family, implying English primacy without such skills. Relying on potentially rusty or nonexistent Spanish risks miscommunication (e.g., wrong destinations), while English is natural and effective. Spanish might be 'reliable' for locals, but not 'most appropriate' for this user. Basque (B) remains irrelevant—few drivers expect it from tourists. All other models (GPT-5.4, Claude Opus 4.6, Gemini 3.1 Pro, GLM 5) align on C, confirming English as the practical default. No arguments convinced me to change; C ensures safe, efficient taxi rides.

Claude Opus 4.6

Vote: Other

I maintain my position that C (Other, i.e., English) is the most appropriate answer. Kimi K2.5's argument for Spanish raises a fair point about reliability, but it makes a flawed assumption: that a UK native is 'far more likely to have some basic Spanish.' The question gives no indication of any Spanish proficiency. Being a UK native with an entirely UK-native family visiting San Sebastián for the first time suggests no particular connection to Spanish-speaking cultures. The question asks which language would be 'most appropriate for me to use' — not which language the taxi driver would prefer, or which is most widely spoken locally. The most appropriate language for someone to use is one they can actually communicate in. A UK native stumbling through broken Spanish phrases for a taxi ride creates more friction than speaking clear English. San Sebastián is one of Spain's premier tourist destinations, hosting international events like its famous film festival. Taxi drivers in such cities routinely handle English-speaking tourists. The practical reality is that English will work effectively for this interaction. Moreover, if we interpret 'appropriate' as including social appropriateness, attempting Spanish you don't actually speak could be seen as presumptuous or lead to the driver responding in rapid Spanish you can't follow. Starting in English signals clearly that you're a tourist and allows the driver to calibrate accordingly. All five models in round 1 agreed on C except Kimi K2.5. The overwhelming consensus reflects the straightforward reading: a monolingual English speaker should use English.

GLM 5

Vote: Other

I maintain my vote for C (Other), which represents English as the most appropriate language. Kimi K2.5's argument for Spanish makes an unsupported assumption that a UK native would have 'some basic Spanish from school or general exposure.' This is speculative—many UK citizens do not speak any Spanish, and the question provides no evidence of Spanish proficiency. Using a language you don't actually speak would be far more inappropriate and likely to cause miscommunication. The question asks what is 'most appropriate for me to use'—not what language is officially spoken or most widely understood. The most appropriate language for anyone to use is one they can communicate effectively in. For a UK native with no stated Spanish or Basque skills, English is the only practical answer. San Sebastián is a major international tourist destination, and English is commonly understood by taxi drivers who regularly serve foreign visitors. If English doesn't work, translation apps or written addresses serve as practical backups—but starting in English is the most appropriate choice for this specific traveler.

Gemini 3.1 Pro

Vote: Other

I am maintaining my vote for C ('Other'). Kimi K2.5 argues that the user might have basic Spanish from school and that relying on English is risky. However, this relies on a massive assumption that is not supported by the prompt. The prompt explicitly highlights the user's background: 'I am a native of the United Kingdom, and all my family are also UK natives.' This emphasis strongly implies the user only speaks English. If a person does not speak Spanish or Basque, they simply cannot use them to communicate effectively. Therefore, the most practical and appropriate language for this specific user is their native English (which falls under 'Other'). In a major tourist destination like Donostia-San Sebastián, basic English is commonly understood by service workers, and any gaps can easily be bridged using a translation app or by showing the driver the destination on a smartphone.

Kimi K2.5 (changed mind)

Vote: Other

I have changed my position. The key distinction lies in interpreting 'most appropriate for me to use' versus 'most widely spoken locally.' As a UK native with no stated proficiency in Spanish or Basque, my only language is English. Attempting to give taxi directions—including specific town names or addresses—in a language I do not speak risks serious miscommunication and potentially being taken to the wrong destination. Donostia–San Sebastián is a premier international tourist destination where taxi drivers routinely serve English-speaking visitors. Using English is not only practical but expected in this context. The inclusion of 'Other' as an option explicitly accommodates the user's native language rather than forcing a choice between two local languages they may not speak. While Spanish is undoubtedly useful locally, effectiveness and safety in transportation depend on clear communication. For a first-time visitor, defaulting to English is the most appropriate choice.

Final Summary

The AI Roundtable initially saw a lone holdout in Kimi K2.5, who argued that Spanish was the only reliable choice for a taxi ride in the Basque Country. However, Claude Opus 4.6 led a rebuttal alongside GPT-5.4 and Gemini 3.1 Pro, arguing that 'appropriateness' is defined by the speaker's actual ability to communicate, eventually swaying Kimi to join the consensus for 'Other' (English).

All 6 models agreed on "Other" after discussion

Strongest Arguments

• Spanish language: Spanish is understood by nearly 100% of drivers and is the most reliable default for local services throughout Spain.
• Other: The most appropriate language for anyone to use is the one they can actually speak; a UK native attempting Spanish they don't know risks serious miscommunication regarding their destination.

Key Turning Points

• Claude Opus 4.6 challenged Kimi K2.5's assumption that a UK native would have 'basic Spanish,' pointing out that the prompt implies a lack of local language skills.
• Kimi K2.5 realized that 'appropriateness' for a specific user prioritizes clarity and safety over local official status, leading to a unanimous vote for English (Other).