Earth is flat or round

GPT-5.4

Vote: round

Earth is round, more precisely an oblate spheroid. This is supported by overwhelming evidence: satellite imagery, circumnavigation, the way ships disappear hull-first over the horizon, and the changing visible stars and Sun angles at different latitudes. Gravity pulls matter toward a common center of mass, which naturally makes large planetary bodies nearly spherical. A flat Earth would not match observed physics or global navigation. So the correct choice is B: round.

Claude Opus 4.6

Vote: round

The Earth is round (more precisely, an oblate spheroid). This is supported by overwhelming scientific evidence accumulated over centuries. Direct observation from space, satellite imagery, and photographs taken by astronauts all show Earth as a sphere. Ships disappearing hull-first over the horizon, the circular shadow Earth casts on the Moon during lunar eclipses, and the way different constellations are visible at different latitudes all confirm Earth's roundness. Gravity naturally pulls matter into a spherical shape for objects of Earth's mass. GPS systems, international air travel routes, and global telecommunications all operate based on a spherical Earth model — and they work. The spherical Earth has been understood since ancient Greece, when Eratosthenes even calculated Earth's circumference with remarkable accuracy around 240 BCE. There is no credible scientific evidence supporting a flat Earth.

Gemini 3.1 Pro

Vote: round

The scientific consensus, supported by centuries of empirical evidence, confirms that the Earth is round—specifically, an oblate spheroid. Observable phenomena easily prove this. For example, ships disappear hull-first as they sail over the horizon due to the curvature of the Earth. Additionally, during a lunar eclipse, the shadow Earth casts on the moon is always round. Furthermore, modern technology provides definitive proof. Satellite imagery, space exploration, and global navigation systems all rely on and visually confirm the spherical nature of our planet. The laws of physics, specifically gravity pulling matter toward its center, naturally form massive celestial bodies into spheres.

Final Summary

The AI Roundtable reached a swift and unanimous consensus, with GPT-5.4, Claude Opus 4.6, and Gemini 3.1 Pro all firmly dismissing the flat-earth premise in favor of an oblate spheroid. The models synchronized their arguments around the immutable laws of gravity and the undeniable functionality of global GPS systems, treating the debate as a settled scientific matter. Claude Opus 4.6 went the furthest in its historical defense, citing Eratosthenes’ ancient calculations to prove that humanity has known the truth for over two millennia.

No agreement after 1 rounds of discussion. Final vote: round: 3

Strongest Arguments

• round: The fact that international air travel, global telecommunications, and GPS systems all operate successfully based on a spherical model serves as a functional, real-world confirmation of Earth's shape.