In the ever-evolving world of artificial intelligence, raw intelligence isn't enough anymore. Today, it's all about reasoning power—the ability of models to think through complex challenges, not just regurgitate patterns from training data. In this blog, we put three of the most advanced AI models head-to-head in a no-holds-barred reasoning gauntlet: OpenAI’s GPT-4 (o3), GPT-4 Mini (o4-mini), and Google DeepMind’s Gemini 2.5 Pro.
The test? Four categories designed to push the limits:
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Physics Puzzles
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Math Problems
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Coding Tasks
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Real-world IQ Tests
No hints. No simplified queries. Just a raw test of thinking.
The Contenders
O3 (GPT-4, March 2023 edition)
This is the classic powerhouse—the version many associate with the GPT-4 name. It’s been praised for its coherence, depth of understanding, and logical flow in reasoning tasks.
O4-Mini (GPT-4 “Tiny” variant, early 2024)
A lighter, faster version optimized for speed and cost-efficiency. While smaller than its siblings, it aims to retain strong performance in core tasks, especially in single-turn interactions.
Gemini 2.5 Pro
The latest and most advanced model from Google DeepMind as of early 2025. Designed with enhanced multimodal understanding and a focus on structured reasoning, Gemini 2.5 Pro touts improvements in chain-of-thought capabilities and real-world task handling.
Round 1: Physics Puzzles
We started with classic brain-benders—think pendulums on moving carts, buoyancy scenarios, and kinetic chain reactions.
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O3 showed remarkable consistency, offering both correct equations and intuitive explanations. It often gave the “why” behind the “what,” which is a hallmark of true understanding.
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O4-Mini struggled here. While it often knew the formulas, it had trouble chaining them together or accounting for edge-case variables.
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Gemini 2.5 Pro outshined both with visual-style reasoning. Even in text-only format, it described spatial relationships impressively, sometimes better than human undergrads.
Winner: Gemini 2.5 Pro, for its blend of conceptual grasp and clarity.
Round 2: Math Problems
Next up: high-level algebra, combinatorics, calculus integrals, and logic puzzles.
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O3 was sharp. It occasionally made small errors in symbolic manipulation but corrected itself when prompted. With step-by-step prompts, it was unstoppable.
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O4-Mini was fast but brittle. It often skipped steps or made unjustified assumptions.
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Gemini 2.5 Pro demonstrated powerful symbolic reasoning and rarely needed correction. However, on pure abstract math (like obscure number theory problems), it occasionally hallucinated plausible-sounding but incorrect proofs.
Winner: O3, for overall balance of accuracy and explainability.
Round 3: Coding Tasks
We posed real-world coding challenges: writing interpreters, optimizing algorithms, and debugging tricky edge cases.
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O3 performed well, especially with Python and JavaScript. Its code was readable, documented, and modular.
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O4-Mini generated syntactically correct code, but often lacked context-awareness. It repeated patterns, missed edge cases, or failed to verify outputs.
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Gemini 2.5 Pro flexed hard here—especially when tasks involved combining language understanding with logic (e.g., building a regex engine or writing a recursive parser). It also reasoned well about time complexity and optimization.
Winner: Gemini 2.5 Pro, especially for complex, multi-step coding logic.
Round 4: Real-World IQ Tests
We threw in analogies, visual pattern reasoning (as text descriptions), syllogistic logic, and Raven’s Matrix-style challenges.
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O3 handled verbal reasoning like a champ. It nailed analogies and deductive logic but sometimes overanalyzed simpler patterns.
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O4-Mini was hit-or-miss. Occasionally brilliant in short-form reasoning, but tripped on multi-step logic.
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Gemini 2.5 Pro had an edge in visual and spatial reasoning (even when handled via text descriptions), showing fluid understanding of abstract patterns.
Winner: Gemini 2.5 Pro, for adaptability across reasoning styles.
Final Verdict: Who Truly Reasons?
| Category | Winner |
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| Physics Puzzles | Gemini 2.5 Pro |
| Math Problems | O3 |
| Coding Tasks | Gemini 2.5 Pro |
| Real-world IQ Tests | Gemini 2.5 Pro |
🏆 Overall Champion: Gemini 2.5 Pro
While O3 remains a strong all-rounder, especially in mathematical rigor and explainability, Gemini 2.5 Pro pulls ahead in sheer versatility and structured reasoning under pressure. Its ability to simulate spatial environments, connect concepts across domains, and maintain logical consistency over long tasks makes it the current king of reasoning.
O4-Mini? Fast, lightweight, and serviceable—but clearly a tier below when deep reasoning is required.
Reasoning is the next frontier for AI. As models like Gemini 2.5 Pro push boundaries, we're witnessing a shift from reactive AI to reflective AI—models that don't just answer, but think.
The race isn’t over. O3’s successor, and a full version of GPT-5, may soon enter the ring. But for now, if you're looking for the sharpest mind in the machine learning arena—Gemini 2.5 Pro wears the crown.