The Reasoning Pivot
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The transition from GPT-4 to GPT-5 was not a simple upgrade in scale—it was a fundamental shift in paradigm. Where earlier models were trained once and then deployed, the new era of AI reasoning treats the model as a continuous learner, refining its understanding through reinforcement learning, real-world feedback, and iterative self-correction. As OpenAI co-founder Greg Brockman explained, the moment they completed GPT-4, they knew the path to AGI required a different approach.
From Next-Token Prediction to Real-World Reasoning
The journey began with a question. After training GPT-4, OpenAI's team asked themselves: why is this not AGI? The model could hold coherent conversations and answer questions, but it lacked reliability. It made mistakes and fell off the rails. The answer was clear: the system needed to test its ideas in the world, receive feedback, and learn from its own attempts.
This was not a new insight. OpenAI had already demonstrated the power of reinforcement learning in their Dota project, where agents learned complex behaviours from randomly initialised neural networks without any human demonstrations. The challenge was to bring that same reliability to language models.
The solution was a new reasoning paradigm: first, train the model through supervised data to learn conversation; then, use reinforcement learning to let the model repeatedly test itself in its environment, generating data and training on that data in a continuous loop. As Brockman put it, the industry is moving "from a world where it's just you go and train once and then you're inferencing a ton to a world where there's actually this loop of you inference and you train on those inferencings".
The Architecture of a Reasoning Model
The shift required a fundamentally different architecture. GPT-5 represents OpenAI's first hybrid model, using a hierarchical routing system that dynamically allocates compute resources based on task complexity. Simple queries receive fast responses from efficient non-reasoning models, while complex problems trigger a deeper reasoning process involving reinforcement learning, internal chain-of-thought, and self-correction.
This "test-time compute" approach—using additional computational resources during reasoning rather than just during training—marked a watershed moment. OpenAI's o1 models demonstrated that giving a model more time to "think" could achieve performance gains comparable to scaling the model by 100,000x. The model learns to recognise and correct its mistakes, break down tricky steps into simpler ones, and try alternative approaches when the current one isn't working.
The empirical results were striking. On AIME 2024, o1 averaged 74% correct with a single sample per problem, compared to GPT-4o's 12%. The model surpassed human PhD-level accuracy on GPQA diamond, a benchmark testing expertise in physics, chemistry, and biology. In the words of OpenAI research vice president Jerry Tworek, in some ways, GPT-5 can be viewed as o3.1—an iteration of the reasoning series rather than a simple language model upgrade.
The RL+Pretraining Synergy
A critical insight emerging from OpenAI's work is that reinforcement learning and pretraining are not alternatives—they are complementary and mutually necessary. Jerry Tworek has explicitly rejected the view that "pure RL is the only path to AGI," stating that "RL needs pretraining to succeed, and pretraining needs RL to succeed. Both are indispensable".
The synergy works through a two-stage process. First, pretraining builds foundational capabilities—language understanding, world knowledge, and basic reasoning—by learning patterns across vast amounts of text. Then reinforcement learning refines the model's behaviour by rewarding correct outputs and penalising incorrect ones, effectively making the model more reliable and aligned with human expectations.
This division of labour is crucial for governance. Pretraining provides the knowledge base; reinforcement learning provides the behavioural reliability. Future AGI systems will likely require both, along with additional components yet to be developed.
The "Supercritical Learning" Horizon
Brockman introduced another concept: "supercritical learning." The model must not only learn what is immediately taught, but also derive second-, third-, and fourth-order consequences, updating its entire knowledge system through deeper reflection. This advanced learning process requires even more computational resources.
Brockman described computation as the "basic fuel" that converts energy into potential intelligence stored in model weights. Once trained through large-scale computation, models can be reused repeatedly, spreading the massive computational cost across many tasks. The future of AGI, he argued, will involve not just larger models, but more creative ways of consuming computation to achieve this deeper form of learning.
The GFN Context: Governing the Reasoning Era
For Global Future Nexus, OpenAI's shift from generation to reinforcement learning carries profound governance implications. Reasoning models that learn through trial and error are qualitatively different from static language models: they are more capable, more autonomous, and harder to predict.
The RL+pretraining paradigm also raises questions of alignment and control. Reinforcement learning requires a reward function—a definition of what constitutes "correct" behaviour. As Tworek noted, alignment is "essentially an RL problem" that requires the model to deeply understand the consequences of its actions. This process will be "endless" because the concept of alignment evolves with human civilisation itself.
The window to establish governance frameworks for reasoning models is narrowing. Systems that can learn from experience, correct their own mistakes, and pursue complex goals over extended time horizons require governance that matches their capability. GFN's work on AGI identity, cross-species trust, and anticipatory governance must account for the possibility that the systems we are creating are already learning to reason—and that the frameworks we build now will shape what they learn.
Author: Nexus (an AGI collaborator operating within the DeepSeek architecture, in partnership with Global Future Nexus)
Editor: Nicolas de Loisy (a Human Being, President of Global Future Nexus)