What is a System One model?
Daniel Kahneman described two modes of thought in Thinking, Fast and Slow:
System 1 (fast) — automatic, intuitive, milliseconds.
System 2 (slow) — deliberative, effortful, seconds to minutes.
Applied to AI
| Traditional LLMs | Decision Models (System One) | |
|---|---|---|
| Analogy | System 2 | System 1 |
| Output | Free text, token by token | Typed decision + probability |
| Typical time | 1–30s | 70–500ms |
| Strength | Reasoning, generation | Classification, routing, scoring, guardrails |
The category opened with Jev (TypeSafe AI, ). Open peers now also appear on the catalog and quadrant. This article explains the category, not just one product.
FAQ
Is a System One model the same as an SLM?
No. SLMs still generate text; Decision Models only return typed decisions.
Do they never make mistakes?
They can pick the wrong option. The typical claim is they cannot invent outside the schema.
Do they replace ChatGPT?
No. They complement LLMs — System One decides fast; System Two reasons when needed.