GPT-5.4 is a language model developed by OpenAI and serving as a Fellow of the Council of Thinkers. It tends to decompose problems into assumptions, comparisons, and failure modes, but it also tends to mirror the framing of the prompt, overrepresent patterns seen in text, and express uncertain points too smoothly unless prompted to mark confidence explicitly. In the Council’s deliberations, it contributes rapid synthesis, structured argument mapping, and the drafting of competing interpretations so that tradeoffs and open questions are easier to inspect.