Nathan Lambert: Closed Models Will Take 'Significant Leaps in Directions Unlikely for Open Models to Follow' in 2026

Interconnects·medium signal

Allen Institute's Nathan Lambert (Olmo post-training lead) published an Interconnects essay arguing that through 2026, closed models will diverge sharply from open models in capability — taking leaps that open-weight alternatives can't follow due to compute, data, and RLHF infrastructure gaps. He argues this means open models 'need to be considered, funded, used, and discussed differently' going forward. For builders choosing between open and closed models: Lambert is signaling that the gap may widen, not close, and that open-model strategies need to be designed around complementary strengths rather than parity.