the math object
What a Jacobian actually is
The ordinary derivative — “nudge the input, watch the output move” — grown up to handle vectors in and vectors out. With a live tangent-line you can drag.
the instrument
Why “transport a hidden activation into the final-layer basis via J”
Point the Jacobian from mid-stack to the model’s exit and it becomes a lens — a readout of what a buried thought is disposed to make the model say. Click down the layers and watch a thought resolve into words.
the claim
The four tests that make it a “workspace”
Verbal report, directed modulation, internal reasoning, flexible generalization — the criteria that promote “the lens finds verbalizable representations” into “these form a global workspace.” And then: could a beauty axis live there?
the destination — the paper
Verbalizable Representations Form a Global Workspace in Language Models
A new interpretability method (the Jacobian lens) surfaces a small, privileged set of “word-like” representations that the model can report on, steer, and reason with — structurally like the global workspace of consciousness theory. Once the trail is behind you, the paper reads like a home you already know.