Hoel, E. P., Albantakis, L., & Tononi, G. (2013). Quantifying causal emergence shows that macro can beat micro. PNAS 110(49), 19790–19795. DOI 10.1073/pnas.1314922110

Key takeaways

Read in full (NOTE-726), main text only; the Supporting Information was not read.

  • EI is effectiveness times size. Effective information is the mutual information between a uniform distribution of interventions on a system’s states and the resulting next states. Divided by log₂ n it is effectiveness, which is average determinism minus average degeneracy.
  • Causal emergence is a difference in EI. CE = EI(macro) − EI(micro), and it splits exactly into a gain in effectiveness and a loss in size. The size term is always negative, so the macro wins only when coarse-graining makes the mechanism much more deterministic or much less degenerate.
  • Four constructed examples (noise, degeneracy, time, space and time) give 0.40, 0.57, 0.62 and 2.92 bits. Systems already near maximal effectiveness at the micro level cannot show emergence.
  • The macro is scored under its own uniform interventions, each macro state set by averaging over its micro realizers. The authors say this is what lets the macro win. It is a choice, and the paper does not try another.
  • Interpretation. The EI-optimal level is called intrinsic, and the macro, when it wins, is said to exclude the micro, turning Kim’s exclusion argument around. The claims about brains and the sciences are conjecture.

Why this is here

A7 and A11 cited it for when a coalition deserves a higher-level operator description. The filing’s summary was right about the result. It left out the condition that carries it, the uniform intervention distribution imposed separately at each level, and it said “causally privileged” where the paper shows only that EI is higher.

What the reading found, for the codes it was filed for:

  • QUESTION-093. EI is defined by interventions, so CE measures interventional autonomy, with predictive autonomy only for predictions from imposed states. The paper’s systems are fixed logic gates with no self-maintenance, and the coarse-graining is an analyst’s search, so the first criteria can be met with neither closure nor self-individuation. The paper’s “self-definition” is a figure of speech for the EI maximum.
  • CLAIM-154 and QUESTION-040. The same shape of trade-off, a gain against a size cost always paid, but for a known mechanism, with no data, prior or posterior. It complements the reification rule and is not a case of it. With an estimated mechanism, the maximum over many coarse-grainings would be biased upward, which is QUESTION-040’s worry, and the paper does not discuss it.
  • THEORY-133. A complement. Both reach downward exclusion system by system; degeneracy reduction is realization insensitivity in information terms. Neither paper cites the other.
  • LIT-025. A different formal object under the same name: interventional and comparing two models here, observational and asking what a macro feature predicts beyond the parts there.

THEORY-222 records the result as Proposed.