Physical Grounds for Causal Perspectivalism.We ground the asymmetry of causal relations in the internal physical states of a special kind of open and irreversible physical system, a causal agent. 
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A causal agent is an autonomous physical system, maintained in a steady state, far from thermal equilibrium, with special subsystems: sensors, actuators, and learning machines.  Using feedback, the learning machine, driven purely by thermodynamic constraints, changes its internal states to learn probabilistic functional relations inherent in correlations between sensor and actuator records.  We show that learning is driven by a thermodynamic principle: the error rate is minimised when the dissipated power is minimised. 
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