  We introduce a model of classical and quantum observation based on
contextuality and dynamically evolving apparatus. Power sets of classical bits
model the four classical states of elementary detectors, viz. the two normal
yes/no signal states, the faulty or decommissioned state and the non-existence
state. Operators over power set registers are used to describe various physical
scenarios such as the construction and decommissioning of physical devices in
otherwise empty laboratories, the dynamics of signal states over those
detectors, the extraction of information from those states, and multiple
observers. We apply our quantum formalism to the Elitzur-Vaidman bomb-tester
experiment and the Hardy paradox experiment.
