  A recent paper by Souza, Oliveira and Sarthour (SOS) reports the experimental
violation of a Leggett-Garg inequality (sometimes referred to as a temporal
Bell inequality). The inequality tests for quantum mechanical superposition: if
the inequality is violated, the dynamics cannot be explained by a large class
of classical theories under the heading of macrorealism. Experimental tests of
the LG inequality are beset by the difficulty of performing the necessary
so-called 'non-invasive' measurements (which for the macrorealist will extract
information from a system of interest without disturbing it). SOS argue that
they nevertheless achieve this difficult goal by putting the system in a
maximally mixed state. The system then allegedly undergoes no perturbation
during their experiment. Unfortunately the method is ultimately unconvincing to
a skeptical macrorealist, and so the conclusions drawn by SOS are unjustified.
