  We investigate the applicability of the formalism of quantum mechanics to
everyday life. It seems to be directly relevant for situations in which the
very act of coming to a conclusion or decision on one issue affects one's
confidence about conclusions or decisions on another issue. Lie algebra theory
is argued to be a very useful tool in guiding the construction of quantum
descriptions of such situations. Tests, extensions and speculative applications
and implications, including for the encoding of thoughts in neural networks,
are discussed. It is suggested that the recognition and incorporation of such
mathematical structure into machine learning and artificial intelligence might
lead to significant efficiency and generality gains in addition to ensuring
probabilistic reasoning at a fundamental level.
