  Inspired by the swarming or flocking of animal systems we study groups of
agents moving in unbounded 2D space. Individual trajectories derive from a
``bottom-up'' principle: individuals reorient to maximise their future path
entropy over environmental states. This can be seen as a proxy for keeping
options open, a principle that may confer evolutionary fitness in an uncertain
world. We find an ordered (co-aligned) state naturally emerges, as well as
disordered states or rotating clusters; similar phenotypes are observed in
birds, insects and fish, respectively. The ordered state exhibits an
order-disorder transition under two forms of noise: (i) standard additive
orientational noise, applied to the post-decision orientations (ii)
``cognitive'' noise, overlaid onto each individual's model of the future paths
of other agents. Unusually, the order increases at low noise, before later
decreasing through the order-disorder transition as the noise increases
further.
