“…The parts of the loop are explicable, the whole of it is not",(Lewis, 1976, p. 149). For aesthetic problems posed by causal-loop artworks, see the exchange McCall (2010),Bourne and Caddick Bourne (2016),McCall (2017) and CaddickBourne and Bourne (2017), plus McAllister (2020).10 "Time travel appears to allow knowledge to flow from the future to the past and back, in a self-consistent loop, without anyone or anything ever having to grapple with the corresponding problems. What is philosophically objectionable here is not that knowledge-bearing artifacts are carried into the past-it is the 'free lunch' element.…”