(i) Letters To Malcolm is a series of fictional letters, thus a work of fiction. Fictional events concerning Malcolm's family occur in the background.
(ii) Lewis discusses philosophical and cosmological issues.
(iii) He speculates about bodily resurrection and Heaven, thus connecting with several works of fantasy by American sf writers. See here and here.
(iv) This is the same CS Lewis who, as first person narrator, is a minor character in the Ransom Trilogy, which is his reply to the major science fiction works of HG Wells and Olaf Stapledon.
(v) Poul Anderson is a Wellsian and Stapledonian sf writer whereas Lewis is both anti-Wellsian and anti-Stapledonian.
(vi) We need to read both sides of the argument, especially since both sides are written well. Lewis and Anderson share the ability to present sympathetic treatments of characters with whom they disagree morally and philosophically.
