This article, Engels' Marxism, John Rees, is taken from the ISJ 65 Special Issue December 1994, pp. 47-82.The whole issue addresses Engels' ideas, and also includes:Frederick Engels: life of a revolutionary, Lindsey German, pp. 3-46;Engels and the origins of human society, Chris Harman, pp. 83-142;Engels and natural science, Paul McGarr, pp. 143-176.It's certainly worth a read, and most 'materialists' will agree with the SWP.I was a member of the SWP when it was published, but didn't have the knowledge then, to challenge the SWP's arguments.How times have changed.