What political concepts about Gulliver's country is master Houyhnhnm unable to understand why?

Gulliver gave a painfully detailed account of Europe to his Houyhnhnm master. This involved narration of wars, historical facts and justification of many human actions which seemed complicated as per the Houyhnhnm world view. He told his master about the Revolution under the Prince of Orange which had been going for generations, explaining the extent of the powers involved and the destruction caused as a consequence whereby a million humans were killed and hundreds of cities captured. When the master Houyhnhnms wanted to know the cause of such mass destruction, Gulliver enumerated several banal reasons which stemmed from difference of opinion. He further explained the precariousness of human nature which was never consistent with any values or principles and painted a rather dreary picture of the human society. He subtly denounced the profession of soldiers. His words were met with disbelief because the Houyhnhnm found it hard to believe that humans, who are at an anatomical disadvantage when it comes to wreaking havoc and killing, would actually be able to cause as much destruction as Gulliver described upon which Gulliver gave him a further account of the weapons used in war which caused him a lot of distress.