Anarchy and Order. From Chaos to Cosmos and vice versa - Concealed by sophisticated Greek words, the classical topos of International Relations theory is back: chaos is in fact considered the consequence of a « natural » condition of anarchy experienced by states. The whole issue may be translated in a research criterion: anarchy or chaos (in the title) would make useless a reflection on war (bellum omnium contro omnes escapes judgement), a topic which was addressed by many and very important ancient philosophers and historians. The proposal put forward by the author is to consider chaos and cosmos as quantities that can mix and get together, and/or that can inversely increase or decrease being linked. The conclusion will be in form of a question: is cosmos diminishing so that we have to hypothesize that chaos will increase?