Daniel if you want to get an idea of why the war started there are several recent works that explore the wars genesis. Needless to say, the jury is still out and probably no one answer or reason will ever gain consensus. The cause or causes of WWI are so complex that agreement is probably impossible because their were so many interacting factors.
To get acquainted with current thinking I would recommend the following books as a start.
Miller, Steven. Military Strategy and the Origins of the First World War
Hamilton, Richard & Herwig, Holger. Decisions for War: 1914-1917
Hermann, David. The Arming of Europe and the Making of the First World War
These books are just a start, the literature on war origination is extensive and growing all the time.