Question

What were the main causes of World War I?

Answer 1

slavery

Answer 2

Two acronyms may help:MAIN outlines the general causes of the Great War in Europe, while a slightly "off color" mnemonic device, SLUTZ, outlines the reasons for US entry into the war. The two devices, taken together, can also help you remember the most important of Wilson's 14 points. Here goes:
M-militarism--the buildup of large armies and modern weaponry in a kind of arms race. wilson attempted arms control in the 14 points
A--Alliances: secret alliances between the coutnries of Europe "Dominoed" Europe into war. Wilson also attempted to use the League of Nations to keep alliance agreeements out in the open so no one would be blindsided by secret alliances again.
I-Imperialism--Germany, as the new kid on the European block, wanted a share of teh Asian and African colonies that older countries took for granted. wilson specifically addressed this in his 14 points with a big emphasis on "Self-determinatio" for all countries
N-nationalism the feeling that your country is superior and always right, and a desire to use all those big bad weapons referenced above. The League of Nations was an attempt to tone down nationalism.

for the other, American reasons
S-the sussex pledge, promised and subsequently broken by Germany with its U-boats
L-the sinking of the Lusitania
U=unrestricted submarine warfare
T Ties, mostly JP Morgan and mostly financial, and cultural ties with Great Britain
Z-the Zimmerman telegram that unveiled the German attempt to lure Mexico into an alliance that would be beneficial to them both.

Answer 3

Disparities and conflicts of interest.