This book is an attempt to compress into a small compass a discussion which would require many vol umes for its adequate treatment. It was completed in April, 1918, in the last days before a period of imprisonment. At that time few would have ven tured to prophesy that the fighting would end before the New Year. The coming of peace has made the problems of reconstruction the more urgent. The author has attempted to examine brieﬂy the growth and scope of those pro-war doctrines which aimed at fundamental economic change. These doctrines are considered first historically, then critically, and it is urged that, while none can be accepted en bloc, all have something to contribute to the picture of the future society which we should wish to create.