Changing ones mind later in life can be a great thing.  However the comment regarding Douglas' thesis relate to the potential for Trump style politics and policies that reflect fear of the other in Canada.  
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Douglas wrote his thesis when Jewish people fleeing Germany were refused entry to Canada.   To suggest his views weren't influential/prevalent in politics at that time is...... obtuse.
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There are many people who would welcome a Trump type politician in Canada.  Some are already trying to emulate his m.o.   It's important that Canadians do not dismiss the possibility and become complacent.