With the article the preceding an adjective, the resulted phrase is usually treated as a plural noun. Examples are "the poor", "the free", "the brave", "the wise", etc..
It seems that the phrase "the left" or "the Left" (when it refers to political groups) is an exception. Sometimes it is followed by singular verbs, sometimes it is followed by plural verbs. My question is:
What is so special about the phrase "the left"? When it is used as a singular noun, does it somehow convey a subtly different meaning than it being used as a plural noun?