There were many social movements in the 19th century seeking a betterment of the working class - utopian, mutualist, religious, luddite, or even reactionary. But the Marxist brand of socialism was unique thanks to their master theory. This is what I am asking for - not a laundry list of what needs to change, no matter how justified.
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But perhaps the time for a socialist "master theory" has passed. Or, alternatively, the master theories are out there -- in either complete or nascent form -- but aren't easily recognizable as "socialist" because the old language isn't employed.
Here's your description of a sensible course of action:
A rational person in that situation [seeing problems with the real world implementation of some of Marx's ideas] would return to the drawing board, examine the past experience, get rid of what did not work or became obsolete, retained what was still usable, develop a new goal, realistically asses the chances of its implementation, and on those grounds devise a new strategy. This is what engineers do when their design malfunctions or crashes*).
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And like a good engineer who abandons a faulty design, it may be time for you to discard your dream of a new "master theory".
.d.