This is a Good question. You often hear about Scientific Socialism and the Dialectical Method. Basically socialism is the answer to the historical development that we’ve seen throughout society. Once you understand DialMat, you see the way that things develop and grow and decay. Einstein himself wrote in his “Why Socialism” that politics, like astronomy, like biology, seek to find universal rules within their field of study and apply them to better understand how these fields develop and why they do. Scientists, political or otherwise, also seek to find trends and different stratas within their field and see what grows and what decays. We as socialists view the changes and repudiate the decay, the stagnant and dying, and we uphold the progressive, the rising, the correct next development. That’s why we repudiate Capitalism, Imperialist conquest, outdated social concepts of hierarchy, etc. When socialism is not scientific, it doesn’t look into the trends and changes or if it does, it doesn’t care about responding. A type of Socialism that Marx and Engels shat upon was Feudal Socialism, a version where upon defeating the capitalist class, the proletariat and peasants all fall into peasantry rather than Proletarianization, which is necessary for socialist transition. The peasants, using hand labor and simple looms and handcrafts cannot compete with production that works in concert with each other with socialization of labor, a positive thing that capitalism calls forth as opposed to the Feudal style of production. Because we need to remember that capitalism was once Revolutionary back in its day, there are aspects which are better than the era preceding it. So Marx and Engels said that essentially you can’t go backwards with Historical Materialism, otherwise your supposed socialism is actually reactionary and doomed to fail. Scientific socialism, Marxism-Leninism is scientific because of the way that it analyzes the world and fights for the Revolutionary ideal of the international proletariat. The scientific part makes sense because think about this: China wants to make sure every hospital has enough equipment, to do this, questions will need to be asked, people will describe what they need, where it’s going, etc. The science that is occurring is in the process of data collection and deciding what to do with that data. Scientific Socialism is a part of Planning Economies so you don’t have to worry about the vagaries of private capital and Free Markets If China or Vietnam or DPRK was Reactionary and didn’t support scientific achievement in their countries and didn’t move past basic production, none of them would be where they are today, or even exist as nations. That’s the basics of Scientific Socialism, more can be explained by Engels in “Socialism Utopian and Scientific” and Stalin’s “Anarchism or Socialism”