Very often I hear that social democracies particularly in Europe have only risen due to the bourgeoisie's looming fear that if they hadn't implemented a few programs or policies to appease the working class peoples there would have been a communist revolution.

Now, this does sound like common sense. But is there any particular source that gives evidence to this claim? I'd rather be able to take a strong stance with this opinion by being able to cite sources instead of my friends' opinions.

https://docs.google.com/forms/d/e/1FAIpQLSeUdBZcLtKsBOki4Dg38pjPr721rNKAyHJib0LY3FBPd13yRg/viewform