"The Social Revolution", 1902
Kautsky separates social revolution from revolution of the productive forces. However, in reality a social revolution and a scientific-technological revolution form one whole, as the latter forms the deeper foundation, or is the cause, of the former. Hence, if we desire to understand the deeper causes of a social revolution, we need to look at the revolution in knowledge, knowledge being today the principal productive force.
There are no "peaceful" social revolutions, as there are no "peaceful" social counterrevolutions. Kautsky pretends that there are peaceful revolutons by looking at one separate episode of, for example, the French revolution, e.g. the delegates of the Third Estate declaring themselves "The National Assembly", 17 June, 1789. However, thus he ignores the whole of the story, for this declaration has led to violent storming of the Bastille, 14 July, 1789, and other violent events that followed.
Those who pretend that there are peaceful counterrevolutions - as many say about the former USSR and Eastern Europe - ignore the mistakes of Kautsky.
Kautsky certainly represents a degradation of Marxism, as he was a heir to the writings of Engels (and hence Marx).
Marxism we see as one in a series of attempts at a unified theory and practice of knowledge, a revolutionary one at that. A decline of that knowledge, since the death of Trotsky, suggests that a new formulation of a such a theory and practice is due.