Having been a member of the Dutch social-democratic party with Marxist tendencies when I was in my twenties, of course I should have read this book at that time. It was mentioned a lot at that time, but always with a certain disdain. But actually it is well informed, well written and raises important issues.
Already in 1947 it gives a lot of facts about the Soviet Union that makes it very clear that it in no way can be understood as a socialist state or even a state that is striving to become one. Rather, under Stalin it was reformed back to a Tsarist - but now totalitarian - regime. Koestler paints a very specific picture about changes in the law and assigning state heroes from the old regime that leave no doubt about how Stalin saw himself. Even now worth the read I think.
Still, Koestler defines himself as a socialist at that time. In his analysis about what went wrong and how to escape, he points to the ethics of the Commissar as against that of the Yogi. Ethics has been reduced to psychology (Freud - Superego), physiology, self-interest etc. This leads of course to cynicism and a practice where attaining a goal justifies the use of any means. It leads to the power politics of the Commissar.
Using insights from science about the irreducibility of complex phenomena to `lower' levels - insights that are broadly in line with contemporary ideas about it -, Koestler argues for the irreducibility of ethics as an experience of human beings in society.
Now, whereas normally our practices are done in a specific level of complexity, Koestler sees the Yogi as looking `sideways' at these levels and thus having a broad view of reality. Koestler argues that such a view is needed to transcend being stuck in the view of the Commissar and in power politics.
Although not very convincing in it self, Koestler's Commissar / Yogi view points to difficulties in ethical practices in modern society that are very real. In this sense this part of the book is a forerunner of Peter Sloterdijk's Critic of Cynical Reason. The problems can be summed up as the decline of `good will' under the force of circumstance; everyone really wants to act ethically correct, but the force of circumstance dictates otherwise.
Said differently, we are trapped in subsystems for which ethics is not a meaningful way of communication. We have to act according to the practices of the subsystem or radically step out of it (unthinkable). We don't want to pollute the environment, but we need a car to get to work. Our company wants to use non-slave-produced materials, but it has to compete with other companies in the field. The commissar does not want to chop off heads, but the damned capitalists are after his throat.
All in all this book is a better read for its facts and the questions that it raises, than for its analysis of them.
So, would you use power politics if your life is in danger?