I suppose one of the main reasons I like this book is because it supports one of my main theories about life: we evolved the capacity for self-awareness and abstract thought by accident of history, and there is therefore no reason to expect happiness, satisfaction, justice, or any other moral, emotional, or complex good to be achievable or maintainable in our lives, let alone in society as a whole. (Summarized as briefly as I could).
So one of Hayek's main contentions is that: achieving many things that are widely desirable - peace, safety, availability of food, health care, shelter, etc for large numbers of people, in short, a stable society - cannot really be brought about without circumventing many of our strong natural urges and instincts. Them's just the breaks, and thus there is some inherent conflict between our everyday, moment-to-moment, personal desires and actions, and that which apply to society at large, or as Hayek calls it, the extended order.
This speaks to me particularly, due to my recent descent into a standard working life and the accompanying lifestyle, which has only served to enhance my previously held interest in maybe running away to live in the mountains, eventually forgetting language, tool-use, and tact. But instantly upon feeling this impulse, I fall in the hole of how is this sustainable, not everyone can have free range in the wilderness, also medicine and the internet. So for all the hollowness and distress and anxiety of civilization, it's gotten to where it is because it works.
The titular conceit is that we are clever enough to design, from scratch, from our own brains, a superior system to those that evolve. Sure, we're quite clever. We've got some science here. We can perceive how things work, make predictions, figure out and engineer some pretty complex stuff. But in systems as enormously complex and chaotic as an entire civilization, with billions of agents contributing to its behavior, let alone non-agenty factors, it's just not practical to think that we can sit down and work it all out.
Part of this is something I become more and more aware of in myself. Putting aside worries that it means I'm inferior, let's say it's perfectly normal and acceptable: my ability to reason things through, abstractly, is all but pathetic. My recall may as well not exist. But my recognition and response are actually pretty ok. Once I start poking around in a system, trying things out, then I can find where all the pieces are, then I can start to gather information and get an idea of how it's going to act. But I have to try it out. And even once I'm familiar with a system - even something as completely simple and controllable as my company's code base - I still can't foresee every possible implication of a given action. There's too many steps, too many layers, between one change here and what relies on it. Maybe there's an obscure trick of implementation in some third-party software, maybe it's details of the system I just wasn't aware of, maybe it's something I built myself that I've just forgotten about.
And of course this doesn't show that nobody can be much better about this than I - of course many people can do better, remember and predict better, understand more complex systems. I'm obviously not the measuring stick to use for humanity here. But there may be something to the general observation that not all information is or can be stored in one place, either in a single person's head, or even among a team of people.
And so, what Hayek drills into us repeatedly in this book, is that the way that information gets communicated is the market. Yes, there are things about it that grate against our sensibilities. Yes, there are pernicious side effects. But it works - you can't expect any one person, group, organization, or institution, to be able to design and coordinate a system as complex as a civilization or economy. In order to know what actions are best taken, there needs to be information exchange, and that information just can't all be available in a timely and accurate manner to a central body. Different people have different perspectives, different expertise, different things they'll remember or focus on. Sometimes there's relevant information that they don't realize is relevant until it comes up - they recognize its import but didn't recall it until prodded. And that's not good enough for the level of organization needed to support the number of people needed to provide the variation needed to allow for specialization, improvement, and the increase in things that most people probably want - peace, stability, food, etc.
Hayek does make a lot of claims about what is and is not possible, without really providing solid evidence to support these claims, but he bring up many solid points that are worth chewing on, to figure out exactly why or why not they are correct. And he definitely gained my respect and willingness to hear him out by his focus on actual effects and knowledge, and his eschewing of the temptation to rationalize choices and actions, as exemplified by this quote:
"Virtually all the benefits of our civilization, and indeed our very existence, rest, I believe, on our continuing willingness to shoulder the burden of tradition. These benefits in no way 'justify' the burden. But the alternative is poverty and famine."