The question is, what do autonomy and mental sovereignty consist of when we're talking about massively genetically engineered citizens, and outright engineered minds (designed by other minds). It's a question I've been considering for a while since I switched from considering myself a hard determinist, to being a compatibilist.

I think the key differentiator for true autonomy is open ended psychological flexibility. That is, sufficient deliberative control over our own mental processes and decision making faculties to be able to adapt them to whatever experiences we have, and whatever circumstances we find ourselves in.

We are introspective beings able to inspect our own mental processes, consider our own motivations, priorities and beliefs, and adapt these based on new experiences. On the one hand this means we are very largely shaped by our experiences of the world, on the other hand it means we are not completely locked into the same limited set of behaviours and responses regardless of what experiences we have, and therefore what we learn. I think that our basic biology and psychology do limit this flexibility in important ways, but I do believe that we've just about reached the level where we are in principle capable of open ended mental flexibility.

If the Culture has a similar understanding of mental autonomy, that means that they could consider Culture citizens autonomous while also recognising that the vast majority of them would in fact remain completely satisfied with life in the Culture. In fact, in principle engineering Culture citizens in that way would be an ethical thing to do, because they would in principle still have the ability to adapt in terms of their beliefs and goals in response to changes in circumstances.

Likewise with Minds. A major difference being that the Minds can anticipate most of the experiences average citizens will have within the Culture and how they would behave, whereas Minds have much more varied experiences and much more capable mental resources, and therefore the ability to anticipate their likely resulting opinions, beliefs and behaviours would be much more limited.