I always thought Mentats were a reference to (and an extension of) the original Computers - humans that performed calculations in their head.
> The term "computer", in use from the early 17th century (the first known written reference dates from 1613),[1] meant "one who computes": a person performing mathematical calculations, before electronic computers became commercially available.
They were. Same with the Guild Navigators. Humans replaced the thinking machines following the Butlerian Jihad, taking back agency for humanity, but sacrificing agency for those individuals who became machines themselves.
It think this is an oversimplification. Mentats still had agency--both Piter de Vries and Thufir Hawat have their mentat schemes to kill the Baron Harkonnen.
One of the big points of the Dune series is the indeterminacy of the universe. Computers, being deterministic, couldn't think properly to handle the full universe, so humanity's subjugation to computers (i.e., "machine thinking", both as rule by computer and as habits of thought for humans) was a dead end. Dependency on computers also meant people didn't develop human skills.
After the Butlerian Jihad, the Guild, the Mentats, and the Bene Gesserit all became schools of human development. Mentats aren't just human computers who perform calculations quickly. They cultivate almost zen-like mental states that allow them to sift patterns of data into conclusions, among other techniques. The later books go into much more detail, but part of the point is that they're not deterministic thinkers; they're practitioners of very advanced modes of consciousness.
Most people in the Dune universe are literally vassals of feudal lords. By removing advanced machines, they instead have warped, specialised human beings in the machine's functions: mentats, suk doctors, navigators, etc. They are servants, human cogs in the system. It's dystopian.
That's it. I played Dune 2 and watched the movie so much I thought I knew most about the universe. I guess its about time I pick up Herbert's seminal work. Thanks for your analysis here.
> The term "computer", in use from the early 17th century (the first known written reference dates from 1613),[1] meant "one who computes": a person performing mathematical calculations, before electronic computers became commercially available.