Thinking introduces the mathematically unpredictable. Maybe you believe in Hari Seldon
of the Foundation books by Asimov, but even Seldon
did not claim certain determinism.
For example of what mind can do:
There are software programs which can
toss you to a randomly-selected site in the
world wide web, usually by your own choice and
"click." If the site is interesting enough,
you might make a change in life, affecting others
in a cascade, all stemming from a random occurrance.
Mechanics cannot predict that much.
The mind's reflective capabilities, times quality of information, times physiological inputs, can all equal a prediction which will be right some percent of the instances. But people resist being too predictable and will catch on to being
manipulated, usually. They will behave contrarily,
thus reducing predictive power of any model being used against them. So dictators have trouble using this knowledge for evil