There is no experience that would act as an antecedent since there is nothing like what would be encountered.
Don't be so silly. A person reacts to anything new according to the person they are (their personality), their state of mind at the time, and the exact nature of the new experience.
How did the person get to be the person they are? Well, we're into the nature versus nurture debate but we can be confident that it is
some combination, we add in the lifetime of experiences right up to the moment of some encounter with something new to get their exact state of mind and either all those possible influences mean that there can only be one reaction to the specific new experience, or not. If not, then, since we have taken into account
every possible influence, any other uncertainty must be due to nothing and therefore random.
Of course we can't predict the reaction
in practice because minds are far, far too complicated, and probably chaotic (in the
mathematical sense) but that doesn't change
the principle.
You have yet to demonstrate any of your assertions including Randomness being totally equivalent to non determined.
I've put the argument to you multiple times and you've just ignored it and keep denying I've done it. If you think the argument is wrong, tell me why. If you didn't understand it, then ask questions. Just denying that I've made a case just makes you look dim or in denial.