So let's look at the premises that underlie what you claim is a flawed conclusion. Basically:
Originally Posted by lakers4sho
1. When two atoms interact under the exact same conditions, they necessarily interact in the same way.
2. If 1, then they predictably interact in that same way.
3. If 2, then given a sufficiently detailed set of initial conditions and a set of known rules (and boundless analytical power), it is possible to infallibly predict what interactions will take place in advance of them taking place.
3b. If 3, then once those interactions take place, another set of conditions is generated, and from that set of conditions, another infallible prediction can be made -- this can continue ad infinitum.
4. If all future interactions can (theoretically) be infallibly predicted, they are predestined. That is, what happens is the only thing that could have happened.
Now, again, I don't necessarily buy the whole argument, but I do think this is along the lines Harris is thinking. His explanation of it is a whole lot more developed than mine, but that's the gist of it.
“If we sacrifice our values because we’re afraid, we don’t care about those values very much" -- Edward Snowden