The reflective (or conscious) system drives our deliberate, analytical decisions. This is the system that is active when we take our time thinking over a decision and engage in problem solving. It’s capable of reflecting on past experiences as well as contemplating future ones.
The prefrontal cortex is more involved when this system is being used, so evolutionary speaking, this is a much more complex system than the Reactive system.
Jonathan Haidt calls this system the Rider.