Then you have your modern brain. It has a suite of cognitive superpowers that are collectively referred to as executive function.
With executive function you can weigh options and look at a problem from different angles. You can consider past experiences and gaze into the future. It is this area of the brain that you use to plan and reflect.
Other species don’t have much in the way of executive function.
Your dog would have difficulty going through a pros and cons list. If you point at an interesting cloud formation and say “Look at the clouds, Ralph,” your dog will sniff your finger—even if his name isn’t Ralph.
On the other hand, dogs are not judgmental or manipulative; you don’t need executive function to be a good soul.
And as powerful as your modern brain is, it does have its limitations.
Your modern brain is an energy hog. It can be lazy and easily distracted, and it doesn’t always follow through on intentions. It also has an annoying habit of tapping out when feeling a little tired or grumpy.
Your ancient and modern brains live together within the same skull, yet they are eons apart on an evolutionary timescale—and each has its own agenda when it comes to your behavior.
