Let us assume that science links decision making to the maximization of the delivery of a particular chemical in the brain. Regardless of the decision one makes – what college to go to, whether to go on a date, whether to commit rape or refrain from committing rape, in all cases an agent performs that act that results in the maximum amount of NT is the brain.
So, does this imply that maximizing NT is the only thing in the universe that has value, and that nobody can value anything other than the maximization of NT?
The first thing that I would like to say is that I would find it highly unlikely that we are going to make this type of discovery. I would not be surprised if some values can be reduced to these types of considerations. However, I believe that hundreds of millions of years of evolution has almost certainly made the brain much more complex than this. It has an array of value systems that, sometimes, are in conflict with each other – with one system motivating P while another motivates not-P.
So, I reject that the hypothetical that a single brain state that captures all measure of value.
However, it is sometimes useful to pretend that certain options exist.
Even though we could find no examples of it among humans or other complex decision-making animals, it seems it would still have been possible for life to have evolved differently. The same chemical that serves a store for value in human cognition could, on some distant galaxy perhaps, be used to transmit pain signals to the brain, or serve some other function, where some other chemical serves as a store for value.
In which case, it would not be "maximization of NT" that has value. It would be the functional role that "maximization of NT" happens to play in human decision-making (if this hypothetical case were true, which it is not).
The idea here is that if somebody wants to reduce the notion of value to a specific mental component, that person is going to have a lot of work to do. In place of this option, I prefer a functional view of value. On this account, value plays a role in how particular intention-generating machines work. A lot of different physical things are capable of playing that role. And, as a matter of fact, in the human brain, a lot of different things probably does play that role.
We define this role using the concept of desire. Whatever instantiates the role of motivating an agent to realize a state of affairs P is captured in the concept of a desire that P.
In fact, it is quite possible that whatever instantiates a desire that P in one intentional system might be quite different to what instantiates it in a different intentional system, even though the functional state of having a "desire that P" is the same in both systems.