This is previously posted on the Ludwig von Mises forums.
It is arbitrary to label the brain as "egoistic" when the components of the brain are not. Likewise, it is absurd to label the brain as "egoistic" when composites of the "whole brain" are not.
Let us look into this. Assume that the human brain is divided into parts or modules. Each part functions independently with each other. However, they often conflict with each other.
Let us imagine a brain with three parts. One part of the brain, called area-A, deals with the maximization of pleasure. Another part of the brain, called area-B, deals with the maximization of acquiring wealth. Another part, area-C, deals with the minimization of pain.
How do they function? Area-A tries to maximize pleasure when area-C tries to minimize pain. They conflict with each other: does area-A want more pain at the tradeoff of more pleasure, or vice versa? Does area-A want desire short-term pleasure at the expense of long-term pain of area-C? How much pleasure and pain should each of these areas settle?
How does area-A and area-C resolve those conflicts? Area-A sometimes have to sacrifice pleasure for less pain in area-C. Area-C may have to increase pain threadhold for area-A to gain long-term pleasure in the future. All these actions involves area-A or area-C sacrificing with each other. Area-C may sometimes altruistically benefit area-A, and sometimes area-C may be altruistic to area-A.
Should we say that area-A and area-C behave in their own interests, or they collectively interact for the greater interest to "maximize" the "whole brain," the composite satisfaction of area-A, area-B, and area-C?
The question is that the interactions between the three components are selfish or the component parts -- areas-A, area-B, and area-C -- are each selfish but altruistic relative to the composite brain combined?
Let us look at the family.
We will use a metaphor of brain parts to represent family members. One part of the brain, called area-A, represents the mother. Another part represents, called area-B, represets the father. The third part represents, called area-C, represents the child.
The family members help each other. Each family member help one another when one is sick. Each help one another on housework. Why do all three family members help one another? Because they have an innate instinct to help each family member. Humans have evolved an instinct to help their kins. Therefore, can we describe the whole family as based on "self-interest"?
Each person is interconnected with one another in the form of an instinct to help each kin, for the greater benefit of the family. Similarly, each part of the brain conflict with each other, for the greater benefit of the aggregate brain.
Psychological egoists describe each family member as "egoistic" even when they help one another. This seems intuitively correct. However, could we say that each of the three parts of the brain are egoistic themselves, just like what each family member are?
Likewise, could we describe the aggregate "whole brain" is overall egoistic? Psychological egoists would tend to agree. But could we describe the family collectively itself as egoistic? Psychological egoists may intuitively disagree.
Each of the three brain components conflict and compromise with each other, producing an overall equilibrium. Similarly, each family member may conflict and compromise with each other, producing an overall equilibrium. Could we say that the overall equlibrium is "egoistic"? Could we say that the aggregates of the three components are as egoistic as the aggregates of the three family members?
Why do psychological egoists arbitrarily pick the brain as "egoistic," while the family member as a whole as not "egoistic"? This is very arbitrary.
One may object that the best level is to pick the individual brain, instead of groups more than one person. They claim that is is more accurate to analyze action on the individual level rather than the group level. They practice methodological individualism.
However, picking the "whole brain" as the starting point of egoism is very arbitrary. Why do psychological egoists deny that "the family as a whole" as not egoistic but assert that "the brain as a whole" as egoistic? All parts in these two interact, conflict, and compromise with each other, right?