I cannot describe my points in unambiguous text so I am forced to give a few examples to illustrate my point:
Natural Law and Human Nature
Sea-Creatures
Assume that the typical human looks like some type of intelligent sea-creature living in the water. They are intelligent, capable of reading the minds with each other one thousand miles away. They display much empathy, compassion, and benevolence. Evolution has selected them to help one another in case of danger. If one sea-creature senses danger, it sends out messages to all the sea-creatures within a thousand degree radius. Receivers of those messages would immediately rush to the location, detecting any predators, to save the endangered creature.
One day, one sea-creature, called Chris, thought of a malicious idea. He was born with a talent to deceive messages, to lie to other sea-creatures. He soon found that he is able to send false calls of danger to others, in order to scare them. Chris will “cry wolf” to manipulate other sea-creatures to perform chores that he dislike to do. Some of these creatures will die of the exhaustion in attempt to help Chris.
By libertarian standards, Chris is acting immorally. He deceived other sea-creatures to perform his duty under the guise of the presence of danger. It is fraudulent, and equivalent to enslaving others.
Libertarians usually support some rights such as defamation, libel, and slander. Should the sea-creature society legalize the freedom of speech, it would allow Chris to be dishonest to exhaust the sea-creatures to extinction.
In addition, the female sea-creatures get highly traumatized by voyeurism. If a female sea-creature finds out that a nearby voyeur had spied her having sex, then she will acquire post-traumatic stress disorder. Every night, she will have nightmares from knowing that some other male has spying her having sex. All of the females will go traumatized throughout life.
However, libertarians usually support the legalization of voyeurism. This shows evidence that ethics depend of biology, as some laws can apply to humans but not to animals.
Monster
Imagine a enormous super-creature, shaped like a octopus, with one million tentacles. It roams about the earth, and weighs one billion kilograms. Within each tentacle, there exists a brain at its tip. Each brain is capable of rational foresight, empathy for other tentacles. Each tentacle is autonomous, can move in its own direction, and can move above and below each other. Occasionally, a new tentacle is created, old ones die and falls off. Each tentacle drills beneath the earth, looking for minerals to eat, and water to drink.
However, some tentacles eventually found out that it can be more efficient by specializing its labor. Instead of every tentacle drilling beneath one part of the earth for water, and minerals, they discovered that each could divide those tasks.
Now, some tentacles, who are strong and sturdy, can dig up gold to consume. Some tentacles, who are narrow enough, can pierce through the earth, through the hard rock, for groundwater. Some tentacles, who are created with a heat-resistant cover, can resist heat up to a million degrees Celsius. They dig through the hot molten mantle through earth, absorbing great amounts of heat to prepare for winter.
Each specialize with their own job. They exchange with each other. The gold-digging tentacles exchange for groundwater dug up from the water-digging tentacles. The heat-adsorbing tentacles exchange water from the narrow-welldiggers to rehydrate themselves.
However, the super-creature can only survive if exactly one third dug gold, exactly one-third dug water, and exactly one third absorb heat. It is programmed to be that way. If slightly one more or one less of the tentacles dug gold, then the whole super-creature will collapse, due to disequilibrium.
Therefore, newly born tentacles are assigned to a job.
In the libertarian viewpoint, this violates voluntary association, because it forbids each tentacle to choose their job. However, because forbidding the freedom to jobs is necessary for the tentacle to survive, the each tentacle should not have this right.
Its tentacles has mysterious dynamics. Besides the brain, a mouth is also located at the tip of each tentacle. Each tentacle must eat a balanced meal of gold and water every day. However, the gold and water will eventually flow from the tip of each tentacle to the central body of the super-creature, where the tentacles meet. If a tentacle each too much and turns fat, the nutrients will flow faster to the central body. Those excess nutrients get redistributed to other smaller tentacles.
The redistribution of nutrients happens constantly. The more productive tentacles will get upset for redistributing their nutrients to the poorer ones. And the less productive tentacles are happy that they receive free nutrients from the more productive tentacles.
This redistribution of nutrients functions like a welfare program. The more productive tentacles are being “taxed” to support the poorer tentacles.
At this point, the distinction of positive and negative liberty collapses. Because “negative liberty” is freedom from interference, each and every tentacle lacks negative liberty because of the nutrient-redistribution program.
Ghost-Creatures
Imagine some creatures who can travel through each other without interference. Therefore, it is unreasonable to forbid trespass and aggression, because nobody will get interfered or get hurt.
However, humans must ban trespass and aggression because of their biological trait that disallows the same organism to stand on the same location on the same time. Therefore, trespass and aggression are ad hoc rules that applies to humans but not to ghost-creatures.
Conclusion
These three examples demonstrate that ethics depends on the morphology of animals.
Flaws of Psychological Egoism
Below we will discuss four flaws of psychological egoism.
First Flaw
The first flaw of psychological egoism is that it does not accurately describe all human action. Reflexes are not based on pleasure and pain.
Second Flaw
The second flaw of psychological egoism is that 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?
Third Flaw
A third flaw of psychological egoism is that decisions made by the brain are not necessarily ‘optimal’ to maximize pleasure or to allievate uneasiness. Preference can change, and it is difficult to keep track of different preference changes developed throughout life.
For instance, an eight-year-old schoolboy, called Bob, may decided to assault his classmates for fun. Turning about 13 years old, he sexually matures and becomes sexually obsessed in girls. However, no girls at his school will be romantically interested in him, because of his poor reputation during his childhood. Bob regrets that he had ruined his reputation during his childhood. He wished that he had not assaulted his classmates when he was eight years old. Bob feels upset because he could not change that.
Let us say that Bob does not know that he will have a obsession for girls when he turns thirteen. Therefore, Bob, when he is eight-year-old, does not know that assaulting his classmates will lead to bad consequences for the rest of his life. Because he lacks the knowledge that he would have a preference for girls later in his life, he did not “maximize” that.
The Bob example has proven that humans cannot accurately adjust to dynamic preferences.
Fourth Flaw
Humans have cognitive biases that simply cannot “optimize” pleasure. Imagine that you are preparing to go to an airport to go on a trip. However, humans decide to arrive an hour early on the airport because they are biased to reduce risk. Even though they can arrive merely five minutes earlier, they decide to miss fifty-five minutes of pleasure.
People that have obsessive-compulsive disorder do repetitive stuff. They simply do not “maximize” pleasure.