What Is the human?

Key idea:
Being human is primarily determined by cognitive capacity and the brain, more than by the physical body.

As described above, the human consists of various organs, systems, and limbs. If one organ is removed, does that person remain the same, or do they become a slightly different person? How do we determine what a person is, and what defines being human? Is it determined by behavior or by appearance?

If a person receives an artificial hip, does that change them as a person? If he is known as an Olympic athlete, then it indeed changes his performance as an athlete, but do we then consider him to have changed as a human being? The same applies when the heart is replaced, and so on. How many body parts and organs can be replaced before someone is no longer the same person? If something in the brain is altered through surgery or otherwise, this generally seems to result in a much greater change in the person. It therefore remains dependent on what one considers the defining factor of that person.

A major distinction between animals and humans is generally seen in the way humans use their brains. Through the use of the brain, humans can think about the future and the past, they can calculate and write, and they can communicate with others in understandable sounds. In most of these abilities, humans are more capable than other animals. All these abilities are primarily directed by the brain and are then carried out with the help of various organs: arms, hands, voice, eyes, and so on.

The major distinction manifests itself through:

• abstract thinking
• language
• reflection
• planning

As an example, we can look at Stephen Hawking, the British physicist, who developed amyotrophic lateral sclerosis (ALS), which left almost his entire body paralyzed, except for his cognitive capacity. In this case, Hawking was still considered the same person as before the illness, except for the physical characteristics. Is this because the defining factor for Hawking was his cognitive ability?

Would it have been different for Usain Bolt, the Jamaican sprinter, if his cognitive capacity had declined to a low level while his sprinting performance remained unchanged?

All things considered, a person as a human being appears to be determined primarily by the brain. Or as the title of Swaab’s book states: “we are our brain.”

When we consider it this way, an anecdote comes to mind, told by a philosopher, which goes as follows:

An elderly man, whose body has weakened to the point that he does not have long to live, but whose cognitive capacity remains excellent, has a conversation with a young athletic man. He says to the young man:

“I do not have long to live, but you are still young, handsome, athletic, and have your whole life ahead of you. You are almost perfect, but the only drawback is that your cognitive ability, which you were born with and is entirely beyond your control, is not very strong. Since I am at the end of my life, I no longer have much use for my brain, and therefore I offer to have my brain transplanted into your head and yours into mine. Your quality of life would increase significantly, and for me it no longer matters.”

What the young man replied is not known, but it is an interesting thought experiment (Einstein: “Gedankenexperiment”) that raises intriguing questions:

• Where does identity reside?
• What makes someone “themselves”?

And perhaps even more fundamentally: what does it mean that this person, however defined, is ultimately mortal?