12.1 What is Life?

How do you know if something/someone is alive? Is there even a binary answer to it? Or do different beings have different levels of life? Depending on the nature of reality aka ontology you believe in, you may have different answers for this question and each answer has some uncomfortable implications.

Most of us would agree that a living thing is anything that has a “conscious experience”. If a robot doesn’t “sense” anything, in terms of seeing colors, hearing sound, no matter how good it is, in solving real world problems, we won’t consider it a living thing. All it does is to process bits in its hardware. A colour in a camera image it is processing is just a number it stores in the chips. This is where our inability to have direct access to the consciousness of others makes it difficult. If we did, we could use that to decide if something is alive.

Take the Chinese Room argument by John Searle. Imagine a person who knows only English sitting in a room. People outside the room insert notes written in Chinese into the room through a window. The person inside has a huge book that tells him what Chinese reply to write and send it out for each of the incoming questions. It would be impossible for the people outside to know if the person inside understands Chinese or not. Searle used this example to show that a computer program can never be “conscious” because that is pretty much what many computer programs do - Looking up answers from a database.

There are many critics who have arguments against this. One of them is that a complex AI machine does more than just passively look up data. Another response is that though the person inside does not understand Chinese, the entire room does.

Again, we run into this problem because we don’t have access to the consciousness of other beings. As we don’t have that access, we are left second-guessing whether something else is a living thing or not.

Considering these limitations, how do we define life and decide if something has life? We use some behavioural traits to determine what counts as life. For example, NASA defines life as a self-sustaining chemical system capable of Darwinian evolution. Biologists and physicists tend to have slightly different definitions depending on metabolism and other processes involved.

Most of the definitions of life are either too strict to the point that even what could potentially be living things are left out or too broad to the point where what many consider non-living are also considered living. For example, with the NASA definition, a hybrid mule isn’t a living thing because it cannot reproduce. If we create humans from labs, it would also fail the NASA test because lab grown humans won’t pass the test of Darwinian evolution. To compensate for it, if we remove both reproduction and evolutionary requirements, it creates other problems. We could argue that chemical robots are alive.

Let us look at how different philosophies define Life. Physicalism for example, would define it in terms of complexity of cells, DNA and metabolic processes. DNA is particularly interesting because the copies of DNA are made so accurately across millions of cells regularly is one thing that is not easily reproducible as a natural process and hence provides a good candidate to define life.

Physicalists disagree with each other over whether a virus is a living organism. Viruses contain DNA or RNA but they don’t have cells. If you believe that presence of cells in the body is a mandatory trait to consider anything living, then viruses or not. If you don’t think that is the case, then viruses are living things as long as they have DNA or RNA. Where you draw the line is up to you.

Where in the evolutionary chain did life really start? Again, different physicalists would draw a line at different points. Or they might say that we do not know now but we will find the answer eventually. We still haven’t understood how life started on earth. The earliest thing on earth that we know to be living organisms are bacteria which seem to have appeared on earth about 3.5 billion years while there are controversial studies showing that bacteria appeared much earlier. Considering that the earth appeared only about 4.5 billion years ago, the appearance of bacteria within a billion years seems pretty quick in the cosmic scales.

We still don’t know what really led to the creation of this bacteria. There are many theories ranging from chemical lakes to aliens dropping life here. But the question of when or how life started remains a mystery.

Going back to the question of whether life is binary or not, Douglas Hofstadter, for example, says that how conscious a living thing is, depends on the complexity of the self referential loop in its brain. He says that with evolution, the brain develops and develops the ability to see more and more of its surroundings. In this process, it eventually learns to recognise itself and develops a sense of self. Some organisms don’t have any sense of self, some have a partial sense of self while humans have a well defined sense of self. This is the result of a self referential loop in the brain.

This loop determines its sense of self and hence life itself. The implication of this approach, which he accepts honestly, is that this creates a hierarchy of life. Humans are more conscious than animals, and different animals have different levels of consciousness. The hierarchy doesn’t stop between different species. There is a hierarchy even among humans. Depending on the state of the brain, some humans would be more conscious than the other humans. Babies are less conscious than adult humans. Does this mean we should treat babies as lesser humans? The counter argument is that babies will eventually become more conscious. So we shouldn’t treat them as lesser humans now. What about adult humans who are less conscious? Are we ready to face the moral implications of this?

For a substance dualist, the answer would be that anything that has corresponding “mental substance” is a living thing. But we don’t know anything about the mental substance. How do we know if something has a mental substance or not? For all we know, some humans may not have that mental substance and are just philosophical zombies. Do animals have similar mental substance? Descartes claimed that animals don’t have any consciousness at all. If he was alive today and is on social media, he would be subject to so much abuse.

As discussed earlier, we have panpsychism on the other extreme, which claims that all physical substances have both physical and mental properties. Even the seat you are sitting on, even atoms and molecules, all have consciousness in them. Only the scales vary. Where do we even start building morals for such a philosophy?

Idealism also has issues similar to substance dualism, depending on what kind of idealism we are using. If we are using Berkeley’s idealism, one might ask which if the beings we see in the dream are real people who are part of the dream and which ones are just imaginary characters that God has added to the dream?

As you have seen so far, the answer to the What is Life question has a lot of moral implications. Different people draw a line at different points. They end up choosing veganism, vegetarianism, pescetarianism, etc. Some may draw the line wherever they want and still don’t care about eating those living things. They will justify it in their own ways.

On the other extreme, you have the Jain monks. Jainism is a religion in India that propounds that one must live a life causing the least impact on the other lives. A natural outcome of this view would be following veganism. But many strict adherents go a lot further. They even avoid eating root vegetables because it kills off the plants. You think that is shocking? Some adherents carry a broom when they are walking to gently move away insects on the floor to avoid stepping on them.

Overall, this is a philosophical question that doesn’t have a definitive answer. All of us end up writing a brute statement in our system to draw a line on what is considered life and get on with it, irrespective of whether they are consistent with the other statements in our system or not. This problem would get more interesting if aliens show up on earth one day.

12.1 What is Life?

Further Reading