Defining Life – Is it Only Physical?

This is part of a series: Define Life

As recently as 150 years ago, one of the most common scientific views of life was Vitalism. This view says that there’s something special about living things that distinguishes them from non-life, and causes them to do things and make substances that are found nowhere in nature. That “something”, they said, was its life force.

As scientists began to discover the chemical makeup of life, this view fell into disfavor. Today, if someone calls a biologist a vitalist, he usually means it as an insult.

In its place, most scientists now believe in a form of physicalism, which says that life is a machine. Furthermore, they tend to focus on the individual parts of living things much more than the whole. For example, it’s common to hear about someone discovering a gene that causes a disease or disorder, such as the most common type of mental retardation. But it’s much less common to hear about someone discovering exactly how and why that gene has its effect.

How did this happen? There were 2 main causes:

  • Scientific evidence
  • Philosophical preference

In the 1800s, scientists began to discover the chemicals that life was made of. Their single biggest discovery was that living things are made of the same stuff as everything else – they’re just organized differently. Eventually, they even started to create in labs some chemicals that had previously been found only in living things. One of the most famous examples is the creation of one of the main chemicals in urine – urea. Over time, the weight of this evidence convinced most scientists that life is a machine, rather than a manifestation of a special “life force”.

But that doesn’t explain why they focus so much on genes and individual parts, while often ignoring the big picture. This is a direct result of belief in evolution.

During the Enlightenment, many people rejected Christianity – especially intellectuals. But at first, they had no idea how to explain the existence of life without God. As physicalism became more popular, it strengthened the argument to/from design in the eyes of many, but also gave nonbelievers hope that they would one day find an explanation for the existence of life that doesn’t require a creator god.

They eventually found in evolution the core of a “creation myth” for atheists. Here was a self-organizing principle that they believed could create nearly anything, one small step at a time. It could even create life without God, or at very least improve existing life. There are, though, certain conditions that must be met for evolution to work:

  1. Living things must be able to change in a fundamental way and improve greatly, one small step at a time. There must always be a way around the steep cliffs of Richard Dawkins’ “Mount Improbable” (also known as irreducible complexity)
  2. Each small step must be a big enough improvement that the mutants out-compete the originals and become the new normal. It’s ok if a few of these steps are neutral, but the vast majority cannot.
  3. Natural selection must be effective enough that near-neutral, but slightly bad mutations don’t build up enough to cause a mutational meltdown. The slow devolution that this causes is called Muller’s Ratchet.

Because most scientists today believe that life appeared by evolution and other natural processes, they tend to try to explain everything in biology in terms of mutations or genes. After all, if we really appeared one or a few mutations at a time, the best way to understand biology is in terms of those mutations.

Scientists today, though, are discovering that life is not best described as a series of mutations, or a series of largely disconnected genes, or even as a set of haphazardly assembled genes. Instead, from the smallest protein to the largest organism, living things are best understood as a single, highly optimized machine that has many interlocking parts. This integration is so complete that one scientist said that it seems like “Everything does everything to everything“.

Therefore, life cannot appear one small step at a time. A change to most parts of the system must be accompanied by changes in several other places, or else something won’t work right anymore. As a computer geek, I’m not really surprised by this. Software engineers routinely run into the same phenomemon, although for them it’s a problem: in a large program, most pieces of code depend on several other pieces to do their jobs, and programmers have to be careful to not make the code too tangled, lest it become too complex to understand and manage. The only alternative to making complex systems so interdependent is to continually re-invent the wheel, and bloat a program with redundant code until it fills up half your hard drive.

Vitalists today tend to use this high degree of integration to argue that living things are not merely machines, but are something more. Exactly what they say that “something more” is will depend on the vitalist. Although I highly doubt that living things have something that could be properly called a “life force”, I agree that there is something more to life than just the sum of its parts.

By “more than the sum of its parts”, I mean that to fully understand one part of a living thing, you can’t just look at that part in isolation. You also need to look at the environment(s) it works in, what other parts do which other functions, etc. Also, there are emergent phenomena throughout biology.

Contrary to the beliefs of vitalists, I don’t think that these facts mean that life is not a machine. Rather, I think that some of them are inherent to complex systems, and others are good engineering. In computer networking, for instance, it’s best to set things up so no one machine has to know about the whole internet. Instead, each node just needs to know its own address or address range, and where to send stuff not addressed to itself. The effect of packets getting to the right destination could be considered an emergent phenomenon.

I also think that there is a non-physical part of living things, but it’s nothing like what vitalists believe in. I think that this non-physical part is its “software”. I put software in quotes because I doubt that each cell has a neatly separated compute module that has a computer similar to man-made ones. Instead, I expect that it’ll be extremely optimized for its environment, with the calculations and commands staying as close as practical to the sensors and servos that they use. In a different article from the one I linked to earlier, Stephen Talbott writes of proteins that act like committees, making decisions without any need for a central processor or a dedicated compute organelle. Thus it sounds to me like proteins do some kind of distributed computing.

For defining life, the takeaway is that life comes in units – whether cells, plants, animals, colonies, or whatever else. The parts aren’t alive, but the system as a whole is.

Other notes:

  1. The OEM‘s word says that we humans have a spirit:
    “For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart.”
    Hebrews 4:12 (context)

    • While I trust God’s word, I have such a vague understanding of what a spirit is that I don’t know where to start looking. I expect, though, that if I could find a correct and detailed definition of “spirit”, I’d find that it’s very different from what we usually think, and it’s been hiding in plain sight all along.
  2. If my definition of free will is correct, then the human soul is most likely one’s “whole self”, including:
    • Intellect
    • Emotions
    • Will
    • Memories
    • (possibly) Instincts

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