A fetus at around 6 months, yes.

The argument against that would be that the value is on the capacity of consciousness and that sleeping people can be brought back to a state of consciousness. But yeah, we could debate this for hours.

First, that was a pretty amusing story, so thank you for taking the time to write that.

I'll just say these few things:

In the case of the guy in your story, he certainly is an anomaly. The doctor probably mislabeled him as brain-dead. People who are descriptively brain-dead, by definition, can't come back to consciousness. Without the brain being able to be supplied with blood and oxygen, the rest of the body just can't work.

>So even with a fetus we just don't know enough about the brain to be 100% on consciousness or lack of if that's what you are getting at.

This is where I was getting at. Consciousness/sentience seems to be the foundation for how we value humans. We may not have perfect knowledge of the brain, but we do know quite a bit. A priori wise, we can deduce that zygotes probably don't have brains and 8 month old fetuses probably do. Furthermore, there is solid scientific evidence that the brain develops the capacity for consciousness at around 6 months.

>If we grew brainless humans in labs for donor organs, kept alive just to take parts from as they live alone in a tube people would be outraged and sickened, even without a brain.

I can understand that people would be sickened/outraged by this thought experiment. However, arguably moral conclusions shouldn't stem directly from our intuition about things. In the past, many people intuitively thought slavery was acceptable, but those intuitions don't justify the conclusion.

Do you value a brain-dead human on ventilation the same way you value a teenager?

Many people attribute sentimental value to a corpse, but not moral value. Most societies don't give corpses moral rights the same way moral rights are given to people.

The broader point I am making is that when you say you value "life", I don't think you really value a thing that is biologically living. Because if you really did value "life" for personhood, you would apply it to a corpse that still has living biological functions. However (correct me if I'm wrong), your reply implied that you don't value corpses. If that's the case, why do you value the living biological functions of fetuses and teenagers, but not the living biological functions of corpses?

A human corpse can have living and working biological functions. Would you attribute moral consideration to a corpse?