The impossibility of immortality.

Defining Immortality

A person who lives forever is immortal. This requires two things:

1. That they live.
2. That they continue to do so for an infinite period of time.

Let's deal with 1 first. Here's why defining living is important.  Let's say someone is cryogenically frozen and kept in stasis for the next 1000 years. When they wake up, have they lived 1000 years? If we freeze someone in the depths of space, does the fact that they could plausibly be revived in a trillion years mean they are effectively immortal? I'd say no. Suspended animation, keeping a person in a state where they are not running (people are software), does not qualify as being alive*. X years in stasis does not mean that you have 'lived' X years. Why? Because a person in stasis does not think, and a person who does not have conscious thoughts is not alive**&*. Living is consciousness, and immortality requires a person to exist and be conscious, even if that consciousness is interrupted by stasis.

Why is immortality impossible?

As a person lives, they change. Our experiences shape us and change us. They change us in the short term, making us feel and think differently but they also shape us in the long run, changing our beliefs and values, our behaviour and our hopes and dreams. And therein lies the rub. Immortality implies infinite experience. No matter how minuscule the change each new experience effects, a positive amount times infinity is infinite. After enough time passes in an physically immortal beings life, it is invariably no longer the same person. Thus, the person it once was no longer exists and has died.

Objections:

First, let's deal with internal objections, that is those which operate within my paradigm and do not challenge my definitions of personhood and/or life.

Experiences effect us less and less as we age.

The argument is that not all experiences change us. When we are born our early life experiences, how we are raised, what culture we are steeped in, may indeed shape us greatly but later experiences shape us less and less. (insert example here). Hence, if we were to live forever, our character would solidify until, at a certain point, we are not longer changed by our environment.

The problem with this objection is fairly simple. If it is the case that the amount by which new experiences shift our character, while eventually falling to very low levels, remains positive, then over an infinite length of time those experiences will still change us into a different people. If it is the case that new experiences cease to have any effect on us whatsoever, then at that point we are effectively dead anyway. We've calcified into a fixed state incapable of change. Just like a person kept in stasis, we are not dead but neither are we alive. (reword. weak argumentation)

Experience does not change "core" traits, only peripheral ones.

This is a strong objection. It goes like this. Not all our traits define us equally. Some, like our fundamental values, baseline behaviours and personality traits define us a great deal. Stripped of my beliefs, behaviours and character, I would not be me. Others, like our current emotional state or knowledge of specifics of the world around us, do not. While my mental street map of the city in which I live may change depending on which city I live in, that does not mean I am a different person.(use a better example). Hence, an immortals experience could indeed change the peripheral elements of their mind, but leave the core untouched.

Objection: something

Not all persons must have a internal state.

Just because humans have an alterable mind does not mean all persons must. What if our immortal was not changed by their experiences. What if they were an a-priori perfect game player, able to compete effectively without any adaptation. What if they were, to take it to an extreme, a giant lookup table with reactions to every possible series of external stimuli hard-coded into the?

I'm not sure, but my intuition here is that this kind of lifeform is not a person. Why? Let's go through the objection tree.

• A lookup table containing all possible reactions to all stimuli cannot exist in the physical universe.
• Irrelevant. 1: it's a thought experiment. 2: A standard mind can be represented as a look-up table if you know the inputs it will recieve. Even if you don't, it can be a look up table where some inputs lead to a different lookup table which replaces the baseline one.
• All minds must have internal states. No internal state = not conscious = not a mind.
• True. But why must that internal state be malleable?
• To account for a changing world.
• What if the world is static?
• What if the static model is powerful enough to account for the world without further changes/optimization?
• 
  
• Life = change. 

* They're not dead either, but that's a discussion for another article.

** There should be separate words for alive in the sense of a living organism and alive in the sense of a person/conscious being continuing to exist. i.e: I can suffer brain death and cease to exist, but my body, the organism which hosts me, can continue to live.

Effective Altruism and individualism

The effective altruism movement ignores one of the most significant ways to do good: raising good children*. It pays to remember that ideas don't exist in a vacuum. They are shaped by the society they reside in and the same idea in different places can be very different indeed.

Further reading:
https://thingofthings.wordpress.com/2015/09/30/having-children-as-effective-altruism/
http://effective-altruism.com/ea/66/parenthood_and_effective_altruism/

*It is possible that having children is not good. For the purpose of this argument, that is irrelevant. You can raise children without having them by adopting

Life as uniqueness.

The Thesis: Two identical brains in two identical worlds which are guaranteed to lead two absolutely identical lives, both in terms of internal subjective experience and in terms of their objective effect upon the world, are not different people.

1: Is personhood physical? (Spoiler: No)

If you think physical location defines a person, by that logic, if I were to move a step to the left, I would be a different person. (unless you have a very strange definition of a person where personhood is entangled with the environment). 

Does personhood requires physical continuity? What is physical continuity? Is it that the atoms in my body must be the same? Then I am a different person every 7 years. Every breath lessens me. Also, it implies a strange physicalism where a person resides in their atoms but not in other, empirically identical atoms. I do not see why replacing one carbon atom in a dendrite in my brain with an identical carbon atom makes me less me. Those who do are better off becoming shamans.

2: Is personhood causal?

Is it that a chain of causation must stretch from me to future me's? Why? No good definition of personhood or any phenomenon can depend on unrelated past states. A good definition must be empirical, based on the present configuration of the universe rather than past events. The alternative is to believe that two identical people in identical places with identical futures are different people only because of their pasts, To me this is insane. If you're not convinced, too bad.

(Rationality 101: Definitions of things that exist independently of our minds cannot be based on things that exist only in our minds, such as causation. Reality, like good code, is stateless)

3: Is personhood relational?

Some would argue that a person is only a person if their are other people they interact with. I don't think so.

1. Counterexample:If a meteor strike kills everyone except for me, I am still a person.
2. Even if humans can't develop into real people without socialisation, that isn't to say that is true of all possible lifeforms/people
3. A person is not entirely defined by their relationships. That is why if you replaced a human child with a dog, and treated the dog in an identical fashion, it would not grow into the same person.
4. There is a deeper problem with this definition, which is that it treats people as black boxes and only looks at how they interact with the external world, ignoring any differences in internal states. This is wrong. Put me and my girlfriend in front of a computer terminal which is our sole access to the external world. Give us only one key on the terminal which sends hello to the person on the other end. We produce the same output, but that does not mean we are the same person. We have different values, thoughts and feelings.

3: What is personhood

Who you are is defined, loosely, by what beliefs, values and preferences you hold. More strictly, what kind of person you are is defined by your internal state. There is an N-Dimensional person-space and you are somewhere in it. One perspective is that you are a point in this space. The problem with this is that it means that every tiny change makes you a different person. A better perspective is that a certain region or cloud of that space is you, more so at the enter and less as you move further away. You gradually change over days and months depending on your moods, emotions, growth etc.. but are, in the short term, similar enough to yourself that you are effectively the same person.

Perfect Free Markets Are Bad: Long term investment is impossible

The argument:

In a perfect free market, noncompetitive firms are instantly replaced. Thus, firms cannot make long term investments. The overwhelming majority of investment in tomorrow have a cost that must be paid today. That cost must be paid for somehow, usually through price increases. This is impossible. In perfect markets, no consumer will buy a product which has indistinguishable perfect substitutes for a lower price.

The Flaw:

There are other forms of funding. Investment by outside parties in exchange for a proportion of the returns is one. Debt with delayed repayments is another.