Dear Eckard,
Most essays considered the context of the word "humanity" in the contest question and it fits your definition #1 (mankind), though many also thought that our future would be brighter if we all acted more like definition #3 (show kindness).
You wrote: "To Muslims the doctrine "as many (Muslim) children as possible" is a value in the sense of #3, and when I lived together with a Tunesian he told me why: The more children, the more food for the elderly."
In a primitive society with no pension plans or social security, that certainly makes logical sense, don't you think?
Rich countries have fewer children, and they also take better care of their environment (even if they keep growing their population). So ask the next question (as Ted Sturgeon always urged): Why aren't you trying making everyone rich?
Again, ask the next question: Why do Muslim countries (on average, even with all that Middle East oil) have the lowest standard of living on this planet?
It's because they believe that Allah is utterly transcendent, and as Master over us slaves, he is not necessarily beneficent nor ordered. This is what Al-Ghazali, the 2nd-most influential prophet (after Mohammed himself), in fact did teach. The unintended consequence of this was that it destroyed the fledgling sciences in the once-great Islamic civilization--by denying that God's universe had predictable causes or that any causes would make sense. Science breeds technology, and technology is the lever of wealth, because it allows everyone to accomplish more with less. Hence the low standard of living for Islam.
You admitted that "the notion overpopulation lacks a reference value".
I'm not sure what you mean by that, other than the fact the carrying capacity of an environment can be (and has been) changed considerably; first by the evolution of photosynthesis (which poisoned the atmosphere and caused a 300 million year ice age), then the evolution of multi-cellularism (the most totalitarian regime possible), the development of consciousness (which made psychological suffering possible; as opposed to only physical pain), and more recently the invention of fire, agriculture, food preservation, and the green revolution. Each step significantly increased the carrying capacity of Earth, though it changed the environment significantly too. It seems that you cannot imagine the next step, so it cannot happen. Please read my essay on "Three Crucial Technologies" and tell me why nanotechnology and expanding into Space won't increase the carrying capacity of this solar system by many magnitudes.
Are a conservative in the traditional sense: afraid of change?
You also said, "It is indisputable that the consequences of unlimited growth cannot forever compensated."
I bed to differ. Our single-celled bacterial ancestors would probably have said the same thing 3.6 billion years ago. As Malthus said more than 200 years ago. Isn't it indisputable that the exponential growth of Moore's Law and Kurzweil's more general Law of Accelerating Returns have a much faster growth rate than human reproduction? (e.g. 18 months vs 30 years) I will concede that according to our best current scientific theories, Asimov's ball of flesh can't expand any faster than the speed of light.
Finally, you said, "Ethics needs to be modified, and I consider this a pressing most fundamental necessity."
Ethics *ought* to be modified? Do you realize the inherent contradiction in your statement? How can you apply an imperative to changing a set of imperatives? You can't. At any rate, Ethics is objective, not subjective. If it was subjective, then it would only be an individual's or group's changing opinion. How do you know that it isn't your "personal ethics" that needs to be changed?
What's wrong with having a ball of humanity augmented by silicon, diamondoid, biology, and superconducting machines expanding into the universe at light speed, transforming all the dead matter in the universe into life that thinks, feels, and loves?