So instead of every civ fillings its galaxy, we get every civ building one in every galaxy. For this to not result in an Engine on every star, you still have to fine-tune the argument such that new civs are somehow very rare.
There are some hypotheticals where the details are largely irrelevant, and you can back up and say “there are many possibilities of this form, so the unlikeliness of my easy-to-present example isn’t the point”. “Alien civs exist, but prefer to spread out a lot” does not appear to be such a solution. As such, the requirement for fine-tuning and multiple kinds of exotic physics seem to me like sufficiently burdensome details that this makes a bad candidate.
On some level it’s fine to make the kinds of qualitative arguments you are making. However, to assess whether a given hypothesis really robust to parameters like ubiquity of civilizations, colonization speed, and alien psychology, you have to start formulating models and actually quantify the size of the parameter space which would result in a particular prediction. A while ago I wrote a tutorial on how to do this:
which covers the basics, but to incorporate alien psychology you would have formulate the relevant game-theoretic models as well.
The pitfall of the kinds of qualitative arguments you are making is that you risk confusing the fact that “I found a particular region of the parameter space where your theory doesn’t work” with the conclusion that “Your theory only works in a small region of the parameter space.” It is true that under certain conditions regarding ubiquity of civilizations, colonization speed, and alien diplomatic strategy, that Catastrophe Engines end up being built on every star. However, you go on to claim that in most of the parameter space, such an outcome occurs, and that the Fermi Paradox is only observed in a small exceptional part of the parameter space. Given my experience with this kind of modeling, I predict that Catastrophe Engines actually are robust to all but the most implausible assumptions about ubiquity of intelligent life, colonization speed, and alien psychology, but you obviously don’t need to take my word on it. On the other hand, you’d have to come up with some quantitative models to convince me of the validity of your criticisms. In any case, continuing to argue on a purely philosophical level won’t serve to resolve our disagreement.
So instead of every civ fillings its galaxy, we get every civ building one in every galaxy. For this to not result in an Engine on every star, you still have to fine-tune the argument such that new civs are somehow very rare.
There are some hypotheticals where the details are largely irrelevant, and you can back up and say “there are many possibilities of this form, so the unlikeliness of my easy-to-present example isn’t the point”. “Alien civs exist, but prefer to spread out a lot” does not appear to be such a solution. As such, the requirement for fine-tuning and multiple kinds of exotic physics seem to me like sufficiently burdensome details that this makes a bad candidate.
EDIT: Edited my response to be more instructive.
On some level it’s fine to make the kinds of qualitative arguments you are making. However, to assess whether a given hypothesis really robust to parameters like ubiquity of civilizations, colonization speed, and alien psychology, you have to start formulating models and actually quantify the size of the parameter space which would result in a particular prediction. A while ago I wrote a tutorial on how to do this:
http://lesswrong.com/lw/5q7/colonization_models_a_tutorial_on_computational/
which covers the basics, but to incorporate alien psychology you would have formulate the relevant game-theoretic models as well.
The pitfall of the kinds of qualitative arguments you are making is that you risk confusing the fact that “I found a particular region of the parameter space where your theory doesn’t work” with the conclusion that “Your theory only works in a small region of the parameter space.” It is true that under certain conditions regarding ubiquity of civilizations, colonization speed, and alien diplomatic strategy, that Catastrophe Engines end up being built on every star. However, you go on to claim that in most of the parameter space, such an outcome occurs, and that the Fermi Paradox is only observed in a small exceptional part of the parameter space. Given my experience with this kind of modeling, I predict that Catastrophe Engines actually are robust to all but the most implausible assumptions about ubiquity of intelligent life, colonization speed, and alien psychology, but you obviously don’t need to take my word on it. On the other hand, you’d have to come up with some quantitative models to convince me of the validity of your criticisms. In any case, continuing to argue on a purely philosophical level won’t serve to resolve our disagreement.