My main point was that there is nobody on earth qualified to talk about what leads to the development of sentience. It's all guesswork, although we have some good ideas which I'm sure the author lays out. The author's assertion that we are special, alone, etc. however is based on a handful of assumptions he makes that are cast into doubt with each successive discovery, i.e. the example of binary systems. I'm aware of the vagaries of long elliptical orbits, but one must also be aware that there are many other factors capable of mitigating their negative effects. All of the examples you laid out CAN have situations hospitable to life; large stars DO have habitable zones, for example- they are just not laid out in the same way. It's a lot more complicated than the shape of the orbit, the presence of a molten core, etc. OttoinGrotto's comment really nails it, I think.
I may look into tracking this book down, as obviously a message board discussion of its main points can't do it or the author justice. Excellent discussion and I am thankful for you bringing out the inner nerd in me on a bleak Saturday morning AlaskaSU.
