In the case of life on other worlds we have not the foggiest idea how many sides the dice has.
Rubbish! Off the top of my head I would say that the number of sides is not very high. The planet would have to be composed of elements capable of interaction to form compounds, it would have to be within a certain band of distance from its sun, and probably a few other things which a chemist/biologist would know about, but that's all.
(a) We are talking about planets which have life on them, not planets with conditions capable of sustaining life. The two need not be the same value.
(b) I see the "rubbish" when I say we don't know what the odds are... but I don't see the odds. What are the odds, Len?
I don't know what the odds are any more than you do, but they certainly don't run into the millions you were claiming.
Professor Andrew Watson, of the University of East Anglia, does have an idea:
He suggests the number of evolutionary steps needed to create intelligent life, in the case of humans, is four. These probably include the emergence of single-celled bacteria, complex cells, specialized cells allowing complex life forms, and intelligent life with an established language.
“Complex life is separated from the simplest life forms by several very unlikely steps and therefore will be much less common. Intelligence is one step further, so it is much less common still,” said Prof Watson.
His model, published in the journal Astrobiology, suggests an upper limit for the probability of each step occurring is 10 per cent or less, so the chances of intelligent life emerging is low – less than 0.01 per cent over four billion years.