My point is that if scientifically ALL possibilities must be looked at.
Viviane: Not even close. Not how science works. Before you jump into biology, take a class on basic scientific education first. Your grasp of science is woefully lacking.
In order to look at all possibilities, you must consider an infinite number of combinations, for instance, that a rhino made of pigs is responsible for creation, or that drywall spackle is, or that life sprang from nothing with no cause, or that life came from a collision of an ice cream truck and a comet while having lunch in the core of a neutron star.
In practice, the possibilities are often grouped, as are the examples EOM gave. For instance you have a group of theistic explanations, a group of explanations involving life originating on earth, a group of explanations with life originating elsewhere in the universe, etc. Now, it is possible to conjure up an (for all purposes) infinite way of counting these explanations in a number of trivial ways, for instance you can think of life originating an infinite number of places on earth or the infinite possible values of the gravitational constant, however this is clearly not the practical problem of science as these different ways are in practice very often neatly grouped.
In the history of science the to-many-explanations-to-consider problem has very rarely surfaced. For instance before Einstein there was not 100 different physical ideas of coordinate invariance in inertial systems but one, Galilean invariance. With Einstein (well, Lorentz, depending on how you look at things) there was two, Galilean invariance and Lorentz invariance and it was quickly apparent which was the better. Or take the shape of the earth. I can think of a grand total of three ideas in the history of science, cylindrical, flat and round.
In science today I would think that looking at all possibilities is exactly the sort of advice I think one should give to people. To negate the statement one end up with the suggestion that one should not look at some possibilities; however if we are really to take this suggestion seriously, we cannot decide to look or not to look at a possibility by investigating it's properties, because that would exactly require us to look at it in the first place. The advice would then seem to boil down to randomly selecting some ideas over other to look at; i think that exactly characterizes the opposite of being scientific.