Intelligent Design: A perfectly good philosophy, but definitely not a good scientific theory - it contains no testable predictions.
Evolution: An incomplete theory, which hasn't gone all the way in explaining every feature of the incomprehensible diversity of life on the planet. Yet it is testable, and its effects can be seen, especially with developments in genetic research methods. Thus it remains a scientific theory, and instead of introducing a PHILOSOPHY as an alternative, it should merely be pointed out that there is room for new discoveries in the field of biology. Science is based on one slightly less incomplete theory modifying or replacing its incomplete predecessors, not on producing 'truth' on demand.
Gravity, electromagnetism and the rest:
Gravity is the weakest known force, yet incredibly long ranged. It dominates over electromagnetism (EM) at large scales because of the overal neutral charge of material (equal numbers of protons and electrons in atoms mean the electric force is equalised). Yet at short ranges it is the EM forces that dominate: electron sharing between atoms holds molecules together, and repulsion keeps atoms a comfortable distance apart.
On a smaller scale still, it is a very short range but incredibly powerful force (called the strong nuclear force) that dominates, even overcoming the EM repulsion between protons. The interesting thing about this force is it becomes repulsive at even smaller ranges, keeping th nucleus of the atom from collapsing in on itself.
In summary: Gravity, if unchecked, will cause things to collapse indefinitely, which is why we get things like fusion in stars and the occurrence of black holes. Luckily the phenomena associated with the EM and strong nuclear forces are powerful enough under normal circumstances to counteract the gravitational attraction.
At least this is the way it appears to be