You mean you think the constitution has no underlying philosophic principles? Subsidarity is one of these. Individuals in families, in Churches, and in businesses are more fundamental than local government. Local governments are responsive to these than either state or federal government. The demand that a man be judged by his peers, that the law by which he is bound shall be written by men elected by him and his peers, is based on the idea that power should be exercised by those as close as possible the persons most directly affected.
It is not necessary or helpful to focus on the sort of general concepts to which you allude; although I will certainly acknowledge that in all of its functions, it looks to a maximum level of individual responsibility in order for our system to work. And that is certainly not inconsistent with the philosophic claim that you make. But you are trying to over-explain, what is clear without looking for some structure that may be generally, though not necessarily inevitably, consistent.
But Santorum has been trying to explain away the fact that he really does not recognize the rights of States, local communities, local courts, and individuals, to make decisions with which he does not agree. He may think that limitations on central authority are a good thing; he cannot be trusted to always recognize them.
Again, to specifically illustrate my point, consider the fact that he was one of those who supported the Federal intrusion into the Schiaavo case, which reflected extremely flawed judgment--both Constitutional & tactical, for that matter. (See Schiavo Case.)
William Flax