Well, to start I'll just say, despite my flippant phrasing above, I am not so naive to think that originalism is a stupid idea. There are people that have forgotten more about law than anyone here will probably ever know on both sides of this debate, so I think there is obviously something to both sides.
But to your point, it's not that they wanted it to mean anything. It's just that the constitution is broad and vague, not because we lack historical context or some window into the mind of Madison, but because it is intentionally vague. Let's take the relevant amendment here:
> The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause...
That phrase "probable cause." Not very specific to my mind. It can't mean anything at all, but it leaves most questions unanswered. Is an anonymous phone tip probable cause? If an officer pulls over a car and the driver is sweating and nervous, is it probable cause to get a warrant to search his house for drugs? What if the driver smells like drugs? What if he is carrying lots of cash? What if there is blood on his shirt? And on and on...
Without the hundred plus years of case law that have worked to develop tests for what qualifies and doesn't qualify as probable cause, it really might mean almost anything. What good does it do to ask, "What would James Madison have thought about a driver that smells like drugs?" He probably would have thought it was an interesting legal question for the courts, that's what! Judges should figure that out by trying to predict the real world outcomes of their decisions, not reading tea leaves in the Federalist papers.
OK, I can see that that is a place where the interpretation is intentionally left up to future courts and precedent.
Since you can't foresee every possible future circumstance, you try to establish a general principle to apply instead.
But I don't think that means all parts of it was intended to be freely reinterpreted to mean anything the people in power in the future wanted. I think the main purpose of the constitution was to prevent that!
But to your point, it's not that they wanted it to mean anything. It's just that the constitution is broad and vague, not because we lack historical context or some window into the mind of Madison, but because it is intentionally vague. Let's take the relevant amendment here:
> The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause...
That phrase "probable cause." Not very specific to my mind. It can't mean anything at all, but it leaves most questions unanswered. Is an anonymous phone tip probable cause? If an officer pulls over a car and the driver is sweating and nervous, is it probable cause to get a warrant to search his house for drugs? What if the driver smells like drugs? What if he is carrying lots of cash? What if there is blood on his shirt? And on and on...
Without the hundred plus years of case law that have worked to develop tests for what qualifies and doesn't qualify as probable cause, it really might mean almost anything. What good does it do to ask, "What would James Madison have thought about a driver that smells like drugs?" He probably would have thought it was an interesting legal question for the courts, that's what! Judges should figure that out by trying to predict the real world outcomes of their decisions, not reading tea leaves in the Federalist papers.
But yea, just like my, opinion, man.