AAA's argument, which is the argument of the originalist/strict constructionist, in general, is that there is only one way to read the Constitution, i.e., with the express intent of the founders and with nothing else.
Well, reality is that the founders are all DEAD, and no one knows what their express intent was. Let's get real for a second. At the time of the Constitution, men were omnipotent, and women and children were not much more than chattel property.
If the issue of abortion had actually been presented to the Supreme Court in 1790, just to pick a date out of the blue, I suggest that it is highly likely that the court would have ruled that the decision of whether or not to abort the life should be left up to the husband, or father, if identifiable, because a man is traditionally the person who is responsible for the custody and control of children in minority (this was the fact at the time -- father's had absolute control over children).
If no father were identifiable, then the court would probably have assumed the role of male parent and determined what was in the mother's best interest and ordered it.
Modernly, we would all view the above as absurd. So, for abortion there really isn't any originalist view -- it's all just personal opinion dressed in the emperor's new clothes.
As far as other subjects go, the founders wouldn't have know what to do with zoning regulations or homeowner's associations, they wouldn't have even considered the uniform commercial code, because there wasn't any, yet, they would have laughed at the idea that a man could be ordered to pay support to his spouse for the sole benefit of the child, absent a showing of breach of the marital contract, or tortious injury to the woman or child, they would have found attempts to control drugs, alcohol, tobacco and firearms within the borders of the states to be an overreach by the federal government -- need I go on?
The originalist view of the Constitution is a legal fiction, and a bad one at that, because times have changed, and the Constitution has been amended.
The reality, once you disrobe the justices from their robes, is that what the Constitution means is nothing more and nothing less than what the nine justices say it means, and the idea that there is anything to "find" in the instrument is ridiculous.
The meaning of Constitution of the United States is simply the opinion of the nine justices, who happen to sit on the court at any given instant. Lower courts give stare decisis to prior justices opinions of what the Constitution is, and until the justices change their minds, the lower courts continue to apply the last rule issued, where that rule can be ascertained.
Your statement that pragmatism by the high court would lead to chaos is not supported by the reality that lower courts will observe the high court's decisions, as much as is possible. Only the high court has the ultimate power to deal with issues in a pragmatic manner, because the high court can simply choose to announce its rules as applied to one case or to many.
In eminent domain actions, the high court has consistently stated that all courts must deal with such issues on a case by case bases, and that the high court would do similarly. And, the high court has frequently chosen to narrowly confine its decisions to one set of facts, in other areas, as well (See Escobedo v. Illinois, for a criminal procedure case in point).
Originalism leads to injustice, because it ignores the pleadings of the parties (remember, that a pleading always has a prayer for relief, and that's what courts are ultimately supposed to do -- provide relief for litigants). And, liberal interpretation (natural law) leads to violations of the separation of powers, because the judges start "finding" law to make the Constitution "work."
Legal pragmatism leads to one thing -- justice.