Why should current policymakers be restrained from doing what they think is right because "a group of white propertied men who have been dead for two centuries, knew nothing of our present situation, acted illegally under existing law and thought it was fine to own slaves might have disagreed with this course of action"?
In reality, this has been the default position of the left for quite some time, although rarely are they this explicit about it. In all the years I've paid attention to politics, I have never once heard anyone on the left lament that the Constitution stood in the way of them enacting any policy they could get passed by the legislative branch and signed by the executive. (To be fair, not all elected conservatives appear to acknowledge such restrictions, either.) Nancy Pelosi's incredulous reaction to a question about the constitutionality of Obamacare is just one example.
For his part, Seidman does identify certain principles of the Constitution that he believes do deserve preservation.
Freedom of speech and religion, equal protection of the laws and protections against governmental deprivation of life, liberty or property are important, whether or not they are in the Constitution. We should continue to follow those requirements out of respect, not obligation.How are we to know which requirements we should follow and which we are free to ignore? Maybe we could write them down in some document somewhere. Wait, never mind.