I'll let Justice Scalia answer this one, The following Comes from his Book "A matter of Interpretation: The Federal Courts and the Law."
Perhaps the most glaring defect of a Living Constitutionalism, next to its incompatibility with the whole antievolutionary purpose of a constitution, is that there is no agreement, and no chance of agreement, upon which is to be the guiding principle of the evolution. Panta rei is not a sufficiently informative principle of constitutional interpretation. What is it that the judge must consult to determine when, and in what direction, evolution has occured? Is it the will of the majority, discerned from newspapers, radio talk shows, public opinion polls, and chats at the country club? Is it the philosophy of Hume, or of John Rawls, or of John Stuart Mill, or of Aristotle? As soon as the discussion goes beyond the issue of whether the Constitution is static, the evolutionists divide into as many camps as there are individual views of the good, the true, and the beautiful. I think it is inevitably so, which means that evolutionism is simply not a practical constitutional philosophy.
I do not suggest, mind you, that originalists always agree upon their answer. There is plenty of room for disagreement as to what original meaning was, and even more so how that original meaning applies to the situation before the court. But the originalist at least knows what he is looking for: the original meaning of the text. Often-indeed, I dare say usually-that is easy to discern and simply to apply.
Seventy Five years ago, we believed firmly enough in a rock-solid, unchanging Constitution that we felt it necessary to adopt the Nineteenth Amendment to give women the vote. The battle was not fought in the courts, and few thought it could be, despite the constitutional guarentee of Equal Protection of the Laws; that provision did not, when it was adopted, and hence not in 1920, guarantee equal access to the ballot but permited distinctions not only of age but of property and of sex. Who can doubt that if the issue had been deferred until today, the Constitution would be (formally) unamended, and the courts would be the instrumentality of change?
If the Courts are free to write the Constitution anew, they will, by God, write it the way the majority wants; the appointment and confirmation process will see to that. This, of course, is the end of the Bill of Rights, whose meaning will be committed to the very body it was meant to protect against: the majority. By trying to make the Constitution do everything that needs doing from age to age, we shall have caused it to do nothing at all.