(Excerpted from Originalism, Amy Coney Barrett's approach to the Constitution, explained By Ian Millhiser, Vox.com. See link below)
Originalism, in [Judge Amy Coney] Barrett's words, is the belief that “constitutional text means what it did at the time it was ratified and that this original public meaning is authoritative.”
In reality, however, following the text of the Constitution is more complicated than it sounds.
For one thing, the Constitution is riddled with ambiguous language. What are the "privileges or immunities of citizens of the United States"? What makes a search or seizure "unreasonable"? If the government wants to deny "liberty," how much "process" is "due"? What's a "public use" of private property? What is the "general welfare of the United States"?
Then there's the problem of precedent...
To give one rather stark example, there was a robust debate among early Americans about whether it is constitutional for the federal government to fund "internal improvements" such as roads and canals. As president, James Madison even vetoed an 1817 bill funding such construction because he deemed it unconstitutional.
Madison's views are now widely rejected. But suppose that a Supreme Court dominated by originalists concludes that Madison was correct. Does that mean the entire federal highway system must be torn up?
Another problem with Originalism, is that the Founders were not clairvoyant. They could not envision the entire future from their 18th century perspective.
For example, the First Amendment mentions "the press" meaning newspapers and other printed matter. Radio, television and the Internet were beyond their imagination. We assume, but cannot know from their written words, that they intended to protect all of modern news media from government interference.
Likewise, in the Second Amendment, the "individual right to keep and bear arms" in an age of muskets didn't foresee the weaponry technology of the today.
When the Bill of Rights was written, only only white male adult property owners who were at least 21 years old could vote. Depending on the state, a man needed to own fifty or hundred acres of land to have the right to vote. Women and non-white people had no voting rights. Since only voters could serve on juries, most people could not truly have a jury of their peers.
That was our original voting rights and restrictions. Not many people today would advocate that we return to that era.