Why?

In which Good Dr. Krugman re-plows the most well-tilled soil in America:

Slavery’s Long Shadow
JUNE 22, 2015

America is a much less racist nation than it used to be, and I’m not just talking about the still remarkable fact that an African-American occupies the White House. The raw institutional racism that prevailed before the civil rights movement ended Jim Crow is gone, although subtler discrimination persists. Individual attitudes have changed, too, dramatically in some cases. For example, as recently as the 1980s half of Americans opposed interracial marriage, a position now held by only a tiny minority.

Yet racial hatred is still a potent force in our society, as we’ve just been reminded to our horror. And I’m sorry to say this, but the racial divide is still a defining feature of our political economy, the reason America is unique among advanced nations in its harsh treatment of the less fortunate and its willingness to tolerate unnecessary suffering among its citizens.

Of course, saying this brings angry denials from many conservatives, so let me try to be cool and careful here, and cite some of the overwhelming evidence for the continuing centrality of race in our national politics.
...

So...why, Paul?

Why be "cool and careful here"?

Why be anything in particular at all?

You are reciting for the umpteenth time the bare facts of one of the most well-documented and easily checked strata of American history.

It is the Year of Our Lord 2015*, and and for most of the adult lives of anyone who might read your column, Conservatism has been an unbroken series of lies, bloody catastrophes, more lies and casual sedition while a scorching magma of rage, racist and paranoia roils just below a thin crust of mainstream media respectability.

Anyone still hanging onto their Conservatism at this late date is either a making a buck as a willing co-conspirator, or is a willing dupe irretrievably beyond the event horizon of wingnut denialism.

Either way, they are lost past redemption, and no magical string of words -- no matter how cool and careful or astringent or logical or kind -- will save them.

*typo corrected.  thanks!