Liberals may have appeared complacent and out of touch, but nobody has contributed more to exacerbating these divisions than Mr. Kaczynski — whether through his narrative about the rottenness of Poland today and his vision of a morally sound Fourth Republic, or through his allusions that the airplane crash in Smolensk in 2010 in which his twin brother, President Lech Kaczynski, died might have been orchestrated and covered up by the Russians.

For Mr. Kaczynski and his supporters, attitudes about “Smolensk” became the measure of patriotism and belonging to the national community. Those who debunked the plot version as a myth did not deserve to be called “true Poles.”

So, while the crisis over the Constitutional Tribunal might be the next chapter in the process of driving the two Polands apart, it is not the whole story.

Social and political tensions are embedded in Poland’s much deeper moral and cultural divide. Just as the historian Gertrude Himmelfarb famously described the United States as “one nation, two cultures,” the Polish social psychologist Michal Bilewicz says Poland is composed of two tribes who adhere to different moral and value systems.

On one side are those representing conservative or Catholic values and stressing national pride and loyalty; on the other are those who highlight individual rights, embrace minorities and put universal justice before community solidarity. These two tribes have little in common. They hardly communicate, they often despise each other — and the language of the political debate on both sides is extremely polarized if not brutal.

Poland found a way to overcome this in the past. In 1989 a compromise between Communists and the opposition made a transition to democracy possible in Poland, and that ability to compromise became a source of national pride and international respect. But the space in which compromises can be forged has shrunk. The center of society has been poorly served by liberals and actively riven by national-conservatives like Mr. Kaczynski.

The current turmoil, provoked and consciously stirred by the Law and Justice party, will further poison the political culture in a society where the lack of social capital, polarization and refusal to compromise are the central obstacles for future development and modernization.