If the Pope is talking about an abstraction that nobody has ever advocated (not even Ayn Rand), fine. He can make that clear.
“Trickle down” is left-wing code for the neo-liberalism of Ronald Reagan, Margaret Thatcher, Bill Clinton and Tony Blair. Many people, both on the left and the right, recognize this - neo-liberalism - to be what he is referring to.
Ever since the church got into “social encyclicals” (usually dated as of 1891), the church has swayed back and forth between capitalism (Centesimus Anos) and fascism (Quadrilisimo Anos) (sp?). So, there is room there for a range of views. By fascism, I mean a big but less than totalitarian state, where property is nominally private but is highly regulated by the government. Mussolini’s Italy, Franco’s Spain and Peron’s Argentina would be examples.
I myself rather liked Benedict’s spontaneous statement, Christianity is not a political or an economic system. But, I did not like his skipping over Centisimum Anos to tie-into Populorum Progresso (sp?), to argue that all we really need to love one another to advocate economic policy (oh, provided we reject what he calls “free market fundamentalism,” whatever that means). Sorry, but this sound to me like saying all we have to do is love one another to know how many moons Jupiter has.
That's not comprehensive, but it's better than nothing!
Anyway, what I emphasized about QA was that Pope Pius XI was writing in 1931, when the capitalist world was in crisis, tens of millions in the "developed world" were not just poor but destitute, and the options facing collapsing societies seemed to narrow down to either Fascism (Mussolini and his admirers in many nations) and Communism (exemplified not just by the Soviet Union, but such leaders as Mexican Plutarco Elias Calles.) In this terrible milieu, Pius dared to declare private property to be essential for the development and freedom of the individual. He said that those who deny private property deny personal freedom and development. He also said private property has a social function --- it can unite and build, or divide and destroy --- and it loses its morality when it leads to the ruin of millions of vulnerable people.
He did not endorse Socialism.
Here's a couple of direct quotes from QA:
117 "Whether considered as a doctrine, or an historical fact, or a movement, Socialism, if it remains truly Socialism, even after it has yielded to truth and justice on the points which we have mentioned, cannot be reconciled with the teachings of the Catholic Church because its concept of society itself is utterly foreign to Christian truth."
118 "Socialism, on the other hand, wholly ignoring and indifferent to this sublime end of both man and society, affirms that human association has been instituted for the sake of material advantage alone."
So he warned against both the rapaciousness of "the Wolves of Wall Street" and the false solution of socialism.
He did not address the technicalities of economics (we haven't had a pope yet who was trained in economics)but in the broad strokes of morality as we know it from the Prophets of Israel, the Fathers of the Church, and Natural Law.