Post hoc ergo propter hoc arguments are invalid.
Part of the formal study of philosophy is the science of logic. Logic results from our applying reason to argument and making correct or reliable inference. Logic is sound judgment.
It is logical to draw the conclusion that "John is mortal" when we propose this argument: "All men are mortal; John is a man; therefore John is mortal."
This syllogism, made up of a major premise ("All men are mortal") and a minor premise ("John is a man"), leads to the logical (reasonable, reliable) conclusion that "John is mortal."
Not every appeal to logic, that is, to a reasonable, reliable conclusion, is valid. A post hoc argument is contrary to reason.
Post hoc, ergo propter hoc reasoning argues that one event ("B") happened after another event ("A"), and therefore "A" must have caused "B" to happen.
For example, "I washed my car on Monday, that's why it rained on Tuesday." This kind of argumentation is logical fallacy, also known as false cause or correlation but not causation.
Just because something happened after something else, does not mean that the something else caused the something to happen. Nor can we conclude that avoiding "A" will prevent "B."
If you are still with me, I hasten to add that my reason for all this philosophizing is to debunk the arguments that the troubles we are now experiencing in the Church are caused by the Second Vatican Council.
I've heard it said that the reason we have a scarcity of priests is because of Vatican II. I've heard it said that the reason we have fewer Catholics going to Mass on Sunday is Vatican II. I've even heard it said that the reason for the pedophilia scandal in the Church is Vatican II.
These are examples of post hoc ergo propter hoc thinking, and the conclusions are illogical and invalid.
Long before Pope John XXIII was elected pope (1958) and called for an ecumenical council (1962-65), the Church was showing signs of a decline in priestly vocations. For example, Archbishop Karl J. Alter of Cincinnati in the 1950s noted "a threatening shortage of priests for the immediate future" in his diocese. The same situation was more obvious throughout Europe.
Those who propose that decline in Mass attendance is the result of Vatican II liturgical changes forget to factor in what Michael Casey, OCSO, a monk and prolific writer in Australia, calls "the movement of secularisation that swept through the West in the 1960s." He points to the social changes of that decade which "resulted both from the technological advances and as reaction to the serial horrors of the twentieth century."
You cannot blame Vatican II nor logically connect changes in the Church with the rebellion of the beatnik generation, the atrocities of the war in Viet Nam, the technological exploration of space, the struggle for racial equality, or the mind-numbing drugs and free-love of Woodstock.
And for decades before Vatican II the problem of pedophilia by priests was known and quietly, secretly, and ineffectively managed by bishops in dioceses around the world.
These and other forces were already at work changing people and cultures prior to Vatican II. Among those forces were new means of social communication, yearning for freedom by those under despotic governments, the threat and fears of nuclear annihilation, re-discovery of liturgical practices of an earlier age. Catholics were not unaffected by these cultural influences.
Blaming Vatican II for these current problems is an example of logical fallacy, even if we acknowledge that some of the things done in the Council's name were ill-considered and poorly implemented.
Post hoc ergo propter hoc arguments are not valid.
What is valid is the recognition that we cannot go back to an idealized past. All the Latin and cassocks and novenas we can muster will never bring the Church back to what it was in the 1950s. The nostalgia is understandable, but it lacks logic.
No, Vatican II set a course for the Church, and our best bet is to respond wholeheartedly to its direction.
In the area of liturgy Vatican II encouraged us to participate actively, to return to a noble simplicity in ritual, to think of liturgy as the summit toward which the activity of the Church is directed.
In relating to others, we were urged to enter into ecumenical dialogue with people of other religions, to use the medicine of mercy rather than of condemnation, to promote religious freedom, to be of service to all mankind.
In our personal and communal spirituality, we were advised to read and pray with the Bible, to evangelize, to reflect the ideals of marriage and family life, to think of the Eucharist as the source and summit of the Christian life.
Pardon me if you think I am pre-occupied with the Second Vatican Council. I think and write of it often. My repetitive referrals to that Council are prompted by my conviction that the Council has pointed us in the right direction. I have a 20-year old sweatshirt imprinted with these words: "Join the revolution! Support Vatican II!"
My faith and logic tell me it is still the way to go.