I have to say that the conclusions drawn by Bishop Sherrington seem to me broadly in line with the the principles of Moral Theology in the manuals I have described. Regular readers of this blog will hardly consider me to be a venal patsy of the English Bishops: quite the opposite ... I think they need careful watching. Their behaviour during the years after 1992, when we were trying to secure a Corporate Solution to our problems; and their conduct with regard to the Magisterium of Benedict XVI, do not always inspire confidence. But they are not necessarily, always, ex officio, wrong.
I do not think they are wrong in the guidance they are offering at this particular time and in this particular matter. But I am aware that bishops elsewhere in the world, including some whom I and many readers will respect, have taken a different view.
Accordingly, I think it has to be admitted that we have a situation in which, as an objective historical fact, there exists Doubt.
So does Doubt mean that a real Christian should go for the strictest conclusion, thereby making sure that she is "on the safe side"?
NO! It means that we are in the area once known to moralists as "the Doubtful Conscience". Much discussion used to go on about how we deal with this phenomenon! Since the 1960s, such discussion has unfortunately been replaced by the dodgy actions of shifty practicioners who present us, instead, with systems of morality ("Situation Ethics"?) in which there is no definite Right or Wrong at all. Heretics, the lot of them! I would commend to readers the fine passage in Veritatis Splendor from paragraph 79 onwards.
So we'll forget all those megaheretical Trendies and go back to the dusty old manuals; back to S Alfonso and Davis and Pruemmer and even Bishop Mortimer.
This, therefore, is the traditional approach the Doubtful Conscience.
We are offered different pastoral systems, with exciting names like Rigorism, Tutiorism, Probabiliorism, Aequiprobabilism, Probabilism, and Laxism. Some of these have been condemned by the Magisterium, some not. A Christian, and his Confessor, has the liberty to adopt any of these systems ... except the condemned ones! To keep this narrative within reasonable lengths, I will deal only with Probabilism.
For the probabilist, if a Christian is facing a choice between two (or more!) moral choices, and each of them seems really to have a very great deal to be said for it, then each of the contemplated choices is termed 'Probable'. And, in this situation, she is free to opt for either. She may think: "Well, A has a lot to be said for it ... has a real chance of being right ... but I think, on balance, B has its nose just across the line", but she may still choose and do A. Lucky girl, she is entitled to bet on horses which get a place, not merely upon winners!
That pre-Conciliar Moral Theology had a flexibility and was genuinely pastoral. No rigidity there! What it means for the the current matter under review is that you don't have to go for the tougher choice, 'being on the safe side', even if you feel that the arguments that way are a bit stronger. You are at liberty to go for the 'easier' option as long as it is a real option with four legs and is still in it with a chance as the horses enter the final furlong.
I sometimes feel that in the current ecclesial situation, which catastrophically includes a pope who refuses to teach clearly and faithfully, there is the following very dangerous risk: the danger that 'Traditionalist' Christians, being determined not to go down the path of the crooks and false guides who proliferated after the Council, will instead opt for "always being on the safe side" ... i.e. the Rigorist option.
But Rigorism was condemned by Pope Alexander VIII in 1690! It's not, therefore, available to a good Catholic who tries to live according to the traditional teaching of the Catholic Church.
So, in the question "Can I use a vaccine derived from genetic material taken from murdered foetuses?", even if the 'tougher' solution, "No", seems to you to have the better argument, you may still go for the 'easier' option put before you by Bishop Sherrington in the name of the English bishops. As long as you conscientiously believe that it does have some sort of decent chance of being right.
Being a Traditionalist means taking seriously what the 'Democracy of the Past' offers you, even when it is currently unfashionable. Being a Traditionalist does not mean standing fearfully with your back to the wall, terrified of getting something wrong. God is merciful and knows you better even than you know yourself. We are to use His grace, trustingly, and then leave the issue to Him.
And I do not believe that confessors, and guides of souls, have any right to try to impose upon Christifideles laici any tougher course of action.