This piece assumes that the reader already knew, or has by now taken on board, the sense of ARGUMENTUM AD HOMINEM which earlier posts of mine explained. The following example of this argumentum is taken from the great Anglican Catholic theologian Dr Eric Mascall.
Fr Eric is dealing with the claim that Anglo-Catholics are subversive Quislings because they try to reverse, within the Church of England, the changes made at the Reformation. He points out that it ill becomes those who support the Reformation Settlement to argue that a status quo should never be changed.
Let's unpack that or, to use Fr Zed's neat term, 'drill into it'. [What follows is Hunwicke, not Mascall.]
Someone who believes "Changing a status quo is always bad" cannot be a supporter of what was done at the Reformation. Because, in that period, a status quo was changed.
Someone who supports what was done at the Reformation cannot also, simultaneously, believe that "Changing a status quo is always bad", because that is exactly what the 'Reformers' did.
Of course, it is open to anyone to say "Ah, but the status quo which the 'Reformers' changed was a wicked and corrupt status quo and so they were right to change it; but the present status quo is a good one, so you are wicked to try to change that". That is fair enough, because you and he can then dialogue or argue about whether the two claims in his statement are in fact true.
If he modifies his assertion of principle to "Bad status quos should always be changed and good ones should always be preserved", then he has shifted his ground to a rational (if a somewhat blindingly obvious) stand. You may well agree with him, while insisting that it is necessary to apply the two halves of his proposition with dispassionate care.
What he is not entitled to do, not today, not ever, not even on the Day of Judgement, is to have his cake and eat it: to rant about how "change is always per se wrong" when it suits him, and then to change horses to "Change is sometimes necessary" when that suits him. If he persists in trying to have things both ways, there is no point in wasting your time on arguing with him.
We could disentangle this from inter-Anglican squabbles and apply it to the Catholic Church of 2016 by considering the attitudes of the 1970s Liturgical Fetichists who dislike Cardinal Sarah's recent admirable and admirably repeated call for worship Ad Orientem and who also claim that it is totally beyond the pale even to imagine reversing the gigantic changes made in the 1970s; forgetful as they are of how vicious and radical were those changes of the 1970s.
A traddy Socrates would (despite his own very profound dislike of the 1970s 'reforms') probably start by cunningly representing himself as being where his interlocutor actually is (as a supporter of the 1970s 'reforms') by saying ...
Socrates Do you agree that the 1970s liturgical reforms were a good thing?
1970s Liturgical Fetichist I jolly well do (panu ge).
Socrates And did those reforms constitute a profound change in the inaccessible, guilt-ridden, incomprehensible, clericalist and hide-bound Liturgy of the pre-Conciliar Church?
1970s Liturgical Fetichist Dead right, Socrates, that's just what they did. You never said a truer word (panu men oun, kai alethe legeis).
Socrates So when the 1970s reformers made their root-and-branch changes, they did well?
1970s Liturgical Fetichist B****y well, if you'll forgive the French, Socrates me old chum (kai mala, o sokratidion, houto phainetai).
Socrates It seems, then, that we are agreed that change can sometimes be necessary?
1970s Liturgical Fetichist Yeah, well, fair do's, I s'pose we are, if you put it like that (alla moi dokeis ge, o sokrates, metrios legein, kai houto tithemai).
Socrates So if it were to appear upon further study that what Cardinal Sarah and the Traddies are currently trying to do to the worship of the Catholic Church is a necessary change, then we would need to applaud them and to follow them?
1970s Liturgical Fetichist Crikey! I don't at all like the sound of that! (ou ma ton Dia).
Socrates But you cannot both agree that change may be necessary, and say that we must refuse to consider the changes proposed by Sarah and the Traddies. *ei gar tauta amphotera ereis, oukh hoios t'esei sumphonein soi.
There is the essence of the Argumentum ad hominem, in that last sentence of Socrates: *"For if you are going to say both these things, you will not be able to be in agreement with yourself".
This, the Argumentum ad hominem, is how B John Henry Newman confessed that he amused himself in the Oriel Common Room by playing with slower people; this is the sort of device that Dom Gregory Dix so relished. Not to mention Mgr Ronald Knox, Protonotary Apostolic, and Fr Eric Mascall. Even Socrates and ... your humble servant. As Locke pithily described it, the Argumentum ad hominem is "Pressing a man with the Consequences of his own Principles or Concessions". Aesthetically, at its best it affords you the pleasure of watching, perhaps with a vivid glass of Kiwi Sauvignon Blanc in hand, as your adversary squirms and wriggles on the painful horns of a dilemma which ... am I mixing my metaphors? ... he has walked right into.
There are, surely, in God's wonderland of pleasures, few sweeter, more exquisite, delights than contemplating that? You agree? Panu ge!!
* Plato, the Cratylus, 433B.