As a tangent to a post at "Zippy Catholic" there was some discussion of the terms 'formal cooperation' and 'material cooperation'. At one point Alexander Pruss suggested a line of reasoning, and, because it was tangential to the main post, and couldn't be discussed adequately in a comments box, I decided to post about it here. Alex said:
Suppose that I hate Irishmen, and I put, in a public place not frequented by Irishmen, a barrel of baseball bats and a sign: "Take one and smash an Irishman's window." My intention (assuming there isn't some weird reverse psychology going on) is that Irishmen's windows be smashed. I have performed an act here, the act of putting out the baseball bats and hanging up the sign, with the intention that that act should help with the smashing of Irishmen's windows. That I do not know who, if anyone, will complete the task is irrelevant. It's not a mere velleity--an act has been done, and the act's intention is clear.
Likewise, if I don't put out any bats, but just hang up a sign encouraging people to smash Irishmen's windows, I have done an act whose end is the smashing of Irishmen's windows, and the intended means to the end is that this should be done by people incited through my sign.
But here is something interesting, which may be related to what you're getting at. These two cases are somewhat different from the "standard case" of formal cooperation where one is a secondary agent. For in cases of incitement to an evil, the inciter is actually the primary agent, and the incitee is the secondary agent.
In fact, I think we do recognize this--we treat the person who incited a riot as the guiltiest of the bunch (even if he broke no windows or heads).
(There will, however, be cases where the distinction between primary and secondary agent disappears, because the deliberative structure is too complex to separate out one of the decisions as primary.)
I think this is an interesting line of argument, but I disagree with quite a bit of it. Now, it may help to understand what is meant by formal cooperation and material cooperation. The distinction was made, or at least developed to the point of being generally useful, by Alphonsus Liguori. The difference between the two is that in formal cooperation you are cooperating with someone in one act: you are contributing something the act requires; whereas in material cooperation you are facilitating an act circumstantially. To take a modern example, if you drive someone to an abortion clinic in order that they may have an abortion, you are contributing something essential to the abortion itself -- namely, getting the person to where they can get one -- and doing it deliberately in order that they may have an abortion. You are not actually performing the abortion; you are merely a cooperator. But you are a cooperator in such a way that by your intention and effort you are involved in the particular form or nature of this particular act.
Contrast this with putting the address of abortion clinics on a bulletin board for general viewing. This is cooperation with abortion, of course. But if someone checks the bulletin board, gets an address, and goes to have an abortion, you weren't at any point intending that particular act, so your cooperation can't be formal. Instead of making a contribution to the particular character of particular acts, you are contributing to circumstances that make such acts in general more feasible. Circumstances are as it were the material of human actions, so you are a material cooperator.
Now, if I hate Irishmen, and put out the sign and baseball bats for smashing the windows of Irishmen, I am materially cooperating with any window-smashing that goes on. I'm providing materials that assist acts window-smashing in general. I want Irishmen's windows to be smashed; but this is not enough for intention in the old moral-theology sense in which these technical terms are usually expressed. To determine that you have to look at how I have set about disposing the world in my act: and all I have done is encourage the general practice of smashing of Irishmen's windows. Any actual window-smashing beyond this requires a new intention. Thus I have, indeed, done an act, and its intention is clear: to encourage the smashing of Irishmen's windows. But the smashing of Irishmen's windows is merely a velleity. I am not trying to smash them myself; nor am I formally cooperating with any act of window-smashing. I'm merely providing the materials for window-smashing and hoping that people act on them.
I don't think the inciter is the primary agent in these cases of incitement. The inciter is certainly an agent: he's an advisory cause. But he's not the primary agent, because he's not the one primarily giving the act form. The person who actually commits it is the primary agent; the inciter is a secondary agent, someone who facilitates the acts of the primary agent. The inciter is the guiltiest of the bunch not because he is a primary agent for anything (except incitement) because deliberate incitement to wrong action is, in and of itself, very, very serious. It is what is called the sin of scandal. If I deliberately incite you to murder John, you have committed a very serious sin, that of murder. But I, having worked to destroy your soul and contribute to the murder of John, have committed a worse one. That's how serious the sin of scandal is.