The unknown mechanism of action of the IUD

A fellow philosopher just sent me this very interesting quote from an article in a reputable medical journal:

[I]f it was conclusively shown that the sole or principal mode of action [of the IUD] was to prevent the embryo from implanting, then this method, as in the case with emergency contraception, would be considered by the Roman Catholic church as causing an early abortion. As a result many agencies involved in the research, development or delivery of contraception prefer to leave the mechanism of action issue unresolved, which may explain why research into the contraceptive mechanisms of IUDs has been sparse in the last 20 years.

The quote’s invocation of politics fits with vague suspicions I had.

But in any case, I wonder whether leaving the “the mechanism of action issue unresolved” helps all that much morally. Suppose that prevention of implantation is morally on par with paradigmatic cases of killing an adult human. Now consider this story. You are a doctor on board a spaceship marooned on an alien planet. All your drugs have been destroyed but one of your patients is suffering severe pain. The aliens have a callous attitude to human life, but in exchange for a piece of fine art they offer you a drug. The aliens always tell the truth and they guarantee that the drug “terminates the pain.” But when you ask them about the mechanism by which it does so, they say: “Trade secret. It terminates the pain.” You try asking more general questions like: “Does it suppress pain signals in the brain?” They just say: “That would terminate the pain. It terminates the pain. Why ask more?” Then someone else in your crew asks: “Does it terminate the patient?” And the aliens say: “That would terminate the pain. It terminates the pain. Why ask more?”

The end result is that you have no idea whether the drug terminates the pain by suppressing the pain as such or by killing the patient. It is clear that in that case we should not use the drug, except as a last-ditch hope for a patient who is already dying. (I am not saying it is acceptable to kill someone who is already dying. But if someone is already dying, then one can tolerate a greater risk of unintended death.)

I am not saying, of course, that we need to find evidence against every crazy hypothesis. There is, after all, the hypothesis that ibuprofen works by annihilating the patient and calling in aliens that replace the patient with a pain-free simulacrum. The tiny but non-zero probability of that hypothesis should not keep us from using ibuprofen. But when we do not know how some drug or procedure works, and one of the serious hypotheses is that it works by killing someone, then that’s a problem.

Given the callousness of the aliens, the hypothesis that they are offering a euthanasia drug is a serious hypothesis. Likewise, the hypothesis that the IUD works primarily by preventing implantation is a serious hypothesis (see the suggestive evidence in the above-quoted paper). In both cases, then, unless we can find significant evidence against this serious hypothesis, the use of the drug or method is wrong (except perhaps in exceptional cases).

We rightly have a guilty-until-proved-innocent approach to medical interventions. Apart perhaps from exceptional cases (e.g., terminal ones), a medical intervention must be tested for its effects on the directly affected parties. The manufacturer's failure to gather data on the effects of the IUD on some of the directly affected parties, namely the embryos, means that the IUD has not been tested up to the morally required standards of testing medical interventions, and hence cannot be licitly used (apart perhaps from some exceptional cases), even absent the data that we have that is suggestive of fatal effects on those parties.