There are two traditional ways to structure a proof:
1). By citing examples, and
2). By disproving the opposite
While in statistics and epidemiology we favor the second, I will step away from this in favor of the first method and will explore a relevant example. Since I am still reading Devra Davis's book (see my recent post), the example will come from the world of cancer.
Let's take breast cancer, for example. Your counter-argument to my statement is probably that mammography is the perfect example of how health promotion can turn into a viable business model. OK, let's examine our assumptions. The central assumption here is that mammography is indeed a health promoting technology. What we hear is that early detection saves lives, so we encourage all women at around age 40 years to begin with annual screenings. And look, the proof is in the pudding: survival with breast cancer has improved dramatically over the last 2 decades. But is this really cause and effect? Most data do not support the idea that mammography decreases cancer mortality. Indeed, among younger pre-menopausal women the usefulness of mammography has been questioned by several reputable groups. Younger women's breasts are dense and are prone to high false positive rates of mammographic findings. These then have to be followed up with additional tests, such as an ultrasound or even an MRI with contrast (costly interventions beget further even costlier ones). On occasion, the only way to rule out a malignancy is through surgical excision -- you have to agree this is a very high price to pay for a diagnosis of a benign breast lesion! Sometimes, however, a very early cancer will be diagnosed and excised,which is potentially life-saving, right? Well, this is not so clear either, as scientists are beginning to conclude that many of the very early ductal carcinomas in situ, or DCIS, are probably subject to the woman's own immune extermination and do not develop into life-threatening aggressive disease. So, at least there is no lasting harm from screening mammography beyond the short-term physical and emotional ordeal, so the benefit still outweighs the risk, right? Not so fast. Since mammography exposes a woman to a dose of radiation, albeit small, there is reason to question whether mammography itself may be cancer-causing in some individuals.
I do not want to sound cavalier and suggest that we all quit getting our annual mammograms. What I am suggesting is that each of us take the time to learn about the data and discuss them cogently with our healthcare providers in order to make the most sensible individual decisions. At the same time, we need to acknowledge that there is no free lunch. What I mean by that is that early identification (typically through the utilization of costly technological interventions) does not equal prevention (typically through identification and systematic avoidance of potentially causative exposures). Even the language implies the economic consequences of each -- revenue generation through utilization and revenue loss through avoidance.
Many of the same concepts can be applied to structuring arguments in other areas of healthcare interventions, but I will not belabor this point now. The bottom line is that the less we think we need, and this includes cars, television sets, soda, the less potentially detrimental disease-causing environmental exposures we may subject ourselves to. But, of course, at the same time, the worse our 401Ks will perform. So, once again, the choice is ours -- health or wealth?