In light of several comments on a recent article onthe pointlessness of antibacterial soaps, it seems as though a more complete discussion of cost-benefit analysis might be useful. It is a process that is useful in many aspects of biology, from resource management to health issues.
The basic premise is that to make decisions, you need to estimate both qualitatively and quantitatively the potential costs and benefits of the possible choices, and use that information to make the best choice. The magnitudes of both cost and benefits are important, because balancing a large cost against a small benefit will result in a different choice than when the cost is small but the benefit is large.
The mistake most people make when making choices is to consider only the potential benefits, or the costs, but not both simultaneously. For example, the anti-vaccine movement exists mainly because of fears of side effects, specifically autism (a link which has not been established). Yet even if all the potential side effects do occur, they are extremely rare, relative to the benefit received in resistance to disease, many of which can be fatal. True, if only a few school children are unvaccinated they may get by given that disease is less likely to travel through a group that is mostly vaccinated. But this cheating can be harmful even for some vaccinated children, for vaccines that are not 100% effective (such as whooping cough).
The point is that to focus on a vanishingly small cost to vaccination which confers a huge benefit in protection from common disease is a completely irrational choice.
Another context where cost-benefit analysis applies is in the area of climate change. Here, the problem is a bit tougher, because the costs and benefits of trying to do something about it, versus not doing anything, are harder to estimate. One major consideration in this case, of course, is that we only get one chance to do something (and the opportunity to do it may already be vanishing rapidly). We don’t get to figure out what we did wrong this time and fix it the next. So what do we do? We first must acknowledge the possibility that climate change could be catastrophic, no matter how small. This is a potentially huge cost to ignoring the issue. The benefit to ignoring it is easier to grasp – short term economic pains in readjusting our energy usage around the world, which is clearly a monumental task, would be avoided.
The benefit to doing all we can to avert a possible worldwide catastrophe is two-fold; first, we potentially save a lot of the planet, and second, many of the measures taken could have positive geopolitical results as well, e.g. reduction in demand for oil, and spurring economic growth in new alternative-energy industries. The cost mirrors the benefit for not doing anything – it is the difficult inertia needed to radically change the way we produce and use energy. The biggest part of the problem in looking at these costs and benefits is that if we choose to do something, the costs are biggest here and now, while the benefit seems far down the road. Most of the people setting policy in the powerful industrial countries that could take a stronger lead on this will likely be dead before the jury comes in on the outcome.
This video goes into more detail about these trade-offs, and convincingly makes the argument that the eventual benefits of doing something now outweigh the costs.
A similar case involves the control of invasive species. Even though most of the time the benefit in controlling them early far outweighs the potential cost of doing nothing, and having to control them later, we still tend to ignore them until they are too late to control. The reason for this is that our political system for government (which is responsible for making and acting on these decisions) overly discounts future benefits. So, time after time, we wait to see whether an introduced species gets out of control before we do anything to control it, and end up spending millions more than it would have cost to control it early on.
Another health example is cancer treatment. With all the progress that has been made, we still know very little about what we are doing in this area. In this case, people tend to focus on hoping for a strong benefit, and accept all sorts of hellish treatment (a significant cost) that may or may not benefit them. But this is one case in which it is very difficult to be objective, because we are dealing with our own mortality, and we buy into the idea that anything that can possibly help is worth doing. Is it possible to make a rational decision? For some people it is, but they are in the minority.
And come to think of it, it is way too much to ask the multi-headed government beast to be rational too. At least it is easy to make the rational choice about anti-bacterial soap.