QUOTE : What are we to do at any given moment, when we cannot say which of our current claims will be sustained and which will be rejected? This is one of the central questions that I have raised. Because we cannot know which of current claims will be sustained, the best we can do is to consider the weight of scientific evidence, the fulcrum of scientific opinion, and the trajectory of scientific knowledge. This is why consensus matters: If scientists are still debating a matter, then we may well be wise to “wait and see,” if conditions permit.26 If the available empirical evidence is thin, we may want to do more research. But the uncertainly of future scientific knowledge should not be used as an excuse for delay. As the epidemiologist Sir Austin Bradford Hill famously argued, “All scientific work is incomplete—whether it be observational or experimental. All scientific work is liable to be upset or modified by advancing knowledge. That does not confer upon us a freedom to ignore the knowledge we already have, or to postpone the action that it appears to demand at a given time.”27 At any given moment, it makes sense to make decisions on the information we have, and be prepared to alter our plans if future evidence warrants.