The point of forecasting is not to attempt illusory certainty, but to identify the full range of possible outcomes. Try as one might, when one looks into the future, there is no such thing as “complete” information, much less a “complete” forecast. As a consequence, I have found that the fastest way to an effective forecast is often through a sequence of lousy forecasts. Instead of withholding judgment until an exhaustive search for data is complete, I will force myself to make a tentative forecast based on the information available, and then systematically tear it apart, using the insights gained to guide my search for further indicators and information. Iterate the process a few times, and it is surprising how quickly one can get to a useful forecast.
Since the mid-1980s, my mantra for this process is “strong opinions, weakly held.” Allow your intuition to guide you to a conclusion, no matter how imperfect — this is the “strong opinion” part. Then –and this is the “weakly held” part– prove yourself wrong. Engage in creative doubt. Look for information that doesn’t fit, or indicators that pointing in an entirely different direction. Eventually your intuition will kick in and a new hypothesis will emerge out of the rubble, ready to be ruthlessly torn apart once again. You will be surprised by how quickly the sequence of faulty forecasts will deliver you to a useful result.
This process is equally useful for evaluating an already-final forecast in the face of new information. It sensitizes one to the weak signals of changes coming over the horizon and keeps the hapless forecaster from becoming so attached to their model that reality intrudes too late to make a difference.
More generally, “strong opinions weakly held” is often a useful default perspective to adopt in the face of any issue fraught with high levels of uncertainty, whether one is venturing a forecast or not. Try it at a cocktail party the next time a controversial topic comes up; it is an elegant way to discover new insights — and duck that tedious bore who loudly knows nothing but won’t change their mind!