Ceteris Numquam Paribus

You can't step into the same river twice.

   Forecasting the economy is like forecasting the weather. There are many variables, and they can change by the hour.
   Weather analysts consider temperature, wind strength and direction, humidity, and atmospheric pressure within a given regional weather system, plus the proximity of one system to another. That makes for six primary factors, all of which contribute to possible precipitation, and the possible combinations border on the infinite.
   There is also, of course, climate, where one or several of the primary factors -- temperature, for instance -- stays in a given range for an entire season. Weather, on the other hand, changes daily, even hourly, making forecasting a challenge. In short, weather forecasting is not an exact science.
   Neither is the study of economics. It is a social science, along with anthropology, sociology, psychology, and even marketing. No one would claim that in business, marketing and advertising are exact sciences, like chemistry or physics.
   In the social sciences, there are impulses and trends that can be documented, and -- assuming a trend continues -- an event can be predicted.
   Just so with weather and economics. Life is a series of if-then statements, based on assumptions that are sometimes heroic.
   Computer programmers know well the pattern: If this, then that. Parents also use it on children: If you do this again, then you will get spanked. Also, if you touch this hot stove, then you will get burned and it will hurt.
   Weather forecasters, after getting smacked down by a fickle Mother Nature last week in the New York City region, have since lowered their confidence levels and have emphasized the variables and possible alternate outcomes while showing their graphic models of what might happen if, if, if and if.
      Economists have long used the ceteris paribus (other things equal) assumption in their forecasts. If other things remain equal and nothing else changes, then we can expect such and such will happen.
   In the real world, however, other things never remain the same for long. They may hold steady for a time, but people can be as changeable as storm systems generated by Nature.
   Meteorologists can be confident of their short-term forecasts, but long-term weather forecasts are at best a gamble. This is not to be confused with climate change, which is itself the study of long-term trends. Economists, also, deal with reasonable confidence levels when talking about short-term trends and predictions. But when it comes to longer economic predictions, as John Maynard Keynes put it, "In the long run we are all dead."