Economists (most of them) build their models assuming most of the time _stochastic dynamic equilibrium_. So Economics does not contrast "dynamic" with "equilibrium" - it synthesizes them.  

It is stochastic in the sense that random shocks are acknowledged. It is dynamic in the sense that it may revolve around a deterministic or stochastic trend. And it is an equilibrium because, exactly, it is assumed "chained" -not necessarily to some _level_ but at least to some trend.

The "bias induced" here, the price to pay, is that mainstream economic models are not very good at predicting derailment and crises. On this, perhaps it would be useful to read [this column article][1] by well-known economist [Robert Lucas][2].


  [1]: http://www.economist.com/node/14165405
  [2]: http://www.nobelprize.org/nobel_prizes/economic-sciences/laureates/1995/lucas-bio.html