Many fuzzy reasoning methods do not consider temporal information, eve
n though time delays are an inherent part of many kinds of information
exchange. We propose, therefore, a method of dynamical fuzzy reasonin
g that has a time delay between premise and consequent in fuzzy rule-b
ase knowledge. In this paper, we consider this reasoning method qualit
atively and show how to apply it to system models whose basis is Syste
m Dynamics.