  We propose a uniform method of constructing ultrafilter extensions from
canonical models, which is based on the similarity between ultrafilters and
maximal consistent sets. This method can help us understand why the known
ultrafilter extensions of models for normal modal logics and for classical
modal logics are so defined. We then apply this method to obtain ultrafilter
extensions of models for Kripke contingency logics and for neighborhood
contingency logics.
