Those who wish for permanence in classifi cation must pay the price of stasis - as if for ever condemned to confound whales with fish. M. T. Ghiselin 1981, p. 283 Scientific argument is a debate concerned with the solution of unresolved problems. Before continuing with the phylogenetic system of the Metazoa this foreword gives me the opportunity to discuss some controversial ques tions, to state selected positions more precisely and to remedy omissions. I would like to draw special attention to serious problems for phylogenetic systematics resulting from the inevitable confrontation with the...

Those who wish for permanence in classifi cation must pay the price of stasis - as if for ever condemned to confound whales with fish. M. T. Ghiselin 1981, p. 283 Scientific argument is a debate concerned with the solution of unresolved problems. Before continuing with the phylogenetic system of the Metazoa this foreword gives me the opportunity to discuss some controversial ques tions, to state selected positions more precisely and to remedy omissions. I would like to draw special attention to serious problems for phylogenetic systematics resulting from the inevitable confrontation with the...