The concept of philosophy as rigorous science has a postulatory and programmatic character: Husserl wanted to realize such a philosophy and was convinced that its realization was possible when and only when philosophy became eidetic knowledge about pure consciousness and its intentional correlates obtained in immanent eidetically attuned perception. This postulate can either be accepted or rejected, but its advancement — in itself — seems not to entail an idealistic solution of the problem of the existence of the world. It is possible to doubt the Tightness of the premises on which this postulate rests e.g. the assertion about the existence of immanent perception and about its indubitability or correlatively the assertion about the principal dubitability of a direct cognition of the external world. It can also be doubted if philosophy is to obtain "absolute" indubitable knowledge instead of being satisfied with knowledge of the same cognitive value as e.g. the natural sciences are entitled to. Why demand something more from philosophical knowledge?