The bio-physicist, cyberneticist and significant representative of radical constructivism doubtlessly falls into the trap he has so rightly set up himself: the above quote claims to be true and not to be a contradiction.
Nonetheless, this short sentence is convincing because so many religious wars or wars between allegedly national identities are based on the desire to enforce something seen as irrevocable truth. Indeed: it is only through war that the belief in truth gains ground. Otherwise, truth is unsustainable. And, von Förster should have appreciated this contradiction because in radical constructivism there is no such thing as the compliance of the perceived image with reality (whatever the latter may be). Hence, instead of objectivity, there is only entirely subjective perception.