In strict opposition to the prevailing positivist conception of nature as senseless and deprived of meaning Jakob von Uexküll claimed that a certain planmässigkeit was operative in nature. This idea however might be taken to mean that organic evolution is not itself a creative process but a gradual, if majestic, unfolding of Nature's own master plan. Such an idea would threaten to restore determinism in the center of biological theory, and this would seriously contradict the vision of biosemiotics shared by most of its proponents. It lies at the heart of biosemiotics and of Peircean cosmological philosophy that indeterminacy is primary, that “habit taking” or interpretation are real processes in the world, and therefore that belief in the law of necessity is unfounded. It is suggested that Uexküllian planmässigkeit is in fact reconcilable with a modern non-deterministic understanding. In a certain sense the Umwelten of animals have indeed developed in accordance to a natural planmässigkeit, but this is a plan that incessantly traps life in certain strategic choices and in the same time diversifies the dimensionality of options for dealing with these choices, i. e. “the adjacent possible” in the terms of Stuart Kauffman.