Notwithstanding these subtle differences, as fallibilistic scientific philosophers seeking to cut a discerning path through various schools of rationalism, idealism, and empiricism, upon which they deeply drew in their respective syntheses, Dewey and Popper were closely in sync on the core assumption that:

Every solution to a problem raises new unresolved problems; the more so the deeper the original problem and the bolder its solution. The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance. For this, indeed is the main source of our ignorance-the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite (Popper, 1963, p. 38).

In their divergent ways, Dewey and Popper pressed hard against this goad in seeking truth, if only as a regulative ideal, through rigorous scientific methodologies for the purpose of learning important things about the world and changing some portion of it, however piecemeal, for the better.

Objective Knowledge: An Evolutionary Approach

While rejecting the possibility of attaining certainty, Popper argued forcefully for achieving objective knowledge. Such an attainment is possible as a result of the rigorous work of formulating best-case bold conjectures and subjecting them to severe tests. This refining process of critical inquiry is stimulated by the infinite gap between any current attainment of knowledge and what might be achieved as a result of new insight and information gained in the struggle to work out problems that challenge humans to push beyond the boundaries of given understandings, even while necessarily building on what has been previously learned. Popper noted that any new knowledge gained remains a conjecture, and therefore open to ongoing analysis even as falsification closes certain doors, at least until further notice, so that the theories that remain are viable candidates as truth propositions even though the veracity of such a claim cannot be positively ascertained.

Motivating Popper was the desire to press against the specter of relativism that knowledge gained can only be categorized as a perception in which, in principle, any interpretation is as valid as another in terms of its truth content. In this respect he argued that human knowledge grows through the process of trial and error in the pursuit of probing questions and problems that stimulate the imagination even as such knowledge gained remains invariably fallibilistic. Consequently, Popper acknowledged the gap between the finitude of human cognition and truth as a regulative ideal defined as correspondence with the facts. In stressing the possibility of getting closer to the ideal, he maintained that any notion of "closer" is a metaphor that stands for our best striving, which nonetheless cannot close the perpetual disparity between the reality and the ideal in any absolute sense given the unending human capacity to transcend any current understanding. Thus, Popper pointed to a realistic metaphysics undergirding his epistemology that he could not prove, yet one essential on his reading to situate a view of scientific knowledge, which if either indeterminism or the possibility of science as a disciplined body of logical analysis were closed, the enterprise of human growth would be curtailed.