But once the naked truth stands revealed before our eyes, we have the power to see it, to distinguish it from falsehood, and to know that it is truth. Karl Popper, Conjectures and Refutations, Rutledge, 2nd ed. page 7
Popper thinks the idea that the truth is manifest, that we can read the book of nature or, is a bad idea that nonetheless contributed to a lot of good.
The brief story is that the doctrine of the manifest truth was used by Renaissance thinkers to reject authority, and hence liberate humanity from the yoke of dogma and superstition. Take no one’s word for it became the motto of the Royal Society, and this lead to an explosion of knowledge and rapid improvement in human wellbeing. Awesome.
Instead of relying on the priest or the shaman, people can discover the truth for themselves simply by looking. Certainly, we need to shed our prejudices and our biases (see today’s incarnation via the focus on cognitive biases), and we may need ever more elaborate tools of science and big data, but if we look hard enough and in the proper ways, the truth will reveal itself to us. Call it empiricism or intellectualism, this outlook has remained dominant to this day.
Popper showed that the doctrine of the manifest truth is wrong because it implies an ultimate, fundamental source of knowledge — either observation (Bacon’s empiricism) or untainted reason (Descartes’ “I think therefore I am). However, we can always ask of a fundamental source, “how do we know?” To this, we must supply some reason, which again is subject to questioning, ad infinitum. (For a more detailed refutation, see page 27.)
Any search for an ultimate source of any fact or theory leads to an infinite regress. Therefore, there can be no ultimate sources of knowledge. By positing that observation or pure reason could undergird the tree of knowledge, Enlightenment thinkers simply replaced the authority of the church with the authority of empiricism or rationalism.
This was a giant step forward for human progress, but it was not a great advance for our understanding of how we know what we know. Unfortunately, most contemporary thinkers remain mired in this philosophy of authority. In fact, there are no ultimate sources of knowledge.
Next up: The conspiracy theory of ignorance.
The above point is really quite simple, as it can be demonstrated by a three year old who simply doesn’t have enough sense to stop asking “why.” Yet, its consequences reach into almost every aspect of modern life.
To see this, pay attention to how often a statement or theory is justified according to its source.