Thank you for sharing this question from your recent conversation. I empathize with your conversation partner quite a lot, agreeing that we do not (and can not) know everything about everything! As many people have said before, “We don’t even know what we don’t know!” Indeed, God and his universe are vast. But does this foreclose our ability to know truth? (And are truth and knowledge the same thing?)
These are important questions in the branch of philosophy known as epistemology. They are some of the questions that interest me most, as I often find them at the root of people’s various apologetics questions: what counts as proof? how can we know?
One of the most helpful things for me has been realizing that in Western culture (and many other places to which Western thought has been exported) our epistemology has been formed by the ethos of the Enlightenment. We hold up the mathematical and physical sciences as the ideal of knowledge. If we have trust any authority, take anyone else’s word for it, or in any way trust…then it falls short of knowledge. We think of knowledge as mathematical certainty. All variables must be known. But is everything known in this way?
It is a well-established counter to this claim that historical knowledge is not known in this way, and we believe that we can have genuine knowledge of past events. So what else is known in ways unlike science? People, for one. We do not know someone by having comprehensive schematics of their body and chemical make-up, and a catalog of their demonstrated preferences. We know them though experience, but most of who they are we have to take their word for: they self-disclose, or reveal themselves to us. Persons are simply not knowable in the same way as, say, toasters or chairs. We can analyze their organism in that way, but the person remains hidden by those means. So some knowledge is simply of a wholly different kind than what we demand of math or the hard sciences. Their method is not the ideal for all objects of study. What something is determines the methods by which it can be known (as philosophers such as Roy Bhaskar have pointed out). All this to say that certainty is a tricky word and we would do well to evaluate what we are asking for when we demand it.
If we can’t be sure of anything until we have explored everything, as your friend suggests, then we would have to remain permanently agnostic about everything. Is that a tenable position? More pointedly, is that how we really live? I would argue that it is not. Everyday we live assuming the truth of a hundred things we personally cannot prove. We actually live in state of dependent trust, despite all our big talk about thinking for ourselves and firsthand empirical knowledge. We are prone to say, “I only trust science.” But in fact, we trust scientists, because most of us are not specialists and we must take scientific findings on authority.
That has been the most significant factor in my conversations on epistemology: the realization that we all place our faith in someone. No one relies on pure and naked knowledge. Everyone trusts someone. This significantly levels the playing field in epistemic conversations where faith and knowledge are posed as alternatives. In fact, faith is prerequisite to knowledge, as St. Augustine has argued (in Against the Epistle of Manichaeus Called Fundamental and elsewhere). I believe that Leslie Newbigin is correct that the Christian aim for knowledge is not a quest for mathematical certainty (besides in math!) but for “proper confidence.” His slim book by that title is well worth reading and I highly commend it.
My thinking about the nature of knowledge and truth—especially as relates to our philosophical and religious claims—has been greatly helped by several thinkers including Augustine of Hippo, Michael Polanyi, Esther Lightcap Meek, and James K.A. Smith, among others.
Two slim reads (only 100 pages!) that are both excellent—especially for beginners on this question or those new to this perspective on epistemology:
What further questions do these thoughts on knowledge and certainty raise? How do you think your friend might respond to the idea that it really comes down to each of us choosing who we will trust?