When many philosophers speak about epistemology, they speak about how we know things and how we provide justification for what we know, and quite a bit of this epistemological work is spent on a certain kind of knowledge. This knowledge is the kind of knowledge that we articulate (make explicit) when we say a thing propositionally, like I know that January is the first month of the year in the US.(1) Such propositional knowledge is also sometimes referred to as know-that knowledge, and is often structured in a particularly grammatical way, at least for demonstration and analysis: e.g., S knows that P, or a subject knows that predicate.
Knowledge under such a view is generally defined as justified true belief (JTB). The description is nicely stated in the SEP article linked to above, but in short, we can only know things that are true (T) and not things that are false, we can only know things that we believe (B) and not things we do not believe, and we can only know things if we have justification (J) for them and not know things by luck. If all of these conditions are sufficiently met, then we have knowledge of the know-that type. For example, if we fail to meet the condition of belief that January is the first month of the year in the US (i.e., we do not believe that January is the first month of the year), then we do not carry that knowledge around with us. Or, that is knowledge we do not have, even if it is true, even if there is justification for it, and even if we are aware that such a proposition has been made by others (we might believe they are lying to us).
Polanyi does not ignore know-that (explicit) knowledge. In fact, he clearly states that this kind of knowledge and the kind that he is interested in discussing (tacit knowledge) are strongly intertwined, but he is primarily interested in understanding the latter (know-how) because he thinks it is important in understanding science, what science is, and what makes good science. We will come back to more of this science issue later.
In the meantime, this background information is important to have when learning about tacit knowing and knowledge. This is because it helps provide some understanding of how knowledge is understood, analyzed, and researched in a certain way in the knowledge management literature, which rests upon, often without attribution (see McCain on Obliteration by Incorporation), Polanyi's concepts. Most of that literature (that I have read, at least) does not address tacit knowledge in much detail but to say that it exists and to posit ways in which it can be converted into explicit, codified knowledge, if it can be.
Let us reflect on what Polanyi is then doing in this first lecture from The Tacit Dimension. Polanyi articulates four aspects of tacit knowing: functional, phenomenal, semantic, and ontological. We will address the last three later, but it is important to spend a bit of time on the functional aspect because it is very key to understanding the rest.
The functional aspect lays out how we know a thing tacitly. Specifically, we know a thing tacitly by attending to some related, explicit thing. His example: people who are given electrical shocks when presented with certain nonsense syllables know when to expect the shocks even when they cannot say what specific nonsense syllables are triggering the shocks. That is, they attend to the shocks and by attending to them, attend from the particulars that cause them (the nonsense syllables). This attending from is still anchored to the particulars (the nonsense syllables) and so there is a relation. That is, the particulars are indeed known in this attending from. How else, Polanyi argues, would subjects in this test know when to expect the corresponding shocks? But even though the subjects know the particular nonsense syllables that trigger the shocks, they can not tell so explicitly (in their minds or verbally). They know more than they can tell.
One of the key ways that I have thought about this relation and how it fits within the knowledge management literature is by thinking about the process of writing computer programs. In this process, the computer programmer must (tacitly) make things explicit when writing instructions so that the computer can correctly execute the software code. If the programmer fails to be explicit in writing these instructions, often painstakingly explicit, then the computer will not be able to process those instructions. Unlike people, computers, then, seem to be purely explicit-knowledge-machines. They are, apparently, entirely dependent on know-that knowledge and on the functional and other relations that compose that type of knowledge.
Yet, facial recognition, autonomous vehicles, and robots that walk, jump, and flip seem to challenge that analogy simply because these abilities require a different sort of software instruction that cannot be all explicit or codified. Remember that Polanyi uses the facial recognition example to explain tacit knowledge, but if computers are capable of recognizing faces, and they do so without detailed propositions about the structure of all human faces on the planet or that will be on the planet in the future, then they either must not be explicit-knowledge-machines, or there must be a way of converting all tacit knowledge into explicit knowledge. If the latter, then Polanyi is not correct and we can tell all that we know even if we have not yet told everything that we know.
There is more to this though. The functional relation in tacit knowing is only one of the relations. There is still the phenomenal, the semantic, and the ontological to deal with, and we must still reckon with the very prescient discussions about the body and about dwelling that Polanyi writes about---discussions that will have some major implications on topics such as human computer interaction and other practical, applied issues. Thus -- to be continued.
(1): Amartya Sen addresses this background work nicely in the preface to the Tacit Dimension.