Great user interfaces operate at a tacit level. The hands work without verbal instruction, to manipulate the objects on the screen.

In this sense, the interface becomes an extension of the body. We do not have to give verbal instructions to the parts of our body to make them do what we want — at least not once we’ve mastered a movement.

When we work to learn a new movement, it is as if the tacit mind transfers control to some other verbal part of the mind that clumsily operates the movement while the tacit mind works to understand in its own kinetic way so it can take over. And when it takes over, the verbal mind must get out of the way. If it remains in control — even a little — its verbalizations will get in the way and trip the tacit mind up. As a teenager I read a dirty trick from The Inner Game of Tennis on how to destroy an opponent’s serve: ask for an explanation on how the serve is done. Instantly the serve stops working, and the opponent falls into a vicious down-spiral of frustration and attempts to analyze and fix the broken serve.

So when software gets in the way of our hands and requires a shift of attention from the work to the operation of the software, it is a profound and frustrating shift of consciousness that makes any work that requires concentration and flow fall apart.

The more a person’s work requires flow, the more frustrating it is to have the flow broken by verbal interruption. Worst of all is when a piece of software has been mastered, the tools becomes an extension of the body and the mind, and flow has become easy — and then the software is changed in a way that requires retraining of the tacit mind. Suddenly, an impediment  breaks the continuity of thought and motion and effect, and the flow is no longer accessible. Then, not only is there a difficulty — there is an irrecoverable loss of a mode of activity, a violation of hard-won mastery.

Sometimes the change is worth it. It is an investment. The retrained tacit mind works even better than before. But this is not always the case. Sometimes what motivates the change is a personal aesthetic preference of a designer or product manager. Sometimes the change is made to accommodate more kinds of tasks and users. Sometimes the change is made to make room for more features, added for the sake of demonstrating innovation, or having a bigger feature list to whip out to impress customers and humiliate the competition.

In all these cases, someone is thinking about the software as something that is looked at, noticed, thought about and evaluated. Great software, however, disappears behind the actions it supports, as a great sentence disappears behind its content.

With sentences and software a compulsion to stand out, to make an impression, to be thought of as great creates annoying mediocrity.

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Great software disappears behind the actions it supports, as a great sentence disappears behind its content.

The goal is flow, and flow requires tacit mastery of the tools one uses. Tacit mastery is fluency.

We usually use the word fluency for mastery of language. And what this means is we are no longer verbally operating the foreign language with our verbal mind. The tacit mind has stepped in and works with the new language directly.

So, really, it is not a tacit mind or a verbal mind. It is always the tacit mind — the tacit mind extending itself through fluent mastery of tools. And one of the most powerful and flexible tools is language. With the tool of language the mind can extend itself to all kinds of other tools, by asking itself questions, making tactical plans, and executing on those tactical plans.

Some people seem only to master this mode of activity. It is probably a great investment and a winning strategy — learn the one tool and use it for everything. But working exclusively through language does limit what can be done beyond the limits of language.

And what are beyond the limits of language? As-yet-inarticulate possibilities. To work through language — to only think or do what one already knows how to say does not entirely preclude innovation, but it does hobble it considerably.

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In reading difficult books, especially philosophy books, a mind is learning fluency in new language tools. Sentences, paragraphs, chapters — the whole book — the whole corpus, even — must be read and reread from different angles until the words hang together and make a whole fluid meaning. The tools are learned and then they are used, but there is not always a nice verbal link between the before language and the after. It would be like showing how to use a hammer by operating a screw-driver.

Most of us choose to read books that make use of pre-existing fluency for effortless consumption, or to build upon the old mastered language and extend or refine what already was. Philosophy, however, breaks your serve.

But often, as with software, we have to ask why. Why would you break my existing tacit understanding? Is it a good investment? Will you help me think better? Or are you building your list of publications to impress colleagues and intimidate rivals? Are you moved by the work, or the need to compete?

Great philosophy disappears behind the thoughts it conceives.