Immanuel Kant, who revolutionized the philosophy of his time, famously wrote that his was a Copernican Revolution. Just as Copernicus had radically revised the then existent picture of our universe, pointing out that the sun, not the earth, was the center of things, that we revolved around it rather than vice versa, so Kant believed his approach to philosophy radically refashioned how it would be done henceforth. And on the evidence, he was right. Kant moved philosophy from the metaphysical project of trying to describe the world comprehensively, in all its aspects—by applying our epistemic capacities to things beyond our empirical reach—to describing what we can think and know about what is the case and limning the rest indirectly, by sketching out what must also be the case if we are to know anything at all.

This is no less metaphysical than our efforts to talk about what lies beyond our intellectual reach, of course, but it isn’t subject to the inherent error of attempting to describe what is, in its nature, necessarily indescribable. Hence Kant concluded his efforts were of a "transcendental" nature, his metaphysics understandable as a transcendental sort albeit without assuring us of the same level of epistemic result we expect from knowledge obtained through the senses, from information garnered about things that can be seen or felt, etc. After Kant philosophy turned much of its attention to the parameters of knowledge itself. Kant, himself, sought to explain the seeming reality of things, and our capacity to know that reality, by explaining how this world is ultimately just a product of our human minds. We are, he reasoned, in possession of certain mental equipment which gives form to the bombardment of information we receive on an ongoing basis, shaping it through a kind of built-in lens into a world of things we see and feel, hear, smell and taste, the sensory data impinging on us being shaped, as it were, into knowable phenomena, things we can identify as such and so speak about. Our sensory organs, he reasoned, in tandem with the shaping capacities inherent in our minds, make of the raw data something shaped and structured, yielding objects for our attention where, before, all was disparate and unconnected, unformed, amorphous.

But we cannot, he thought, know the structures within which knowledge as such takes shape in the same way we know the things shaped. These structures or forms consist, he concluded, of our ideas of space, time, causality and so forth. They are not discovered in the world because they aren't things awaiting an observer's observation. They are, rather, the forms of things which are imposed on the world by ourselves. Presumably for other kinds of creatures there could be other types of worlds shaped in different ways than ours—even if such creatures exist side by side with us and move about in the world we recognize as ours—the sort that is spatially, temporally and causally determined. The real world however, Kant tells us, the one underlying the shaped world we know as ours, is not itself knowable. What we take the world we see to be is just appearance, informed by the structures inherent in the minds of creatures like ourselves. It's what we make of the stuff impinging on our sensory apparatus in order for it to make sense to us. What is really going on though, what lies behind or beneath those appearances, he called noumenal, as opposed to the phenomenal which is our world. And this noumenal domain is simply unknowable—a blank place for human knowledge though it is presumptively there—or else where do all our sensory impingements come from?

For Kant there is nothing intelligible we can say of this noumenal domain, the noumenon, other than the fact that we can't know anything more about it than that it's there. If we could, after all, it would be part of the shaped world of phenomena. But then what lies behind that, what could be the source of it? After all, everything that is must have some source? Isn’t causality, itself, a form of our own capacity for knowing, for having any knowledge at all? Neither philosophers nor the rest of us can have access to what lies beneath (though fiction writers may make things up about it and sometimes even tell very compelling stories concerning it). The world we have, on this Kantian view, is one of appearances not reality. The real is noumenal even if we typically take the appearances that demonstrate stability in our world, and causal effect, to be what we call “real.” But what, then, can we hope to know for sure about our world? Only the forms of judgment which we recognize as the shapes imposed by us on the incoming sensory information, giving it an appearance comprehensible to ourselves. We don't do this consciously, of course, but automatically, our brains doing the work unnoticed by us. Yet it is work we must presume to be performed since the world we have (of which we can have knowledge) is always structured according to the intuitions Kant maintains we have of space, time, causality and a number of other relational capacities. If space is the way in which we organize observed phenomena and time the way we recognize its occurrence (in sequence, with befores and afters) then causality must be the necessary means by which we make sense of such a world writ in terms of those two categories, i.e., space and time. Causation becomes necessary because it is how we explain what happens when things bump into one another or change before our eyes. Causality is just the explanatory mechanism which enables our organization of sensory inputs in a structured world. These so-called intuited forms of Kant are not to be understood as mysterious forms of knowledge that intrude on us from outside ourselves in some mystical fashion, nor are they to be seen as "Forms" in the sense in which Plato used the term. They are not Plato's innate ideas, recalled by the soul in order to enable us to fit the plethora of distinct things that make up a disparate reality into general conceptual categories, as if the general categories are, themselves, the templates within which everything else achieves its reality. Rather they are the means by which the unformed takes shape before our eyes. Kant's intuitions are best understood as structure within which empirical knowledge occurs, giving rise to knowledge of a world. And this is just to say to the world as we know it. Kant's categories are not themselves concepts, in the way Plato's are (the Ideal Form of anything into which we can subsume particular instances of it) but the underpinnings of the concepts we form, i.e., they are the rules by which concepts are made possible, derived from our mental apparatus.

Kant's idea about how this works isn't a reassertion of Plato's Ideas, despite the superficial resemblance (both suppose something innate in human beings) but a proposal of structure within which knowledge can happen, but a structure that cannot, itself, be an object of direct knowledge but must be presupposed and treated indirectly. Kant's Copernican Revolution consists of the decision to turn the speculations of philosophy away from what we know of our world (questions concerning its origins, underlying nature, hidden dynamics, etc., that is of traditional metaphysics, at least before Kant) to what we can know about what we know of our world. This reflects his idea that we can think about, and so talk about, the framework that enables knowledge as such, even if we can't study it as we study observables. We can conceptually inquire about its nature and implications through recognizing its necessity for knowledge to occur at all, and by presuming we can deductively draw conclusions about its nature. The fact that it cannot be observed, that we must approach such reasoning indirectly, as it were, is what makes this a "transcendental" rather than an empirical deduction. And the possibility of doing this provides an avenue for a form of metaphysical knowledge which we would not have if we thought knowledge, as such, can only be a function of observation.

But even Kant saw that this method was problematic for if we cannot see anything without looking through the lens of those very intuitions he proposes inform our knowledge of the observable world, the world we want to learn about, then we cannot hope to see the true nature of the intuitions themselves, can we? We must deduce indirectly as it were, for what is transcendental is that because it lies essentially outside the framework of knowing itself. So we cannot say anything substantive about our intuitions in this sense because whatever we say already presupposes their presence, thus influencing what we say. We are reduced here to using the limited language we have to speak about those very limitations.

Here the Kantian picture seems to run aground. How can we even presume to acknowledge the necessary reality of space, time and causality in our world, if we cannot talk about their nature? To the extent that empirical knowledge is observation-dependent (which it is by definition), we cannot have that sort of knowledge about them. So, we must presume another kind of knowledge entirely, a knowledge that is somehow deemed deducible from what we can know, i.e., a transcendental knowledge. But what sort of knowledge is it which cannot be knowledge of anything, cannot have a stateable form? The noumenal world that lies behind (or beneath) the phenomenal one which we see and which our intuited forms, embedded in the structure with which we sort those inputs and so convert them to a world of appearances, would, presumably, be noumenal for any conceivable creature no matter what sort of knowledge-enabling grid it had at its disposal. Kant’s approach assumes a common reality beyond the reach of all knowing cretures. But how can we know it is common to us all if we can’t know anything about it? How can it be outside the knowable world and yet be knowable to us as being there of necessity?

This begins to show the real nature of the problem Kant stumbled onto. For what cannot be said cannot be said, as Frank Ramsey, the Cambridge philosopher and mathematician famously quipped in response to Wittgenstein's somewhat Kantian account of how things are in his Tractatus Logico-Philosophicus, wherein he concluded that "those things whereof we cannot speak, thereof we must remain silent." But even recognizing the inability to speak about what is fundamentally inarticulable, Wittgenstein saw the problem, offering instead of Kantian’s solution of a “transcendental deduction” a notion quite different, I.e., the idea of showing what is rather than talking about it. In the Tractatus Wittgenstein asserts that some things can be shown, as he put it, even where there is no hope of saying anything useful about them. This he suggested offers a way to access the so-called transcendental, among which he placed matters of aesthetic and ethical concern. We access these, he suggests, by presenting or showing what is said or done to others, that is by just doing what we do, even if we cannot speak descriptively about it. Some aspects of human life are simply there, on this account, to be accepted, recognized, expressed. But not to be explained or justified or otherwise put into words.

When presenting for the Wittgenstein of the Tractatus, or, as he put it, showing, replaces the Kantian “transcendental deduction,” we find ourselves no better off for here what is of interest to us is left unaddressed. Where Kant wanted to say something explicit about these forms of our understanding, however generally or indirectly, Wittgenstein’s rejection of the or need for saying anything at all seems to founder as well. Showing may work in matters of acknowledging space, time and causality as aspects of our knowledge which cannot be discarded but when it comes to human activities and the choices that drive them, it leaves us high and dry. In matters like ethics it seems there is still much to be said and, indeed, a need to say it.

Wittgenstein eventually came to discard his notion of showing rather than saying, at least where philosophical inquiry was concerned. Instead he turned to a notion of language as activity, embracing its showing role by pointing out that language is behavioral and enables different forms of communication between its users, showing by its applications in context what it means to convey. Knowledge, on this revised view, consists of how we behave (including what we say to one another). Knowledge is no longer construed as Kant saw it as explicatory. Instead it becomes a matter of the things we do in different situations. It becomes, that is, a kind of pragmatism.

In his later work Wittgenstein shunted aside the issue of showing, construed as a substitute for explaining, in favor of a focus on doing. Don't ask the question, just do what the rules of the relevant language game one is engaged in require. If Kant tried to find a way to distill knowledge from what lies outside it (the "transcendental deduction") and Wittgenstein sought to cordon off language from the transcendent, first by focusing on the unique potency of "showing," as a means of revealing truths we could not otherwise articulate, and later by rejecting the very idea that showing itself answers a genuine question (because there is no question to be asked in the pertinent language game in question, there is just to do what we do), we are still stymied in a philosophical sense. We still want to understand the nature of knowledge and concepts like goodness and truth, don’t we? Sometimes it's just not enough to act within certain rules of practice. We also need to know what acting thus amounts to and how it fits with other things we do as human beings (formulating thoughts, giving explanations, understanding what it is to understand and, of course, choosing the best paths to follow in our activities).

Yet there may be another way to look at this which takes its departure from Kant but moves in a different direction, the one Wittgenstein articulated in his later work. While it is possible to suppose that our brains are configured in such ways as to handle the barrage of incoming sensory information in the fashion Kant describes, another possible explanation stems from Wittgenstein's own later insights about language and how it relates to our knowledge of things. Rejecting Kant’s focus on the abstract notions of space, time and causality, as being fundamental structures inherent in our brains, we can think instead of language, itself, as the human tool or mechanism for knowledge which stands in need of explanation.

Rather than supposing that we have innate structures in the brain that oblige us to see things in space and time and as causally related (a la Kant), perhaps it makes more sense to suppose that space, time and causation are no more than concepts themselves. Rather than intuited forms structuring our thought they are the constructed explanations we create in order to explain a world extending beyond this present moment and place which we inhabit. Here the noumenal realm which drives the world of appearances, is not so much to be seen as a place akin to ours, a kind of parallel domain underlying our domain of space, time, etc., but forever beyond the reach of human knowledge. In fact, we can see it as no place at all but simply as a domain where concepts have no traction. For concepts are, as Kant noted, a function of observers equipped as we, ourselves, are, with a certain cognitive capacity that enables a certain organization of our plethora of inputs.

Absent concepts there are no things as such and so there can be no knowledge at all, for knowledge is by definitely knowledge of something. The world without concepts is noumenal in the sense of being outside our reach but it isn’t one that is parallel to our own, only dark to us. It’s not a world at all. This is not to say such a world, without observers observing it, doesn’t exist, that if there were no observers there would be nothing observable if observers were to be present. It’s only to point out that observing is formative, not depictive—even if, within the framework of our own existence, we can and do portray things to others in a depictive way. Depiction in the explanatory sense used by Kant or the reflective sense used by the early Wittgenstein is not the modality that is relevant here. Rather we must turn to the concept of construction, as in assembling a systematic picture out of what is otherwise unsystematic. Like the painter who forms a painting by applying his or her talents to pigments on a brush upon the canvas, so we, or rather the system within which we live and operate, as formed by the language and its attendant forms of life (as the later Wittgenstein often put it), applies the pigments to a canvas to turn disparate impinging sensory inputs into something recognizable and describable, with connections to other things and so comprehensible to ourselves. Language enables concept production in creatures like us. It’s the tool which allows for organizing and connecting disparate phenomena, the inputs of our senses, into a comprehensible world. We must look not to intuited forms or categories qua concepts but to the mechanisms of, and the activities of using those mechanisms, that is to language for the capacities needed to explain our ability to live in a world that extends beyond this very moment and place in which we happen to stand. To have a concept is to be able to formulate words that say something about something. Concepts are not the source of or answer to the question of how we form our world and our knowledge of it but are that world and that knowledge. And they are enabled not by some unknown features of human brains but by whatever features in our brains allow us to learn and use language.

Concepts can best be understood as the forms that enable us to know things, which is to say to know about things and language is the essential mechanism for making concepts happen. What we know is only known through the relations to other known things, relations within which whatever is known must stand. To have any thing at all, to have a world of things that makes us different from the other creatures of the world who lack the ability to frame their mental goings on in ways that permit communication with other creatures, there must be a means to organize their sensory inputs, to frame them. There must, that is, be language. Rather than supposing, as Kant did, that we represent the inchoate data of the world to ourselves through formal categories built into our brains, or, as the early Wittgenstein did, by presenting or showing themselves to us by our actions, here is the third possibility, made possible by Wittgenstein’s own later inputs: We apply a system of communicative signals, whether vocal, gestures or marks on paper, that provide a framework within which to relate the inputs we have thus turning them into objects of reference for ourselves, the language users.

Language, whether innate or developed by contact with the world (and I would argue for the latter, even if we grant that there must be an innate capacity to hold and use a language, thus implying a specified level of brain capacity—but not necessarily specific modalities of linguistic organization a la Chomsky), is all we actually need to explain the notions or concepts of space and time. We don’t have to do as Kant did and posit intuitive structures but, rather, recognize that language works as a system to enable its users to organize its inputs in ways that make better operation in the world possible. Language makes conceptualization possible, not vice versa.

This doesn't mean space and time don't exist until imposed on the world as such but only that nothing exists as distinct objects of reference, not even space or time nor anything else, unless there is a language within which to frame it. And language enables us to frame concepts of these latter things just as it enables framing of sensory inputs. Language is the means by which we bring a world into being, turning environments into worlds because, through it, we are empowered to think beyond the here and now and to conceive of the thises and the thats. Language gives us the tools to visualize our world as extending beyond our immediate surroundings. Because we have language, we can have a world rather than just this present moment in this immediate place. And we have language because we have brains capable of retaining information, previously encountered, and of organizing it in a way that enables new incoming sensory impingements to fit within what has already been received, organized and retained.

Language makes it possible to frame a world out of disparate, inchoate sensations by constructing a world using concepts. We don't represent one thing that is there to ourselves in some unverifiable or mysterious process of representation or picture-taking logically enabled. Rather we create what's there out of an otherwise inchoate flow of inputs through the application of our concept forming capacities which are enabled by language. So a better way of explaining the idea of having knowledge and how we have it would be to reject the notion that our knowledge is just about our representations to ourselves, or that, at least in some difficult-to-explain sense, it is something shown a la the early Wittgenstein, shown yet not said because we lack any ability to speak of it at all. Better, we must look, instead, to language itself, to the deployment of this capacity possessed by creatures like ourselves, a capacity which makes it possible to live in a world of things and their relations at all. Kant’s Copernican Revolution must be overthrown as must the pictures bequeathed to us by the Tractarian Wittgenstein. The answer is not transcendental but right here before our eyes in the way in which language enables creatures like ourselves to construct, and so live within, an ordered reality that encompasses what is observed and what isn’t.