This post was originally published by the Institute of Art and Ideas and is republished here with permission as part of the Blog of APA’s partnership with the Institute.
David Hume and Immanuel Kant were almost contemporaries, but they reached radically different conclusions on the nature of reality and our ability, or lack thereof, to access it. Hume cast doubt on humans’ ability to ever really know the reasons or fundamental truths behind our experience. Kant, in response, proposed a revolution in our understanding of our relationships to ourselves and to the outside world, and in doing so offered a way to maintain knowledge of the physical world.
What is the relationship between our understanding of the physical world, and the physical world itself? Does our ability to reason somehow give us direct access to external objects? Or is our understanding particular to our psychological makeup? And, if the latter: how can we know that the ideas we form about the physical world bear any resemblance to the “real thing” as it is “out there”?
In fact, how is it possible that thoughts and things can resemble one another at all, given that we take them to be so fundamentally different? The philosophy of Immanuel Kant defends a useful approach to the world “out there” that departs from and then overcomes the empiricism of his contemporary David Hume to argue that by studying our very way of knowing, we better understand what there is to know.
For Hume, as for his rationalist and empiricist contemporaries writing in the early eighteenth century, the question of the relationship between objects and our understanding of them was closely bound up with the question of origin: where do the ideas that we employ when we think about objects come from? Most famously, Hume asked this question with respect to causality.
The concept of causality (that some event, x, is directly responsible for some other event, y) might seem so integral to our experience of the world that it is difficult to imagine a world without it. But when we try to point to something in experience that makes a series of events causal, this something remains elusive. We can’t see the causal relationship itself, but only two events: one that we take to be the cause and the other that we take to be the effect.
It’s true that we could point to the fact that certain events are usually or always followed by certain other events. But causality is something more than this: there is a sense that when one event happens, the other is in some way inevitable, and that the first event is the reason for the second. So where does this concept come from? Hume proposes that it is a product of psychological processes: If we experience event A followed by event B enough times, we will begin to expect event B whenever we encounter event A. It is this feeling of expectation that forms the basis of the concept of causality.
But this presents us with a problem. If the concept of causality were something that we could arrive at through logic alone, then we could make some sense of its relationship to real objects in the physical world: logic arguably provides us with some direct access to objects because it establishes what is and isn’t possible. Alternatively, if we believed that causality could be directly perceived in objects, then it is clear to see how the concept might resemble the world as it really is. But if the origin of a concept is psychological, we have no way of knowing whether it bears any resemblance to the world as it really is. In fact, more than that, it is difficult to imagine how it could.
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In the Critique of Pure Reason, Kant borrows some terminology from law to help him to distinguish between two kinds of questions. A quaestio facti (“question of fact”) is the kind of question that in law might be answered by a jury; it is about gathering evidence to draw conclusions about the world. The more evidence we gather, the more confident we can be in our conclusions. A quaestio juris (“question of law”), on the other hand, is the kind of question that’s answered by a judge. Its subject matter is much less tangible: supposing the facts alleged are true, what laws apply? Importantly, the way of answering these two questions is fundamentally different. No amount of examining the facts of the case can, on its own, tell the judge which laws apply. Instead, they must attempt to interpret the law to establish under what circumstances it might apply.
So why draw our attention to this distinction? Kant thinks that it provides a useful framework for thinking about the kind of questions that Hume poses: questions that relate to our knowledge of the external world. There are a set of questions, analogous to the quaestio facti, that have to do with matters of fact in the physical world. These are the kinds of questions that can be answered by science.
Suppose, for example, I want to know whether cats in the wild tend to live alone or in small groups. I can find the answer to this question by observing some cats. I can never be absolutely certain in my conclusions (even if I can somehow observe all the cats in the world, tomorrow things might change), but the more cats I observe, the more confident I can be. Like a jury in a criminal trial, then, any skepticism about matters of fact is a matter of degree. Hume’s account of how we come to apply the concept of causality in any given instance answers a kind of quaestio facti.
But there is a separate set of questions, analogous to the quaestio juris. These questions have to do with the legitimacy of certain concepts (our “right” to apply them to objects), especially where there is nothing obvious that we can point to in experience to distinguish cases where the concept applies and cases where it doesn’t. By way of example, Kant points to the concept of “fate”. The idea that there is some greater plan behind events in the world is not uncommon, yet there doesn’t seem to be any perceptible difference between a world that’s governed by fate and a world that’s not. We might ask “quid juris?” about this concept—“what right” do we have to use it?
If we fail to satisfy the quaestio juris, the skepticism that results is very different from the skepticism that results from a failure to satisfy the quaestio facti. It’s not just that we can’t be confident in our use of a concept: we have no justification for using the concept at all. Hume’s concerns about whether the concept of causality can apply to objects in the physical world, given its apparent psychological origins, transforms the nature of his investigation from a quaestio facti into a kind of quaestio juris.
So how might we address this quaestio juris? Just as the judge must employ a distinct methodology from that of the jury in order to answer her quaestio juris, Kant argues that we must employ a distinct methodology to answer ours: the transcendental argument.
In order to make a transcendental argument, we accept the skeptic’s conclusion—we can’t know anything “as it is in itself”—but with an important difference. The skeptic starts from the premise of a division of inner self and outer, objective, world. Since we don’t have immediate access to the objective world, but only to our (re)constructions of it, we have no way of knowing whether and how the two match up.
But Kant points out that the division is also not an “in itself” or something that we have immediate access to: it, too, must be constructed. And if we know the principles through which it is constructed, then we can know something about the outer world. It’s true that the object that we know doesn’t exist entirely independently of this framework. But neither is it a product of the inner self as the skeptic imagines, since the inner self comes about only through this process of division. A successful transcendental argument establishes that the concept in question applies to objects in the physical world because it’s somehow intrinsic to this framework of knower and objective world to be known.
Kant argues that the concept of causality is necessary to distinguish a world that changes—a world extended in time. Our perceptions are in constant flux, yet we only attribute some of this to changes in the object we are perceiving. The rest, we attribute to a change in ourselves, or our perspective. On what basis do we make this distinction? Kant argues that we take change to be objective—something happening in the object we’re observing—when we think that there’s something necessary about the order of our experiences. As a tree grows, for example, my perceptions of it are necessarily ordered from small to large. But if a tree appears smaller as I move away from it, I don’t think that the tree itself has changed: the tree could just as easily increase in size again once I move closer to it. In other words, it is in some sense the irreversibility of experiences that determines a real change in the physical world. Kant thinks that this irreversibility is what underpins our concept of causality.
In a strange way, then, we come full circle: by taking the skeptic’s premise to its logical conclusion, Kant arrives at a radical kind of realism about the physical world: existence or objective reality is already necessarily governed by the concepts and principles that make the distinction between inner and outer sense—subjective experience and an objective world—possible at all. If it were not, then we would not be in a position to encounter it. In fact, Kant thinks that we would not be in a position to encounter ourselves.
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So why should we care about all of this? Whether or not we accept Kant’s position on causality, the distinction he draws between quaestio juris and quaestio facti is helpful in avoiding all kinds of intellectual knots. For the vast majority of questions we have about the external world, we can get by without ever thinking about the quaestio juris. The world already does exist, and our job is usually to try to make sense of it as it is.
But the enormous success of the scientific method can make it tempting to treat every problem as though it were a quaestio facti—to expect, in other words, that science should be able to provide an exhaustive explanation of reality, including the framework of science itself. The result of this can be skepticism: when it becomes clear that science can’t explain how mind and world could coincide, it can be tempting to conclude that they don’t, or at least that there is no way that we can know that they do. Kant’s attempt to respond to the quaestio juris shows us at least the possibility of an explanatory power external to, yet consistent with, science.
There are also implications for what it means to have, or to be, a mind. The “hard problem of consciousness” arises in part because we take the distinction between subjectivity and objectivity, mind and world, to be primary, and then attempt to explain one in terms of the other. The Kantian position recognizes the distinction as emergent and so allows for alternative conceptions of the relationship. What Kant offers us is not just a response to skepticism, but a profound reorientation. Instead of seeing mind and world as separate realms in need of a bridge, conceptual understanding is itself the process through which reality becomes articulated into both self and world.
Emily Fitton
Emily Fitton is a philosopher based in Essex, UK. She wrote her PhD on Kant and German Idealism and has published on causal skepticism and ethics in end-of-life care.
