Edward S. Casey: The World on Edge

The World on Edge Book Cover The World on Edge
Edward S. Casey
Indiana University Press
Paperback $42.00

Reviewed by: Lance Gracy (The University of Texas-San Antonio)


Following his book on the phenomenology of borders, in Up Against the Wall: Re-imagining the U.S.-Mexico Border (Austin: University of Texas Press, 2014), Edward Casey discusses relevant topics in, The World on Edge. Readers, in particular those readers sympathetic to peri-phenomenological methods to doing philosophy, are provided with refreshing insight into the world constituted by edges of metaphysical, ontological and phenomenological significance. In his book, Casey takes preoccupation with a description of the role of edges in the world. Indeed, what are edges? What is the significance of them? Casey’s pursues “the thesis that edges are constitutive not only of what we perceive, but also of what we think and of the places and events in which we are situated” (xiii). In this context, edges are not merely things worthy of storing, reflecting upon, or collecting; rather, they are “distinct presences” that are “essential to being a thing or thought” (xiii). According to Casey, edges play a dramatic role. As the drama of the world unfolds, edges “act” as a presence of being to “cut a dramatic figure” into not only our perception, but our thoughts as well (xiv). In the prelude to his book, Casey provides an image of an edge-of-presence, and by means of it we come to realize what Casey is after in his description of edges as “distinct presence.” In the given image, we see a mountain-edge cutting through light and darkness, along with a description of the edge, as if the edge itself had some poetic presence “to be light! And to thirst for the nightly!” (Nietzsche, 1999, 70-1). But Casey’s description of edges is more fundamental than poetics. He provides us with a description of edges as enantiodromia, Heraclitus’s word for the “sudden reversal into the opposite” (xvii). Accordingly, Casey gives us a description of enantiodromia as the “line of flight”, or in Deleuze and Guattari’s sense of the term, as a “quasi-linear structure that is inherently mobile rather than fixed” (xviii). Casey refers to this sort of edge as the “ultimate edge of our life”, which “bears up and bears out” what it edges (xv). At any rate, edges of this sort are related to dramatic experiences; that is to say, they compare and contrast world events, such as those of politics, or as Casey mentions specifically, the 2016 American presidential race, Tahrir square, and numerous other dramatic events—even our own death (xvii). As we see, reflect, perceive, and consider, we contemplate the “role of edges” as something of experienced dramatically “at every level” (xiii). What more is there to edges?


Casey is preoccupied with the question of “whether edges are something … or nothing—or perhaps next to nothing” (xvii). Assuming edges are something or next to nothing, what is the presence of an edge? How do we describe the presence of a world “on edge”? In relation to his primary thesis, Casey pursues “exact description of edges in four ways” (xviii). In part one, he examines “borders and boundaries”; he also examines “edges and limits, edges and surfaces, as well as distinctive sorts of edges that pertain to places and limits” (xix). In part two, he compares “naturally given and humanly constructed edges”, which are edges experienced in “wilderness” and “constructed environments” (ibid). In part three, Casey considers the edges of bodies “psychical rather than physical” (ibid). Taking the three descriptive ways into a phenomenological whole, Casey aims to describe edges pervading “our inner as well as our outer lives” and also “how they arise in the interaction between human beings and what surrounds them: in bodies and minds, things on the earth and sights in the sky” (ibid). Casey’s description of edges is a totalizing one; it takes into account the very nature of edges as that which is constitutive of our own phenomenological experience(s). In relation to Chalmers and others, Casey’s edges are constitutive presences, which are realized through description of them as a “pure phenomenal concept” and as essential to thoughts and things. According to Casey, this “pure phenomenal concept” is peri-phenomenological. His peri-phenomenology is a method of “exact description” of edges as a ‘being-around’ “ostensibly peripheral phenomena” (xix). Fair to say, Casey’s phenomenological approach to edges is one of “risk-taking.” Wondrously enough though, this risk-taking approach, or this peri-phenomenological approach, is precisely what one would experience if they were to “walk” the edge.

In chapter one, Casey introduces us to “borders and boundaries” concerning an exact description of edges. Casey’s description of edge as border and boundary amplifies the notion of Edith Stein’s “metaleptic communion” as the sense of unity and distinction between two concepts of being (even radically different concepts of being), such as that of ‘light’ and ‘darkness’ (Calcagno, 2009, 51). Invoking Husserl’s passage in Ideas I of “Descriptive and Exact Science”, Casey forms a synthetic idea about borders and borders through distinction of irregular and non-irregular (or eidetic) shapes (9). Here, the thought is that borders or boundaries (in relation to edges) constitute irregular shapes, and according to Husserl (and apparently Casey), these edges require a phenomenological description. In other words, because edges are not necessarily Euclidean, Casey calls for a peri-phenomenology of edges, as borders and boundaries, to describe the way in which we make sense of edges constituting some irregular shape or object. Walking us through a series of examples about the distinction between irregular (descriptive) and non-irregular (exact science) constitution, Casey states, “[B]oundaries, although nonlinear in their alliance with natural features, can be represented by linear means—where ‘represented’ means literally given representation, as if delegated to do so” (14). In this context, the explicit non-linearness of edges as borders and boundaries can be represented in terms of linearality. Thus, even irregular borders and boundaries can be represented in linear means—thus a sense of mathematical functionality to them—thus a sense of rationality to them. At any rate, “Borders and boundaries possess a special force or power” and the edges essential to their force or power have a variety of distinct purposes (16-7). One such power or force is the way edges as borders and boundaries “intertangle” themselves in our own thinking because of the variety of expressions involved with them (23-4). For example, an edge bordering two univocal expressions of light might “intertangle” us into a contemplative state. Casey clues us in to how we can rid ourselves of such intertanglement, by stating, “[I]n descriptive fact, the matter is more complex and more interesting. To admit this [intertanglement] is not to descend into descriptive taxonomic chaos; [to admit this intertanglement] is to discern an abiding order in the midst of complexity. Even as embodying several sorts of edge, a given edge will as a rule exemplify one primary or most salient form of edge” (24, emphasis mine). Casey’s clue here is a road into the dramatic role of “borders and boundaries” because it gives us a key for understanding how two distinct, yet univocally related beings, are related to each other. He provides the key thus: two distinct, yet univocally related, beings are related to each by the “most salient form of edge” that provides an “abiding order in the midst of complexity.” One’s concern about how two distinct beings related to each other is more importantly set in the essential thought of their distinct relation: i.e., the salient edge, or form, between them.

In continuing the first part of his exact description of edges, Casey identifies “distinctive sorts of edges that pertain to places and limits” (xix). He provides us with a depiction of ‘edge’ in relation to surface, thing and place (40). After a thorough analysis of ‘surface’, Casey offers a proposition as follows, “The edge is all but the shadow of the surface” (43). Moreover, neither edge nor surface are substances in themselves, but rather expressions of the substance. The edge is essential to the substance, and the surface, as Merleau-Ponty wrote, is “the surface of a depth, [of] a cross section upon a massive being” (44). As we understand Casey, a distinctive edge, when ensconced in the meaning of ‘limit’, is that which is in relation to a depth-of-being, some thing, or some substance. Casey further writes that this distinctive edge is not “wholly immaterial or insubstantial”, and that it becomes a surface by relation to the surface (44). Similar to Husserl’s notion of ‘phantom’, distinctive edges becoming surfaces are often “left out of consideration” in their “capacity to exercise” causality (Sokolowski, 1974, 95-6). Furthermore, in section nine of chapter one, Casey offers a distinction of edge and limit. He states, “Edges are primus inter pares, first among what is otherwise equal in the playing field constituted by limits and edges … they are neither fully present nor strictly absent” (55-6). On the other hand, limits “exist elsewhere than in the immediately surrounding world of places to which we belong as sentient creatures” (55). Edges, as distinct from limits, “join the company of certain other phenomena that exhibit a like ambiguity of presence: [e.g.,] the human body (as Merleau-Ponty insists in his discussion of the phantom limb phenomenon), and the human face (emphasized in Levinas’s ethics)” but in contrast “limits are forever beyond ‘the bounds of sense,’ whereas edges emerge from within these bounds and help to concretize and complicate what appears there, even as they also mark its very evanescence” (56). To summarize here: edges constitute beings, such as things or thoughts, by their presence, but they are not beings-in-themselves; and distinctive edges emerge from limits, and can be spoken of thus: as distinctive edges that help concretize and complicate beings (or substances). So although edges are themselves not concrete, by relation to concrete beings they can help concretize beings (or substances).

Continuing Casey’s “exact description”, we come to part two, in which he provides an analysis of “naturally given and humanly constructed edges”, which are edges experienced in “wilderness” and “constructed environments” (xix). Casey begins here with what he considers to be “intermediate edges” (184). Casey identifies intermediate edges as edges that are mixed in with the wild and “the cultivated and artifactual,” and are furthermore expressed through what Foucault called heterotopias; i.e., “other places” (185-6). Intermediate edges have a certain compresence within both inclusive environments (e.g., those of Carthusian monks) and exclusive environments (e.g., those of dog-parks) (187). Casey discusses the naturally-free and flowing structure or environmental identity of intermediate edges as settings which grant humans and animals a certain capacity to walk and move unrestricted, wherein is experienced a “balance of spirit and humility” (187-88). One of the grand settings Casey uses to exemplify a setting constituted by intermediate edges is Central Park. He describes Central Park as “a vast heterogeneous multiplicity whose constituent elements exist at many scales: human, more-than-human, other-than-human” as well as an environment that “would count as ‘a plane of consistency’,” which is what Deleuze and Guattari’s termed “a region whose considerable diversity is coherent despite all the differences in kind, level, and number” (190). Edges constituting spaces or settings like Central Park invite us to have “bold imagination,” or what the Greeks called “greatness of soul” (megalopsychia) (190). They also invite us to new life, vita nuova (191). In what could be a mighty recompense for the inactive days of post-industrial British poetic imagination, Casey actively describes the intelligence of environments constructed by both Mother Nature and human ingenuity. The intelligence is the edginess of the construct: Is this not itself an ‘edgy-idea’ essential to Dasein?

Neighborhoods are also examples of what Casey has in mind about a description of “naturally given and humanly constructed edges” (xix). Neighborhoods give us a sense of community, especially if we understand how neighborhoods are places and/or communities constituted by edges. In reference to what Casey writes, neighborhoods are constituted by edged-places, which, according to Husserl, are each a “near-sphere”; or according to Heidegger, each is a “nearness” (195). On page 196, Casey gives us an image of a neighborhood as some kind of neural highway having various functions—various edged-places that are constitutive of an edged-boundary, which is, “the neighborhood” itself. Casey lists “meeting places”, “gateways”, and areas of “restricted access” as examples of these edged-places (196). According to Casey, the neighborhood is where the magic happens; it is essential to beings; beings get their thoughts and feeling about other beings from it (198-99). As such, we return to Casey’s notion of edges: they are essential to a thing or thought—in particular, the thing or thought of “neighborhood.” Casey concludes his discussion of intermediate edges, or edges naturally given as well as humanly constructed, by stating, “Each edge is transitional, none is ultimate. But taken together, all such edges constitute a city as anything but static—as an ever-evolving interplay of edges. In cities, the edge is where the action is … Every city is first and last—and at many points in between—an edge city” (204). We could do well to be denizens of such a city: a city “on edge.”

Casey’s penultimate part of his book, part three, “Edges of Body and Psyche, Earth and Sky” explores a whole phenomenology of “the world on edge.” It might well be described as a phenomenology of being as a bodily-boundary that lives within the bodily or non-bodily boundaries of the kosmos. He states, “My body is an earth body, and the earth is inhabited by living bodies, not only mine and not only human bodies but those of all other living beings as well” (298). One question that arouses much curiosity, which is really at the center of the philosophical task of his book, is, as Casey states, “whether there are specifically psychical edges—edges of states of mind, of moods, of feelings, of thoughts. Do they really exist?” (236). Casey provides an altogether practical case for the existence of psychical edges. He states as follows, “However tempting it is to regard exemplary cases of having an edge as physical, this does not preclude the possibility of genuinely psychical edges—that is, edges that belong to soul … in their own right. And more than just the possibility! Psychical edges are altogether actual insofar as they are feltfelt by us directly” (237). Suffice it to say that Casey is not alone in his general argument for psychical edges. We needn’t look further than Cartesian dualism or the Meinongian idea of mental content having qualia to realize that “psychical edges” have traction in the traditional philosophical canon. It is at the very least an entertaining notion that edges are not merely physical and purely literal, but also psychical and non-literal. And Casey goes further. He gives a two-fold distinction about psychical edges: (1) outer psychical edges and (2) inner psychical edges (240-41). Casey provides an explanation of the language we can use to discuss these aspects of psychical edges (e.g., language within the concept of “falling apart” during mental breakdowns, pp. 242-46). Notwithstanding, Casey tells us, that, “The self clearly has to have some minimal unity to be considered as split from itself” (257). From this idea we return to Edith Stein’s “metaleptic communion”: although edges are inside and outside, there is at the very least a minimal sense of unity between two aspects of ‘edge’. This brings us to one possible purpose of Casey’s description of edges in his penultimate part of the book: to reveal to us the grandeur of edges as that which constitute our life inside and outside; our life within and without. There is something worth critiquing about Casey’s analysis. Casey’s suggests that there is a need to distinguish the unitary from formal unity (260). He provides a few reasons as to why he thinks there is a need to distinguish the two: one reason is that formal unity is “fixed and static in character” and another reason is that, “Unlike formal unities, the psychically unitary cannot be quantified” (261). There are a few questions we can ask about this seemingly strange need to distinguish the unitary from formal unity. As to the first question, is formal unity “fixed and static in character” necessarily? It would seem formal unity is not “fixed and static in character” necessarily. As to the second question, why can’t the “psychically unitary” be quantified? It would seem the “psychically unitary” can be quantified somehow. We can imagine Casey has a response to these questions in his inner-psychical edge.

In the latter end of his penultimate section of The World on Edge, Casey provides us with a description of edges in relation to the earth and the kosmos. These sorts of edges are multitudinous: edges near and far from us; edges that lead into the underworld; found edges and edges of horizon and landscape; edges under our feet and edges above our heads (i.e., “comparative luminescence”); edges of the earth and the edge of the earth (278-284). In distinguishing between “edges of” and “the edge of” the earth, or what we can term particular-universals and the universal, Casey states as follows,

[S]everal of [the “edges of the earth”] we see directly, as determinate features of our environment. They are  already there, awaiting our discovery and perception and measurement. Unlike the horizon or the ground, they are always multiple, belonging to this protuberance here or that rill over there. Whether they are  sought out or not, they come forward into our experience as configuring the surface of the earth. By  contrast, the edge of the earth is fugitive and recessive. It is neither a thing nor an event; it is fundamental  yet intermittently experienced, sometimes confronting us but just as often eluding us…” (281).

And interestingly, “the edge of the earth” can be experienced as something quite elusive. It is, as Casey tells us, “a situation of elemental obscurum per obscurius, being made ‘obscure by the more obscure’;” yet, ironically, “edges of the earth” can be, according to Casey, “edges of unclearly presented entities [that] tend … to be unclear” (287). Do we wonder about the outermost edge? Are we like Heraclitus looking up into the Heavens at the cost of practical awareness? As we wonder, do we come up with an answer about this outermost edge? Casey gives us an interesting conundrum to try and solve our wondering of the outermost edge. Turning to the medieval conundrum of the javelin thrower, he asks, “Into what does he throw his spear, if he is himself situated on the outer-most edge of the known universe?” (288). Referencing Kant, Casey provides us with this sort of answer to the conundrum: “[T]hought without content is empty, and speculative thinking on its own ends in impasse” (289). In other words, the outer-most edge is not an empty thought, but speculative thinking only will only burden us more. So try, if you wish, to answer the conundrum, but know when to stop!

At any rate, Casey reaches his conclusive edge: the human being’s paradigmatic edge, their ultimate edge: Death, “beyond which there is no other” (343). Casey’s understanding of death constitutes paradoxical meanings about the psychical and psychical, such as his term “living death” (i.e., civic and social death), and “biological death” (344-45). In addition, Casey’s “ultimate edge of death” is one way of blending the psychical and psychical into one coherent meaning: “the final edge of life!” This edge is a border and boundary of the human condition, and it “cannot be reversed or crossed back over” (344). In this context, edges surely “cut a dramatic figure” into human existence, for edges “cut-around” the meaning of the body as it approaches its end, its “ultimate edge”, its autopsy (so to speak). Casey reveals to us that even though there are edges of thoughtful consideration, or those of pure speculation conducive to our curiosity, how much more curious and contemplative should we be about the ultimate “razor-edge” of our life: our very death! An old proverbial wisdom speaks keenly here: Indeed, the wise one thinks much of the Heavens, but they also they think much of death!

In summary, Casey calls his way of proceeding in his book “peri-phenomenology” (300). As Casey tells us, edges are precarious. Given that edges are associated with “risk”, peri-phenomenology is an apt way to go about edges carefully because peri-phenomenology does just that: it moves about contextual surroundings, which is, in certain cases, context-sensitive edges. What’s more: Casey appears to do exactly what he intended to do with his thesis through his peri-phenomenological approach: an “exact description” of edges. Peri-phenomenology is indeed the force from which Casey’s work appears outstanding. His thorough and rigorous exact description releases some precious nuggets of philosophical wisdom—wisdom beckoning to us take heed of the progressive revelations of our day. Surely, Casey’s book is a worthy testament to the burdensome undertaking of “edge-walking” amidst present-day global issues—in particular, the edge-walking amidst the pitfalls of political, societal, and even academic, issues. Casey’s understanding of “edge-walking” in this context is a precise sort of wisdom. He states as follows,

“What I have called the edge-world is not only a world composed of intricate patterns and permutations of edges; it is also a world that is itself on edge. As a consequence, each of us is pitched on a thousand edges—edges on which we shake and tremble even as we pretend to go about our lives undisturbed. Our equanimity is only skin-deep; underneath it the abysses gape open, not just at the far edge of the known world or at the base of a precipice. We are denizens of a world on edge, and we are ourselves creatures of exposed edges. This is not just a matter of being accident-prone or vulnerable as individuals. We carry risk to others, endangering their lives as well as our own. Whole populations of human beings have been decimated by their fellow humans. Many animal and bird species have been rendered extinct because of human actions in the Anthropocene. Now we are on the verge of making ourselves extinct if humanly induced climate change takes its full vengeance. There is no way to exist on earth, no alternative path, other than to follow the edges that guide us even as they expose us to risk at every turn. We must take such exposure into account, learning how to identify those edges that are likely to lead us astray: each of us exists on a perpetual visual cliff. Some edges bring us to an unwelcome fate for which we are not adequately prepared: on these I have focused in this epilogue. Instead of trying to forget them or merely regret them, we must think on them, reflecting on what they portend. Becoming wary of certain edges, we can come to trust other edges that will configure our life-worlds in ways that are both more constructive and more creative. These more auspicious edges point the way for us, incisively even if not infallibly. Thoughtfully traversed, they are able to liberate us, indicating directions with the potential to save us from our own destructive and self-destructive ventures” (351).

Able to liberate us, and able to give great meaning to life as well! Certainly, edges are essential to human beings, and they play a dramatic role. Of course, we can offer a critique of Casey’s work in the form of stating that there ought to be an answer as to why there is a “need to distinguish” formal unity from the unitary. Casey’s line of reasoning doesn’t seem to evince in us a sufficient reason as to why there is a need for such a distinction (as noted earlier in this review), but this critique doesn’t bear on the high performance and outstanding nature of Casey’s work. The critique is rather some pleasing outcome of Casey’s peri-phenomenological approach; and, in addition, it points out an interesting topic of discussion (e.g., formal unity vs. the unitary). In closing, I conclude by stating that Casey provides us with a refreshing and reinvigorating analysis of the world, The World on Edge. His book is a masterful ode to phenomenology, for it encourages phenomenologists to benefit from a seemingly neglected approach to phenomenology: peri-phenomenology. The methodology of it is a beneficial one, as it is capable of navigating numerous closely-related topics in “exact description.” With no serious doubt, Edward Casey has achieved something remarkable with his book, The World on Edge. Philosophers are hereby encouraged to read it, lest they lose their confidence to “walk the edge”!


Nietzsche, Friederich. 1999. Thus Spake Zarathustra. New York: Dover Publications: 70-1. Print. (Original published, 1883).

Sokolowski, Robert. 1974. Husserlian Meditations. US: Northwestern University Press: 95-6.  Print.

Calcagno, Antonio (2009). The Philosophy of Edith Stein. Pennsylvania: Duquesne University Press: 51. Print.

Edward S. Casey: The World on Edge, Indiana University Press, 2017

The World on Edge Book Cover The World on Edge
Studies in Continental Thought
Edward S. Casey
Indiana University Press
Paperback $42.00