Lives and their trajectories are an important topic. To begin with, each of us has one. This is possibly the greatest commonality that exists among people. Not only, moreover, does each of us have one, but the one each of us has—regardless of how socially structured or constituted it might be—is inescapably one’s own. Awareness of this situation can lend bitter poignancy to what someone does, experiences, and suffers—all this acting, undergoing, and suffering, it’s his, hers, or theirs and no one else’s, even if some of it is shared. This bite is well known to anyone conversant with existentialist literature.

Not surprisingly, accordingly, life and its trajectories have been deeply plumbed, by poets, novelists, philosophers, theologians, gurus, journalists, therapists of various stripes, an occasional statesperson, and others. Words of sobering, somber significance capture important aspects. In English, words like “fate,” “destiny,” “potential,” “achievement,” “dignity,” “choice,” “free will,” and “necessity” pick out notable features or possibilities of life that command or portend some portion of hope or despair, splendor or destitution. Life not just joins but means a lot to us humans.

Lives and their trajectories are also important for the social disciplines in toto. Regardless of what one thinks social life is ontologically, accounts of sociality must take account of, and at some point encompass, individual lives. Even if lives are not the objects, or even the chief constituents of the objects, that these disciplines study, these objects would have no substance, duration, or even existence absent human lives. The relationship between lives and social entities is one of the principal theoretical issues faced in these disciplines.

The current essay will not directly address this relationship. Instead, my discussion will focus on life, its trajectories, and the relationship between life trajectories and social practices. My aim is to help illuminate the phenomena that life course research in general, and the Doing Transitions approach in particular, study. More specifically, I will link a phenomenological account of human life and its trajectories to a practice theoretical approach to the social contexts in which lives proceed (on this combination, see Schatzki, 2017). In doing so, the essay will help show what it is for lives, and their phases and transitions, to be “constituted by practices.”

What Is a Life?

The word “life” points toward a tangled conceptual field. Life used to be a, if not the, premier concept in biology: for decades, biology was defined as the study of living organisms. In this discipline, life entails such properties as reproduction, metabolism, growth, and self-organization. Life, however, is too important to be left to the biologists. Although the concept of life must retain its biological dimensions, it must also offer something to the flights of poetry and philosophy.

Distinguishing the notion of “a life” from the notion of life full stop points in a salutary direction. A life is something that stretches from beginning to death (cf. the ancient Greek zoe, which designates something opposed to death). The notion applies to creatures more diverse than humans, thus ensuring some continuity with the biological phenomenon. But the notion assumes special meaning in relation to humans, or better, people, in part because we seem to bear an unusually complex relationship to death. Human lives are biological and, like lives generally, stretch from beginning to death. But a human life is a refined version of something that is biological and shared with members of other species. The ancient Greek bios, which is a human affair embracing, among other things, biography and way of being, captures the idea.

I begin with a feature of a life that emphasizes commonality with other species. A life embraces a continuing series of sensory—or just detectional—events in, and movements carried out by, a functioning organism. This characterization brackets the properties typically treated as definitive of biological life. It does not apply, for instance, to an utterly comatose person, who is alive biologically. It instead picks out something stretching from beginning to death that is common to many living beings.

This sensory-movement continuum assumes a richer form with a more complex trajectory in the vast majority of human lives. There, it becomes a life of self-conscious action, where to be self-conscious is to be aware that one is alive. Such a life might be unique to humans; it might also be shared with higher mammals such as dolphins, bonobos, and elephants (not to mention aliens). The more complex sort of trajectory it possesses in comparison to a basic life of continual sensory mobility lies less in a person’s directed passage through a cognized world—a sort of existence shared with other organisms—than in, among other things, a life always embracing a significative arc stretching from past to future (see section “The Trajectories of a Life”). When a person understands that she is alive, the questions that make up the title of Gauguin’s famous 1897–1898 painting—e.g., Where do we Come From? Where are we Going?—become and remain meaningful, at least until death or the loss of one’s faculties. Life thus understood is familiar to all of us. It poses the types of issues, and brooks the sort of considerations, that the social disciplines raise about life trajectories. These issues and considerations presume that lives are self-conscious.

A life as we live it embraces a procession of activities performed and “psychological” conditions expressed by an active body (see Schatzki, 1996). The “psychological” conditions involved include states of consciousness, emotions, and conative as well as cognitive conditions (such as self-consciousness). Incidentally, to say that psychological conditions are “expressed” by the active body is to say that psychological conditions are present and encounterable in public space by way of bodily activity; other people can also interpretively infer the existence of such conditions. An important feature of the activities and conditions that make up a life is that they belong to a specific person, namely, the person living. They belong to this person because it has been a feature of human practices for many millennia now to attribute the performance of actions and the possession or undergoing of mental and cognitive conditions to the person whose body expresses them. This makes the relationship of a person to her body central to a life. It also provides a first glimpse in this essay of the profound social constitution of lives.

Another feature of a life is that it incorporates the world. Important events are part of our lives. They are, among other things, incorporated into the narratives we tell about our pasts. I remember, for instance, when the Red Sox lost the 1976 baseball World Series; it is a notable reference point in my life. This incorporation of the world into a life can be accommodated by treating select, or in principle all, objects of a person’s activities or mental and conative/cognitive conditions as part of her life. Lives are open to the world in a second important way. Which “psychological” condition is expressed by any given piece of bodily activity, just like which action is performed through the performance of a particular bodily action (see below), often depends on the context in which it occurs. Crying, for instance, expresses joy or distress depending on, for example, whether it is preceded by a great victory or by a scathing insult. Relevant contexts include states of the world and past and future actions (see Schatzki, 1996). In this way, the identities of many components of a life depend on how things are in the world.

Finally, the actions and “psychological” conditions that make up a life overlap. Life is a mosaic of processes and conditions that differentially start, connect, and cease.

The following discussion highlights actions and de-emphasizes “psychological” conditions. It does so because activity is what centrally gives a life its trajectories, in part because activity is processual in character and in part because many “psychological” conditions accompany activity. Biological development from beginning through youth and adulthood to old age and death also grounds trajectories. In emphasizing activity, I do not deny that passivity, or being, is an important dimension of a life. Many life conditions, including sensations, emotions, and beliefs, happen to or hold of people. Biological processes and developments likewise happen to them, as does the impingement of the world (including other people). Through it all, however, a person, even if she “withdraws,” forges ahead in action. Nor, moreover, do I deny that experience, or as Tim Ingold (2015, 126) puts it, “undergoing,” is important to life. Indeed, in the past I have often conceptualized activity as experiential activity to emphasize that activity transpires within the ken of experience. If the topic of this paper were life and not life trajectories greater attention would have to be paid to both being and experience.

In the following, consequently, a life will be treated as a procession—in Bernardi et al.’s, 2019 words, as an “individual behavioral process” composed—of overlapping activities that are constituted in bodily doings and sayings performed by a self-conscious living person and whose identities as particular activities depend on states of the world in the context of which they happen.

This phenomenological conception of a life treats it as a process. This process includes bodily doings and the actions they constitute; it also incorporates and is partly defined by the world through which it proceeds. It is not, however, a process in the sense of (1) a Bergsonian (1999) dureé (an ongoing unfolding advancing), (2) a pragmatist passage through or in relation to present experience, or (3) a mere series of events. For example, I do not, as is common, treat a life as a moving stream or as constant becoming (see, for example, Ingold, 2015, whose phenomenological accounts of wayfaring and navigating I affirm). Rather, life is a process in a Rescherian (1996) sense of a continuous integrated nexus of events, in this case, activities (and “psychological” conditions). What integrates the events composing a life are the body that expresses them and the person to whom they are ascribed. Interesting life possibilities arise when the one-to-one relationship of body to person shifts, as when multiple people (personalities) occupy the same body.

The Trajectories of a Life

Sociological life course research construes the life course as the progression of events—above all, activities—that make up a life over its entire history (cf. Featherman, 1981). This total series is composed of multiple trajectories, each embracing the events and transitions that make up the progress of that life in specific life domains, or institutional spheres, such as work, family, and education (cf. Elder, 1985). In this essay, by contrast, the trajectories of a life are construed as certain key dimensions of a life qua continually forward-unfolding entity. The plurality of trajectories reflects, not the diversity of life domains, but the fact that the character of life as continually unfolding exhibits several key dimensions. A trajectory, as the life course literature construes it, in my sense is, or corresponds to, a series of discontinuous episodes in a life. These episodes are socially constituted in ways that will be touched on below.

Three sorts of trajectories will be distinguished in this essay.

Space-Time Paths

A life trajectory is, first, the space-time path of a life, that is, the path through space and time that it traces as it proceeds. In this context, space means three-dimensional space, and the specific spaces involved are material ones, that is, occupied or defined by collections of material objects. Lives trace a path through these material spaces (in a sense explained below). Time, furthermore, means before-and-after time: the ordering of events and processes into successions by virtue of before and after relations between them. Lives take up their places in such successions, the various bodily doings and activities (as well as psychological conditions) that compose them occurring before or after other events and processes in the world. The same holds of entire lives, which likewise transpire before and after other events and processes.

Strictly speaking, the only thing that can trace a path through material space is a material entity. Lives, however, are not material entities. Nor are activities. It is the body at and through which a life unfolds that is a material entity. However, activities (and psychological conditions) are always intimately connected to material entities. In particular, as indicated, they are constituted by bodily movements. It also seems eminently plausible that they are connected, in various ways, to the neural, endocrinal, and muscular-skeletal bodily systems among others. And they clearly presuppose particular bodily processes. Given this rich relationship, it makes sense to define the spatial-temporal paths of lives as the spatial-temporal paths traced by actors’ bodies as they move about in the world.

Performances of action, too, are located in material space and positioned in before-and-after time. This is because any action a person performs is performed through the carrying out of one or more bodily doings (voluntary bodily movements), which in the situation of performance constitute the performance of the action in question. For instance, one can greet a friend from afar by waving one’s hand back and forth because, in the context of encountering friends, such a bodily doing amounts to a greeting. All performances of action, including mental actions such as thinking, involve performances of bodily doings, in the case of thinking, such doings as furrowing one’s brow, pacing back and forth, drawing on a chalkboard, and gesticulating in the air. (Omissions, moreover, involve omissions of bodily doings that constitute actions that are expected, appropriate, or sensible in particular circumstances.) It follows that the performance of an action is located at all the locations in material space where the bodily doings that compose it are located. This location is usually a point or a curved or jagged line; a discontinuous line is also possible.

A person is always doing something, at least while they are awake. The movement, moreover, of that person’s body through space describes a continuous line: as Ingold (2015, 118) writes, to lead a life is to lay down a line. This lifeline is broken into overlapping segments that are where the person performs particular actions (it is also broken into longer episodes—or “durations”—that make up her trajectories through particular life domains). The path that her body takes through before-and-after time and material space thus defines the path taken by her bodily performances of actions (and bodily expressions of “psychological” conditions), which is at once the space-time path taken by her life.

Sequences of Action

A life trajectory is not just the space-time path traced via the movement and movements of a living person’s body. It is also the sequence of actions performed in a life, the sequence of actions performed by a living person. Unlike passage through space-time, this trajectory is irreversible (a fact that makes life transitions possible). This is because an action always occurs in a context that includes the actor’s earlier actions and that itself helps form the context in which her subsequent actions take place. As, consequently, her life progresses, the context in which it proceeds includes ever more actions and sequences of action that the person herself performed. Future actions can double back and help create situations that resemble situations in which earlier actions of hers were performed. But a life cannot literally repeat actions in reverse order since each further action—not to mention other events and processes—only makes the situations of subsequent actions increasingly unlike those of predecessors.

Trajectories as sequences boast a type of direction, namely, steering toward yet another activity, that is, toward the next activity performed. This phenomenon can be called “progression.” Life trajectories progress so long as they exist, and it is due to their progressive nature that they accumulate, or leave behind, ever longer successions of activities. This sort of directionality is inherent to an active being. Note that the first sort of trajectory, spatial-temporal passage, possesses a parallel type of direction: a perpetual moving forward in time.

Performances of actions are events. Accordingly, a succession of action performances is, ontologically, a sequence of events. Obviously diachronic in character, any such succession also has a synchronic structure, in which performances help compose broader activities that can be called “projects.” Looking for a job, for instance, is a project embracing multiple narrower actions: consulting web sites, talking to friends, designing a resumé, going to interviews, and so on. In turn, looking for a job can be part of a wider project, for instance, getting one’s life in order. The synchronic structure of a life trajectory as a sequence of actions is a stack (cf. Caliskan, 2020) of overlapping, progressively wider actions. While the upper reaches of the stack usually metamorphose slowly, its base layer comprises the more frequent and rapid bodily actions whose performance constitutes intentional actions. I mention this structure because it provides a medium for sociality. It thereby helps fill out the idea of “linked lives” (see Elder et al., 2003; Settersten, 2015; cf. Ingold’s, 2015 notion of “knotted” lives) that the Doing Transitions project draws on to mark the fact that transitions depend on other people. For example, talking to friends about job opportunities involves (1) performing actions that causally interlock with and are otherwise directed toward friends’ performances (i.e., interactions; more generally, chains of activity—see section “Life Trajectories and Chains of Action”); (2) the intersection and coordination of, as well as the presence of references to others’ lives in, the synchronic structures of the various players’ life trajectories; and (3) the practices within whose scope the causally interlocking actions are performed and the intersection, coordination, and mutual referring are established. As this suggests, sociality, and thus the social constitution of individual lives including their phases and transitions, depends on such phenomena as interactions with others, the intertwined stacked character of different people’s activities and life trajectories, and the common practices people carry on.

Closely connected to life trajectories as sequences of actions is the idea of life phases. A life trajectory, like most any process, can be broken into phases of many different sorts. These include numerous, possibly fleeting segments of lesser significance such as those that make up a typical start of the day: enjoying a caffein beverage, consuming food, personal hygiene, dressing, walking the dogs, and going to work. Likewise possible are fewer, usually longer stages of greater significance such as the durations that compose the trajectories of a person’s participation in particular life domains and the very long phases included in the once dominant tripartite model of the life-course (Kohli, 1985). Life trajectories can be broken into multiple series of phases because different conditions and discursive criteria can be marshalled to demarcate (and name) segments or stages of activity sequences. These criteria include those that define “normal” life courses, which discursively circulate among practices with institutional backing. Divisions of normal or normativized lives—or generations—into major phases (i.e., segments of social clocks; Neugarten & Datan, 1973), vary across “cultures”: the above examples pertain to lives in North Atlantic countries, though they share many elements with lives in other parts of the world.

Phases are sequential and linked by transitions. As suggested, many sorts of things exist between which people transition. Over the course of a day, for instance, a person proceeds from situation to situation, from one life domain to another, and from one physical station to another (see Hägerstrand, 1975), each switch a “transition.” Over time, many other transitions occur in significant aspects of particular lives or collections thereof, for instance, in the divvying up of work required to maintain a home, in jobs, in family situations, in friendships, and so on. There are also important, typically age-related status transitions of sorts that members of particular collectivities mark, for instance, in membership status (e.g., initiation, baptism), marital status, education achievement, retirement, puberty and majority, and so forth. Transitions of these sorts are flanked by important life phases, for example, childhood and adolescence, high school and university, minor and adult. At the base of all these phases and transitions lie the sequences of actions that compose the trajectories of lives day in, day out. These sequences provide the raw material for phases and transitions, which incorporate segments and stretches of the sequences. Incidentally, life trajectories are structured, not just by discourses and institutions, but also by, among other things, phases and transitions themselves. For, as a general matter, action sequences are shaped by the social practices they pass through (see section “Trajectories, Bundles of Practices, and Material Arrangements”), and social practices often explicitly mark, and what people do in them is sometimes organized by reference to, phases and transitions.

Pasts and Futures

A third sort of trajectory that characterizes most human lives is an omnipresent structuring arc from past to future (see Schatzki, 2010). A life not only inexorably proceeds to the next thing done. It also always heads somewhere, toward something to be realized. This heading toward concerns the future. It is captured in more familiar terms by the notions of purpose and end. Purposes and ends are the states of affair a person aims at, or comes toward, in acting. Whereas purposes are more immediate and often tied to particular intentional actions, ends are more distant and often require the performance of multiple actions. Practically all human activities display a multidimensional future of this sort. In typing on a keyboard, for instance, someone might be searching an online job site, which she pursues in order to check out hot leads about jobs, which is part of the project of looking for a job, which she seeks for the sake of bringing order to her life. Human action is practically always teleological (which does not imply that people are conscious of their ends as they act).

At the same time, life always comes from somewhere. A person reacts to or proceeds in the light of particular states of affair. These state of affairs are where she comes from in heading toward what she seeks to realize, that because of which it makes sense to her to do such and such in pursuit of this and that purpose and end.

Life always displays this structure of coming from-heading toward and, as a result, contains an arc from what one comes from to what one is headed toward. Significative trajectories of this sort omnipresently structure activity.

I should add that each activity in a life trajectory inflects that trajectory. What I mean is that, merely by occurring, each addition to the sequence of actions a person performs ipso facto alters what the trajectory of that person’s life has been. This alteration can be trivial and inconsequential as when the job seeker accesses a job advert through an online job site instead of clicking a link to the advert sent to her by a friend. Or it can be more momentous as when the person says to herself that she has had enough and abruptly abandons the search. (Of course, even assessing the site directly can have great consequences, as when job seeker picks up malware at the site’s portal that could have been avoided by following the link.) The next action in a sequence thereof can also send the sequence in a direction different from the direction the life had been taking before then. In fact, what a person does at any moment can in principle send the trajectory in a significantly new direction. This mutability derives from the character of activity as an event, according to which human activity is indeterminate until it happens (see Schatzki, 2010). As things are, life trajectories only infrequently head suddenly towards something different. Due to the action stack that structures a life trajectory, actions that pursue purposes different from those pursued by immediate predecessors often continue to pursue distal ends that the latter sought. A job seeker who suddenly stops searching the web in order to talk to a friend about the friend’s new employer is pursing the same more distant end as before—finding a job—even though the immediate purposes of searching online and consulting differ. A life trajectory is continually changing, not just in embracing additional activities and thereby both describing a longer space-time path and being composed of a different activity sequence, but also in incorporating different significative arcs.

All told, the trajectory of a life is made up of a phases-forming, transitions-embracing sequence of actions (and other life conditions) that describes a spatial-temporal path through the world and is omnipresently coming from somewhere in heading toward something.

Some theorists (e.g., Carr, 1986; MacIntyre, 1981) claim that one more sort of trajectory applies to a life. It is the courses of the stories or narratives that we tell about ourselves and our pasts. I do not include this sort of trajectory because, as I see things, narratives articulate how people should or do understand their lives. Narratives do not inherently structure either actions (see Schatzki, 2005) or lives; that is, actions and lives do not intrinsically have narratival structures. To be sure, the narratives people tell about their lives can affect how they act and inform the significative past-future arcs that structure their activities. This is especially true in societies with strong oral traditions. Such shaping also exemplifies the discursive molding of life trajectories, a topic of interest to the present book. But many phenomena affect people’s activities. The courses of people’s narratives are never their life trajectories but only help shape the latter.

Trajectories, Bundles of Practices, and Material Arrangements

According to theories of practices (see Schatzki, 2002), practices and constellations thereof make up the social contexts in which lives proceed and the phases and transitions of life occur: all transitions are experientially performed by people in constitutive social contexts composed of practices. As a result, practices bear responsibility for lives, phases, and transitions being social phenomena.

A practice is an open set of organized doings and sayings. Examples are cooking practices, wedding practices, day trading practices, teaching practices, university freshman orientation practices, and job searching practices. Practices are closely intertwined with—in some practice theories, they include—arrangements of material entities. Practices and material arrangements thereby form bundles; cooking in a kitchen or working in an office are examples. Particular practices can bundle with multiple arrangements; freshman orientation practices, for instance, can be pursued in different settings. Conversely, particular arrangements can link to multiple practices; consumer, job searching, entertainment, and information gathering practices, for instance, can be carried out at arrangements at home centered around a computer. Bundles, in turn, can connect—through relations pertaining to practices or arrangements—as constellations, which are just larger, more complicated bundles of practices and material arrangements. I use the expression “practice plenum” to denote the entirety of bundles and constellations.

Practices are composed of organized doings and sayings. This implies that any bundle of practices and material arrangements exhibits a dimension of activity that embraces the organized doings and sayings that compose its practices. This dimension is key to the relationship between life trajectories and bundles. For life trajectories, too, are made up of activities.

As a person goes through her day, she performs one action after another. Each of these activities is part of some practice and bundle, sometimes more than one practice and bundle. After getting up in the morning, for instance, a person might cook and then eat before turning to personal hygiene and getting dressed. While cooking and eating, the person carries out, that is, her activities are part of, cooking and eating practices. As a result, her life, for these stretches, coincides with these practices. If, the whole time, she also, in her head, plans a business meeting scheduled for later in the day, her life, for that stretch, also coincides with business practices. When, subsequently, she gets herself ready, her life coincides with personal hygiene practices, having left behind those of cooking and eating. And when she gets dressed, her activities are moments of dressing practices, having left behind those of cooking and eating and passed through those of personal hygiene. In this way, as a person goes through her day, her life episodically coincides with various practices and has passed through these practices once she moves on to further ones. (A similar analysis applies to the life trajectory of someone learning these practices since learning them involves either carrying on tentative, incomplete versions, for which room is made in the practices, or participating in distinct “learning” practices that are carried on as preludes to the practices themselves.) These coincidences can be considered phases, between which she transitions as her day develops.

Coinciding and passing through, like life phases and transitions, are temporal phenomena. They also involve space. To pass through a bundle, episodically coincide with its practices, is at once to proceed, and to trace a spatial path, amid the bundle’s material arrangement(s). To coincide with a practice, for example, the practice of job seeking, is to perform job seeking actions—navigating, talking, answering questions etc.—while proceeding, and moving amid, material arrangements set up or usable for job seeking.

A second type of space is also involved. Humans generally proceed through the world sensitive to arrays of places and paths distributed through their circumjacent environments. By “places” I mean places to perform specific actions (e.g., a place to sleep), whereas by “paths” I mean avenues for getting between places. Places and paths of these sorts are anchored in the material entities and arrangements thereof amid which people proceed. Which places and paths, moreover, are distributed through circumjacent environments is tied to people’s ends; a kitchen table, for example, can be a place to eat given the end of consuming a meal or a place to search for a job given the end of being employed. Which places and paths are anchored where is also tied to social norms that determine what is prescribed or allowed to be done at or in relation to particular material entities (e.g., it is a social norm that a bed is a place to sleep). As people pass through a bundle, they are sensitive to arrays of places and paths that are tied both to the ends permitted and prescribed in the bundle’s practices and to actions that are acceptable or prescribed to perform there at or toward the components of its material arrangements. Passing through a bundle thus entails that a segment of the sequence of actions that composes a life coincides with practices that are entwined with the material arrangements through which the trajectory cuts a spatial-temporal path and across which places and paths are distributed to which the course of that segment is sensitive. All of this, finally, might transpire in a particular encompassing place: a meaningful localized region through which people proceed related to it as a whole. This encompassing place could be one’s room, one’s home or neighborhood, a work institution, a community, a country etc.

Before and after a life trajectory passes through a bundle of practices it lies outside the bundle. Even though, moreover, a life trajectory, during any stretch of time, lies outside many bundles, it always also coincides with some bundle(s) or other. This implies that, even though the trajectory, like any trajectory, lies outside many bundles in the practice plenum, it never lies outside the plenum. Over the course of a day, month, or lifetime, a life trajectory passes through a multitude of bundles, sometimes repeatedly, sometimes doubling back, sometimes in a regular sequence, and sometimes in unique combinations or sequences. Trajectories can even, usually jointly, extend the practice plenum by adding to or annexing further stretches of the material world to its material arrangements or sending chosen material entities into new material environments (e.g., the Voyager satellites).

Coinciding with and passing through are not the only relations that life trajectories bear to bundles. Trajectories also proceed dependent on bundles and on the background of bundles. These are two modalities of a wider phenomenon, namely, the sensitivity of human activity to states of the world.

All sorts of elements of a life, including its trajectories, phases, and transitions, depend on bundles, both those the life involved passes through and ones it proceeds outside of. This dependence can take different forms. For instance, the normative organizations of practices shape how participants in them proceed; this is an important vehicle by which discursive or institutional norms shape trajectories and the durations they exhibit (whether trajectories are construed à la life course research or the present essay). Via memory, moreover, bundles and what goes on in them can affect subsequent moments and phases of the lives that coincide with and pass through them. Similarly, learning, which involves the acquisition of knowledge, know-how, tastes, virtues, and the like, occurs as and as a result of people carrying on certain practices. Like the ability to recall past perceptual experiences, what is learned accumulates (and modulates as well as dissipates) and can affect later moments of life trajectories. Memory and learning are key mediators through which practices and constellations thereof shape trajectories, phases, and transitions.

Life trajectories likewise proceed on the background of bundles. The background comprises everything, given which a person acts as he does. An important component of the background encompasses everything a person experiences, knows, or is familiar with that (1) helps determine what makes sense to him to do, including in reaction to something, or (2) makes him the sort of person who reacts as he did to that thing. A teacher who awards a student for repeated good work reacts to that student’s history of good work. In the background of this action lie items, experience of or familiarity with which makes him the sort of person who welcomes and is inclined to award good work, for example, having received similar treatment himself when younger, admonishments from administrators to profile good students, a teaching workshop that emphasized the benefits to all students of recognizing good work, and so on. An important subtype of this component of the background comprises practices. For people often perpetuate practices with which they are familiar—especially those that they have “lived into” (einleben in)— without giving much thought to what they are doing. The teacher, for instance, might have grown up in a school system in which rewarding excellence was a widespread practice and then unreflexively rewarded the student after realizing that she had long been doing good work.

More expansively, bundles, and the practices and material arrangements that compose them, lie in the background of many actions and thus in the background of a life’s trajectories, phases, and transitions. They contain matters, familiarity with or knowledge of which either helps shape what makes sense to people to do or makes people inclined to react in particular ways. Bundles also provide patterns of action, which people fall in line with. All these matters help fill out the situatedness of human activity.

In the introduction to the present volume, the editors explicate how a transition involves a bundle of practices. As explained, this means that any transition embraces segments of life trajectories in my sense that coincide with and move among the varied practices that make up the bundle involved. A transition, accordingly, embraces movement among practices. As I have explained, what moves between them are lives. A transition, as a result, involves one or more life trajectories in my sense passing through a variegated constellation of practices. Of course, it is not just this. As the editors argue, transitions also involve a variety of social processes that bear on life trajectories, above all, relations among individuals, institutional regulation, and discursive information. The bundle of practices that is involved in a transition thus embraces not only the practices that the transitioning life or lives coincide with but also those through which other actors, institutions, and discourses shape, regulate, and co-constitute these lives. Because of this, transitions can be described as “relational.” Still, the peregrinations of lives (through bundles) are fundamental: without individual lives, there are no transitions. Indeed, life trajectories other than that of a person undergoing a transition are part of the transition.

Life Trajectories and Chains of Action

The final topic for this essay is the apparent parallel, but in reality deep divergence, between life trajectories and chains of action. In a recent book (Schatzki, 2019), I argue that chains of activity are one of the two chief dynamos of social change, the other being material events and processes. Social change, I argue there, is the product of nexuses of such chains, events, and processes. The reason I presently address the divergence of life trajectories from activity chains is to locate lives and what the life courses literature calls “agency”—a person’s construction through activity of her own life course, e.g., Elder et al., 2003; Schoon & Lyons-Amos, 2017, Bernardi et al., 2019—in the causal order of society.

A chain of activity is a series of actions, each of which responds to the prior member in the chain or to a change in the world that that earlier member brought about. A conversation, for example, is a chain of actions that goes back and forth among the interlocuters; a supply chain, meanwhile, is a nexus of chains involving many people and material intermediaries. Chains of action are ubiquitous in society. Whenever an action responds to a previous action or to a state of the world for which a previous action is responsible, a chain is extended. People respond to others’ actions and their effects all the time (think of being with your family, in traffic, at work, playing a sport, or doing political work). They also sometimes respond to states of affairs without being aware of who is responsible for them or that others are responsible for them at all: they pick up litter, swerve to miss objects on the highway, make investment decisions on the basis of price swings, and undermine august traditions. In all these cases, people extend chains of action.

One way a life trajectory differs from a chain of actions is that a trajectory—as a key dimension of a life—embraces the actions of one person whereas a chain contains actions performed by different people. Chains in effect cross—pass through—trajectories, linking them. Conversely, trajectories contain actions that extend chains. It is the multiplicity of trajectories that makes it possible for chains to continue via different people’s actions.

Another difference between trajectories and chains lies in their relationships to causality. Chains of activity house causality. One type of causality involved is prior actions and states of affairs leading to subsequent actions, that is, subsequent actions reacting to them. (Discourses and institutions mold transactions, and thus phases and transitions, by shaping how people react to prior actions and states of affairs.) A second type of causality is activity directly effecting changes in the world. It follows that each link in a chain of activity is causal: chains of activity are lines of causality that snake through the practice plenum, passing through practices and crossing life trajectories. As lines of causality, such chains, as stated, are responsible for social changes, including changes in trajectories, phases, and transitions. Life trajectories do not house causal relations in this way. Activities that succeed one another as part of a life trajectory do not, for the most part, bear causal relations to one another (one can, of course, react to one’s own past actions). They are, instead, different performances by one person at different moments or periods of time. The relations between them are largely noncausal, for example, temporal succession, being parts of the same larger actions (action stacks) and being performed by the same person. It follows that lives and their trajectories are not, generally speaking, causally responsible for the state of social affairs, including lives and their trajectories: they are instead crossing points of the causal strings responsible for these matters.

One final point. Activity chains are composed of activities, among other things. Life trajectories, too, are composed of activities, among other things. And practices, of course, are likewise composed of activities. In fact, one and the same activity can in principle be part of an action chain, an element of a life trajectory, and a component of a practice. One and the same activity is all three simultaneously whenever someone extends a chain in doing something that continues a given practice. This is not an infrequent event. Quite the contrary: it is the normal state of things.

This centrality of activity to chains, trajectories, and practices makes concrete how transitions are done: both the practices as part of which and the life trajectories through which transitions occur, like the chains of action that bear on these practices and trajectories, are composed centrally by actions.


Life trajectories are central to understanding a variety of human and social phenomena. They supply the actions that help constitute social states of affairs, including life phases and transitions, while themselves being molded by these affairs. They form a particular interest of biographers, historians, and poets. Contrary to the tenets of individualism, however, they are responsible for few social changes. Instead, causal determination in the form of chains of activity flows through lives en route to leaving changed social phenomena in their wake; it follows, incidentally, that activity chains are central to analyzing how social change affects life courses (cf. Elder, 1985). Yet, life trajectories also provide the activities that compose these chains. In thus providing much of the matter of social life, they are an indispensable presupposition, object, and point of intervention for the social disciplines.

The present essay has combined a phenomenologically-based account of life trajectories with a practice theoretical account of the constitutive social context through which they propagate. It thus sheds some light on what it means for lives to be “constituted” by practices. The advantage of a practice theoretical account in this context is that it provides a unified account of the variety of social contexts involved (including what Bernardi et al., 2019 call the “supra-individual level” of variables), for example, interactions with others, others’ activities, organizations, institutions, social changes, and longer-term processes. It thereby spares the analyst the error of hypostatizing, or setting on a distinct “level,” social entities such as organizations, institutions, and social changes and misconstruing how they govern. As a result, it offers to life course analysis a way of seamlessly integrating analysis of the phases and transitions of life with analyses of other social phenomena.