This article argues that the causal loops that occur in some time-travel scenarios and in certain solutions of the theory of relativity are no more mysterious than the infinitely descending causal chains familiar from Newtonian mechanics.

The most potentially powerful objection to the possibility oftime travel stems from the fact that it can, under the right conditions, give rise to closedcausal loops, and closed causal loops can be turned into self-defeating causal chains;folks killing their infant selves, setting out to destroy the world before they were born,and the like. It used to be thought that such chains present paradoxes; the receivedwisdom nowadays is that they give rise to physical anomalies in the form (...) of inexplicably correlated events. I argue against the received wisdom. I can find nothing in them that argues against the possibility (even, the probability) of time travel. (shrink)

What is our conception of the temporal priority of cause over effect? It is that a causal chain runs always in the earlier‐to‐later direction. Each link in the chain is a process, whose initiation is the immediate, and thus simultaneous, effect of the arrival at a particular stage of the process that constitutes the preceding link. It is the fact that it is the subsequent continuation of the process, once initiated, that calls for no explanation, which gives a temporal (...) direction to the causal chain. If there are causal chains running in the reverse as well as in the usual direction, there is a possibility of causal loops. (shrink)

According to Hugh Mellor in Real Time II (1998, Ch. 12), assuming the logical independence of causal facts and the 'law of large numbers', causal loops are impossible because if they were possible they would produce inconsistent sets of frequencies. I clarify the argument, and argue that it would be preferable to abandon the relevant independence assumption in the case of causal loops.

According to Hugh Mellor in Real Time II, assuming the logical independence of causal facts and the ‘law of large numbers’, causal loops are impossible because if they were possible they would produce inconsistent sets of frequencies. I clarify the argument, and argue that it would be preferable to abandon the relevant independence assumption in the case of causal loops.

It has sometimes been suggested that backwards time travel always incurs causal loops. I show that this is mistaken, by describing worlds where backwards time travel occurs and yet no causal loops occur. Arguments that backwards time travel can occur without causal loops have been given before in the literature, but I show that those arguments are unconvincing.

A common line of argument for the impossibility of closed causal loops is that they would involve causal paradoxes. The usual reply is that such loops impose heavy consistency constraints on the nature of causal connections in them; constraints that are overlooked by the impossibility arguments. Hugh Mellor has maintained that arguments for the possibility of causal loops also overlook some constraints, which are related to the chances (single-case, objective probabilities) that causes give (...) to their effects. And he argues that a consideration of these constraints demonstrates that causal loops are impossible. I consider Mellor's argument and more generally the nature of chance in causal loops. I argue that Mellor's line of reasoning is unwarranted since it is based on untenable premisses about the relation between chances and long-run frequencies in causal loops. Yet, this line of reasoning may still be of interest to those who maintain that causes determine the chances of their effects; for it raises some unresolved questions about the nature of chance in causal loops. (shrink)

There have been many objections to the possibility oftime travel. But all the truly interesting ones concern the possibility of reversecausation. What is objectionable about reverse causation? I diagnose that the trulyinteresting objections are to a further possibility: that of causal loops. I raisedoubts about whether there must be causal loops if reverse causation obtains; but devote themajority of the paper to describing, and dispelling concerns about, various kinds ofcausal loop. In short, I argue that they (...) are neither logically nor physically impossible.The only possibly objectionable feature that all causal loops share is that coincidenceis required to explain them. Just how coincidental a loop will be varies: some arereally quite ordinary, and some are incredibly unlikely. I end by speculating thatthe tendency amongst physicists to avoid discussion of causal loops involving intentionalaction may have been unfortunate, since intentional action is an excellent way tonon-mysteriously bring about what otherwise would have been an unlikely coincidence. Hencecausal loops may be more likely in a world with beings like us, than in one without. (shrink)

Tim Maudlin’s argument for the inconsistency of Cramer’s Transactional Interpretation (TI) of quantum theory has been considered in some detail by Joseph Berkovitz, who has provided a possible solution to this challenge at the cost of a significant empirical lacuna on the part of TI. The present paper proposes an alternative solution in which Maudlin’s charge of inconsistency is evaded but at no cost of empirical content on the part of TI. However, Maudlin’s argument is taken as ruling out Cramer’s (...) heuristic “pseudotime” explanation of the realization of one transaction out of many. (shrink)

Tim Maudlin's argument for the inconsistency of Cramer's Transactional Interpretation of quantum theory has been considered in some detail by Joseph Berkovitz, who has provided a possible solution to this challenge at the cost of a significant empirical lacuna on the part of TI. The present paper proposes an alternative solution in which Maudlin's charge of inconsistency is evaded but at no cost of empirical content on the part of TI. However, Maudlin's argument is taken as ruling out Cramer's heuristic (...) "pseudotime" explanation of the realization of one transaction out of many. (shrink)

The doctrine of the immaculate conception, which is a dogma binding on all Roman Catholics and also held by members of some other Christian denominations, holds that Mary the mother of Jesus Christ was conceived without the stain of original sin as a result of the redeeming effects of Christ’s later life, passion, death, and resurrection. In this paper I argue first that, even on an orthodox reading of this doctrine, the immaculate conception seems to result in a kind of (...) causal time loop. I then consider several common philosophical objections to causal time loops, showing how each is either not a serious problem for causal time loops in general or is not a serious problem for the immaculate conception time loop in particular because of some particular features of that particular loop. The upshot of this discussion is that it shows that anyone who is committed to the dogma of the immaculate conception is also committed to the possibility, and, indeed, the actuality, of at least one causal time loop, but also that this is no reason to reject the dogma, since all of the major worries for causal time loops can be resolved in one way or another. (shrink)

Montesquieu's Considérations sur les causes de la grandeur des Romains et de leur décadence (1733/1734) is a methodological exercise in causal explanation on the meso-level applied to the subject of the military rise and fall of Rome. Rome is described as a system with contingent initial conditions that have a strong path-determining effect. Contingent and plastic initial configurations become highly determining in their subsequent operation, thanks to self-reinforcing feedback loops. Montesquieu's method seems influenced by the ruthless commitment to (...) efficient causality and the reductionism of seventeenth-century mechanicist philosophy; but in contrast to these predecessors, he is more interested in dynamic processes than in unchangeable substances, and his use of efficient causality in the context of a system approach implies a form of holism that is lacking in his predecessors. The formal and conceptual analysis in this article is in many ways complementary with Paul Rahe's recent predominantly political analysis of the Considérations. At the same time, this article points to a problem in the works on the Enlightenment by Jonathan Israel: his account stresses a one-dimensional continuum consisting of Radical, Moderate and Counter-Enlightenment. This invites Israel to place the combined religious, political and philosophical views of each thinker on one of these three points. His scheme runs into trouble when a thinker with moderate religious and political views produces radical philosophical concepts. Montesquieu's Considérations is a case in point. (shrink)

The ‘causal-constitution’ fallacy, the ‘cognitive bloat’ worry, and the persisting theoretical confusion about the fundamental difference between the hypotheses of embedded (HEMC) and extended (HEC) cognition are three interrelated worries, whose common point—and the problem they accentuate—is the lack of a principled criterion of constitution. Attempting to address the ‘causal-constitution’ fallacy, mathematically oriented philosophers of mind have previously suggested that the presence of non-linear relations between the inner and the outer contributions is sufficient for cognitive extension. The abstract (...) idea of non-linearity, however, can be easily misunderstood and has, in the past, led to incorrect and counterintuitive conclusions about what may count as part of one’s overall cognitive system. In order to prevent any further mistakes I revisit dynamical systems theory to study the nature of the continuous mutual interactions that give rise to the aforementioned non-linear relations. Moreover, focusing on these interactions will allow us to provide two distinct arguments in support of the ontological postulation of extended cognitive systems, as well as an objective criterion of constitution. Accordingly, I put forward a version of HEC that treats continuous mutual interactions (and the resultant non-linear relations) not just as sufficient but also as necessary for cognitive extension. Such a qualified version of HEC may exclude certain alleged cases of cognitive extension where the agent does not mutually interact with his artifacts (e.g., shopping lists and directory services), but it is immune both to the ‘causal-constitution’ fallacy and the ‘cognitive bloat’ worry, and it can be sharply distinguished from HEMC. (shrink)

Real causal systems are complicated. Despite this, causal learning research has traditionally emphasized how causal relations can be induced on the basis of idealized events, i.e. those that have been mapped to binary variables and abstracted from time. For example, participants may be asked to assess the efficacy of a headache-relief pill on the basis of multiple patients who take the pill (or not) and find their headache relieved (or not). In contrast, the current study examines learning (...) via interactions with continuous dynamic systems, systems that include continuous variables that interact over time (and that can be continuously observed in real time by the learner). To explore such systems, we develop a new framework that represents a causal system as a network of stationary Gauss--Markov (``\OU'') processes and show how such \textit{OU networks} can express complex dynamic phenomena such as feedback loops and oscillations. To assess adult's abilities to learn such systems, we conducted an experiment in which participants were asked to identify the causal relationships of a number of OU networks, potentially carrying out multiple, temporally-extended interventions. We compared their judgments to a normative model for learning OU networks as well as a range of alternative and heuristic learning models from the literature. We found that, although participants exhibited substantial learning of such systems, they committed certain systematic errors. These successes and failures were best accounted for by a model that describes people as focusing on pairs of variables, rather than evaluating the evidence with respect to the full space of possible structural models. We argue that our approach provides both a principled framework for exploring the space of dynamic learning environments as well as new algorithmic insights into how people interact successfully with a continuous causal world. (shrink)

In this article, I explore the role of affective feedback loops in creating and sustaining trust and distrust. Some emotions, such as fear and contempt, drive out trust; others, such as esteem and empathy, drive out distrust. The mechanism here is causal, but not merely causal: affective looping works through changing how the agent interprets the words, deeds, and motives of the other, thus making trust or distrust appear justified. Looping influences not only dyadic trust, but also (...) climates, and networks of trust and distrust. Not all trust-entrenching looping is virtuous, nor all distrust-entrenching looping vicious, but distrust looping is a powerful way to justify xenophobic public policy. I explore options for remedy. (shrink)

Introduction -- Simple linear causality : one thing makes another happen -- The cognitive science of simple causality : why do we get stuck? -- Domino causality : effects that become causes -- Cyclic causality : loops and feedback -- Spiraling causality : escalation and de-escalation -- Mutual causality : symbiosis and bi-directionality -- Relational causality : balances and differentials -- Across time and distance : detecting delayed and distant effects -- "What happened?" vs. "what's going on?" : thinking (...) about steady states -- What you can't see does matter : attending to obvious and non-obvious causes -- It's not always a case of who did it : minding passive and unintentional causality -- Step by step, or not : the mind-bending concept of simultaneous causality -- Figuring out what to count on : dealing with stochastic causality -- Isn't anybody in charge around here? : attending to distributed causality and emergence -- Summing up : the implications for helping a new generation understand causal complexity -- Putting it all together : teaching for causal complexity. (shrink)

Causal loops are a recurring feature in the philosophy of time travel, where it is generally agreed that they are logically possible but may come with a theoretical cost. This paper introduces an unfamiliar set of causal loop cases involving knowledge or beliefs about the future: self-fulfilling prophecy loops (SFP loops). I show how and when such loops arise and consider their relationship to more familiar causal loops.

Chronic myeloid leukemia (CML) is a cancer of the hematopoietic system initiated by a single genetic mutation which results in the oncogenic fusion protein Bcr-Abl. Untreated, patients pass through different phases of the disease beginning with the rather asymptomatic chronic phase and ultimately culminating into blast crisis, an acute leukemia resembling phase with a very high mortality. Although many processes underlying the chronic phase are well understood, the exact mechanisms of disease progression to blast crisis are not yet revealed. In (...) this paper we develop a mathematical model of CML based on causal Bayesian networks in order to study possible disease progression mechanisms. Our results indicate that an increase of Bcr-Abl levels alone is not sufficient to explain the phenotype of blast crisis and that secondary changes such as additional mutations are necessary to explain disease progression and the poor therapy response of patients in blast crisis. (shrink)

By definition, metacognitive processes may monitor or regulate various stages of first-order processing. By combining causal analysis with hypotheses expressed by other authors we derive the theoretical and methodological consequences of this special relation between metacognition and the underlying processes. In particular, we prove that because multiple processing stages may be monitored or regulated and because metacognition may form latent feedback loops, 1) without strong additional causal assumptions, typical measures of metacognitive monitoring or regulation are confounded; 2) (...) without strong additional causal assumptions, typical methods of controlling for first-order task performance (i.e., calibration, staircase, including first-order task performance in a regression analysis, or analyzing correct and incorrect trials separately) not only do not deconfound measures of metacognition but may even introduce bias; 3) that the first two problems cannot be solved by using simple models of decision-making derived from Signal Detection Theory. We conclude the paper by advocating robust methods of discovering properties of latent mechanisms. (shrink)

The analyses of explanation and causal beliefs are heavily dependent on using probability functions as models of epistemic states. There are, however, several aspects of beliefs that are not captured by such a representation and which affect the outcome of the analyses. One dimension that has been neglected in this article is the temporal aspect of the beliefs. The description of a single event naturally involves the time it occurred. Some analyses of causation postulate that the cause must not (...) occur later than the effect. If we want this kind of causality it is easy to add the appropriate clause to ( CAUS ). An alternative is not to rule out backwards causation or causal loops a priori , but expect that ( CAUS ), via the properties of the contraction P C - , will result in the desired temporal relation between C and E . One way of ensuring this is to postulate that when the probability function P is contracted to P C - , the probabilities of all events that occurred before C remain the same in P C - as in P . This means that all beliefs about the history of events up to C are left unaltered in the construction of the hypothetical state of belief P C - . In conclusion, I hope to have shown that, in spite of these limitations, ( EXP ) and ( CAUS ) provide viable analyses of explanation and causality between single events for the case when epistemic states can be described by probability functions. I have also shown that the two analyses can be used to explicate the close connections between the two notions. These analyses reduce the problems of explanation and causality, hopefully in a non-circular way, to the problem of identifying contractions of states of belief. (shrink)

Recording and manipulating neuronal ensemble activity is a key requirement in advanced neuromodulatory and behavior studies. Devices capable of both recording and manipulating neuronal activity brain-computer interfaces should ideally operate un-tethered and allow chronic longitudinal manipulations in the freely moving animal. In this study, we designed a new intracortical BCI feasible of telemetric recording and stimulating local gray and white matter of visual neural circuit after irradiation exposure. To increase the translational reliance, we put forward a Göttingen minipig model. The (...) animal was stereotactically irradiated at the level of the visual cortex upon defining the target by a fused cerebral MRI and CT scan. A fully implantable neural telemetry system consisting of a 64 channel intracortical multielectrode array, a telemetry capsule, and an inductive rechargeable battery was then implanted into the visual cortex to record and manipulate local field potentials, and multi-unit activity. We achieved a 3-month stability of the functionality of the un-tethered BCI in terms of telemetric radio-communication, inductive battery charging, and device biocompatibility for 3 months. Finally, we could reliably record the local signature of sub- and suprathreshold neuronal activity in the visual cortex with high bandwidth without complications. The ability to wireless induction charging combined with the entirely implantable design, the rather high recording bandwidth, and the ability to record and stimulate simultaneously put forward a wireless BCI capable of long-term un-tethered real-time communication for causal preclinical circuit-based closed-loop interventions. (shrink)

The causal structure of Darwinian evolution by natural selection is investigated. Its basic scheme is reproduction resulting from a feedback loop driven by internal and external causes. Causation internal to the loop connects genotype, development, phenotype, and fitness, with environmental constraints on the latter preventing runaway reproduction. External causes driving the core loop are environmental change and genetic change. This basic causal structure is complicated by modern additions such as control of mutation rate, niche construction, interactions between evolution (...) and development, and epigenetic effects. In this article it is argued that at least one of these additions, control of mutation rate, produces an additional feedback loop incorporating a continual, targeted modulation of stochasticity, and thereby produces an unusual form of causation. This form of causation entangles deterministic and stochastic causation in such a way that it imposes, in effect, an active, goal-driven role on the organisms in a line of descent. The goal is defined by the factor driving the stochasticity, which must be regarded as an intrinsic estimate made implicitly by the organism of its own fitness. The estimator itself is an evolved property of the organism, and is aligned with the apparent goal-directedness of natural selection. (shrink)

Increasing evidence suggests that it is not only the case that brain-based cognitive and emotional processes affect decision-making, but also that decision-making, actions and habits influence in turn the very structure and function of the brain by way of neural plasticity. This indicates that the interplay between brain and agency is made up of a complex feedback loop of reciprocal causality. The assumption that the causal relationship is one way –brain to behavior– results in unsatisfactory neuroscientific analyses of agency. (...) I contend that taking into account reciprocal causality for the purposes of human enhancement is not only a matter of theoretical consistency, but also carries with it important practical implications. Top-down cognitive enhancement –through mind training techniques such as meditation– may have advantages over biomedical enhancement. (shrink)

A meaningful distinction can be made between functions and mere effects in biological systems without resorting to teleological arguments: (i) biological systems must cope with a multitude of problems or they will cease to exist; (ii) the solutions to these problems invariably depend on circular causal chains (“feedback loops”); and (iii) biological functions are attributes of elements in biological systems that have an effect which, by contributing to the correcting behavior of a feedback control system, assists in solving (...) a biological problem. The analysis is applied to several biological systems. The proposed solution is discussed primarily in its relation to two popular approaches to the concept of biological function, i.e., the “causal role accounts” and the “selected effect accounts”. (shrink)

It is time that we in organization sciencesdevelop and implement a new mental model forcause and effect relationships. The dominantmodel in research dates at least to the 1700sand no longer serves the full purposes of thesocial science research problems of the21st century. Traditionally, research is``essentially concerned with two-variableproblems, linear causal trains, one cause andone effect, or with few variables at the most''(von Bertalanffy, 1968, p. 12). However, theliterature is replete with examples ofphenomena in which the traditional cause andeffect construct (...) does not allow for greaterunderstanding and insight into the phenomena. Different conceptions of cause and effectrelationships have been developed includingproducer/product relationships (Ackoff 1981),design causality (Argyris and Schon, 1996), andfour classes of causal models (Schwartz andOgilvy, 1979). Of interest here is thepossibility of mutual causality, ``theassumption that the relationship between two(or more) phenomena is heavily influenced bythe presence of feedback loops that areinstantaneous, or nearly so'' (Dent, 1999). Maturana's (1998, Maturana and Varela, 1987)work on a new epistemology and ontologyprovides a foundation for the alternative modelof cause and effect proposed here. Thisinteraction model includes the dynamics of thetraditional X and Y, but adds the structure ofX (A), the structure of Y (B), the environment(E), and time (T). (shrink)

Michael Dummett is a leading contemporary philosopher whose work on the logic and metaphysics of language has had a lasting influence on how these subjects are conceived and discussed. This volume contains some of the most provocative and widely discussed essays published in the last fifteen years, together with a number of unpublished or inaccessible writings. Essays included are: "What is a Theory of Meaning?," "What do I Know When I Know a Language?," "What Does the Appeal to Use Do (...) for the Theory of Meaning?," "Language and Truth," "Truth and Meaning," "Language and Communication," "The Source of the Concept of Truth," "Mood, Force, and Convention," "Frege and Husserl on Reference," "Realism," "Existence," "Does Quantification Involve Identity?," "Could there be Unicorns?," "Causal Loops," "Common Sense and Physics," "Testimony and Memory," "What is Mathematics About?," "Wittgenstein on Necessity: Some Reflections," and "Realism and Anti-Realism." Serving well as a companion to Dummett's other collections, the essays in this volume are not forbiddingly technical or specialized, and have relevance to many areas of analytic philosophy. (shrink)

It has been suggested that there is something worrisome, puzzling, or incomprehensible about the sorts of causal loops sometimes involved in backwards time travel. This paper disentangles two distinct puzzles and evaluates whether they provide us reason to find backwards time travel incomprehensible, inexplicable, or otherwise worrisome. The paper argues that they provide no such reason.

It is not uncommon in time travel stories to find that the mechanism by which the time travel is achieved is not invented. A time traveller could journey to his/her own past and give the designs of the time travel machine to his/her earlier self as s/he was given the designs as a younger person. These designs never get thought up by anyone. Such a situation would conflict with the usual conception of the acquisition of knowledge. This situation is called (...) the Temporal Epistemic Anomaly and would arise if knowledge is gained at a time prior to the information in question being transmitted but is not discovered or invented at any time. This article examines the implications of information propagating around a causal chain that is closed in time (which is required to create the Anomaly) and whether this information need have a specific origin point. (shrink)

WREEN'S PROPOSAL FOR AVOIDING CAUSAL LOOPS IN THE DESCRIPTION OF ACTION IS, I ARGUE, ITSELF LOOPY.

This book develops a novel argument which combines the Kalam with the Thomistic Cosmological Argument. It approaches an ongoing dispute concerning whether there is a First Cause of time from a radically new point of view, namely by demonstrating that there is such a First Cause without requiring the controversial arguments against concrete infinities and against traversing an actual infinite (although the book presents original defenses of these arguments as well). This book also develops a novel philosophical argument for the (...) Causal Principle, namely that ‘everything that begins to exist has a cause’, and offers a detailed discussion on whether a First Cause of time can be avoided by a causal loop. It also addresses epistemological issues related to the Cosmological Argument which have been relatively neglected by recent publications, and demonstrates (contra Hawking et al) the continual relevance and significance of philosophy for answering ultimate questions. -/- . (shrink)

I assess various proposals for the source of the intuition that there is something problematic about contextuality, ultimately concluding that contextuality is best thought of in terms of fine-tuning. I then argue that as with other fine-tuning problems in quantum mechanics, this behaviour can be understood as a manifestation of teleological features of physics. Finally I discuss several formal mathematical frameworks that have been used to analyse contextuality and consider how their results should be interpreted by scientific realists. In the (...) course of this discussion I obtain several new mathematical results—I demonstrate that preparation contextuality is a form of fine-tuning, I show that measurement contextuality can be explained by appeal to a global constraint forbidding closed causal loops, and I demonstrate how negative probabilities can arise from a classical ontological model together with an epistemic restriction. (shrink)

Michael Dummett and Storrs McCall have claimed that time travel scenarios in which an artist copies an artwork from a reproduction of it that has been sent from the future introduce a causal loop of a new kind: one involving artistic value. They have suggested that this poses a hitherto unacknowledged challenge to time travel theories. I argue that their conclusion depends on some unstated essentialist assumptions about metaphysics of art and the status of representations. By relaxing these assumptions, (...) I show that Dummett and McCall’s scenarios contain no causal loop involving artistic value, and thus pose no new problem for time travel theories. (shrink)

In mental action there is no motor output to be controlled and no sensory input vector that could be manipulated by bodily movement. It is therefore unclear whether this specific target phenomenon can be accommodated under the predictive processing framework at all, or if the concept of “active inference” can be adapted to this highly relevant explanatory domain. This contribution puts the phenomenon of mental action into explicit focus by introducing a set of novel conceptual instruments and developing a first (...) positive model, concentrating on epistemic mental actions and epistemic self-control. Action initiation is a functionally adequate form of self-deception; mental actions are a specific form of predictive control of effective connectivity, accompanied and possibly even functionally mediated by a conscious “epistemic agent model”. The overall process is aimed at increasing the epistemic value of pre-existing states in the conscious self-model, without causally looping through sensory sheets or using the non-neural body as an instrument for active inference. (shrink)

We examine three business-related initiatives designed to achieve peace positive impacts in the Cape Town township of Langa. Each was seemingly straightforward in its purpose, logic, and implementation. However, their positive intent was frustrated and their impacts ultimately harmful to their articulated goals. Understanding why this is so can be difficult in violent, turbulent, and information-poor environments such as Langa, confounding progress even by actors with ethical intentions. To aid in sense making and to provide insight for more positive future (...) action, we develop from 125 interviews conducted for this study causal loop models for these initiatives within their conflict subsystems. These explain the perverse impacts of these initiatives by illuminating their (lack of) salience to key conflict factors, their (in)sufficiency to effect positive change in light of competing systems dynamics, and their (in)attentiveness to interdependencies with the intentions and actions of others. We thus contribute to understanding of the factors required to achieve positive social outcomes in more extreme contexts. More generally, we demonstrate the value of systems analysis both for scholarship related to business and peace and for reducing blind spots that can inhibit sound planning for ethical business action amidst complexity. (shrink)

The topic is time travel of the sort depicted in H. G. Wells’ classic novel, The Time Machine—Wellsian time travel. The range of proper applicability of the concept of Wellsian time travel is investigated. The results of this investigation are applied to provide a new argument against the metaphysical possibility of time travel in absolute time. Alternatively, the argument is against the possibility of Wellsian time travel relative to a single temporal frame of reference. The argument leaves open the prospect (...) that an object nontrivially moves relative to one temporal reference frame from one time to another relative to another temporal reference frame. The argument does not turn on closed timelike curves or “causal loops” of any kind. It does however invoke the prospect of backward causation—a consequence of backward time travel in conjunction with common sense—but it invokes this possibility only in the weak sense of mere logical consistency. (shrink)

Talk about time travel is puzzling even if it isn't obviously contradictory. Philosophers however are divided about whether time travel involves empirical paradox or some deeper metaphysical incoherence. It is suggested that time travel requires a Parmenidean four-dimensionalist metaphysical conception of the world in time. The possibility of time travel is addressed (mainly) from within a Parmenidean metaphysical framework, which is accepted by David Lewis in his defence of the coherence of time travel. It is argued that time travel raises (...) formidable difficulties which are not satisfactorily resolved by Lewis's ingenious defence of time travel. Objections to time travel considered include: (1) travel to other times is impossible because there is nowhere (or “nowhen”) to go to; (2) the problem that upon setting out on a journey to the past a time machine will collide with itself; (3) time travel generates a mysterious temporal dualism between experiential time and physical time; (4) travel to the past permits reverse causation, raising the possibility of causal loops and attendant problems arising, for example, from the prospect of empirical contradiction and the possibility of someone being one of their ancestors. (shrink)

We review an argument that bipartite "PR-box" correlations, though designed to respect relativistic causality, in fact violate relativistic causality in the classical limit. As a test of this argument, we consider Greenberger-Horne-Zeilinger (GHZ) correlations as a tripartite version of PR-box correlations, and ask whether the argument extends to GHZ correlations. If it does-i.e., if it shows that GHZ correlations violate relativistic causality in the classical limit-then the argument must be incorrect (since GHZ correlations do respect relativistic causality in the classical (...) limit.) However, we find that the argument does not extend to GHZ correlations. We also show that both PR-box correlations and GHZ correlations can be retrocausal, but the retrocausality of PR-box correlations leads to self-contradictory causal loops, while the retrocausality of GHZ correlations does not. (shrink)

What is the relation between intelligence and computation? Although the difficulty of defining `intelligence' is widely recognized, many are unaware that it is hard to give a satisfactory definition of `computational' if computation is supposed to provide a non-circular explanation for intelligent abilities. The only well-defined notion of `computation' is what can be generated by a Turing machine or a formally equivalent mechanism. This is not adequate for the key role in explaining the nature of mental processes, because it is (...) too general, as many computations involve nothing mental, nor even processes: they are simply abstract structures. We need to combine the notion of `computation' with that of `machine'. This may still be too restrictive, if some non-computational mechanisms prove to be useful for intelligence. We need a theory-based taxonomy of {\em architectures} and {\em mechanisms} and corresponding process types. Computational machines my turn out to be a sub-class of the machines available for implementing intelligent agents. The more general analysis starts with the notion of a system with independently variable, causally interacting sub-states that have different causal roles, including both `belief-like' and `desire-like' sub-states, and many others. There are many significantly different such architectures. For certain architectures (including simple computers), some sub-states have a semantic interpretation for the system. The relevant concept of semantics is defined partly in terms of a kind of Tarski-like structural correspondence (not to be confused with isomorphism). This always leaves some semantic indeterminacy, which can be reduced by causal loops involving the environment. But the causal links are complex, can share causal pathways, and always leave mental states to some extent semantically indeterminate. (shrink)

This paper examines the stability of objective chance. I defend the stable chance thesis : that in any given possible world, any pair of intrinsic duplicate physical setups with the same chances of being subject to the same external influences must yield the same chances. I argue that SCT compares favourably to rivals in the literature. I then consider a challenge to SCT involving time travel and causal loops. I argue that SCT survives this challenge, but that such (...) cases expose chance as less stable than we might unreflectively have thought. In particular, the chances associated with a physical setup are sensitive to the way that this setup is embedded in a wider causal structure. (shrink)

The relation between quantum collapse, consciousness and superluminal communication is analyzed. As we know, quantum collapse, if exists, can result in the appearance of quantum nonlocality, and requires the existence of a pre- ferred Lorentz frame. This may permit the realization of quantum superluminal communication (QSC), which will no longer result in the usual causal loop in case of the existence of a preferred Lorentz frame. The possibility of the existence of QSC is further analyzed under the assumption that (...) quantum collapse is a real process. We demonstrate that the combination of quantum collapse and the consciousness of the observer will permit the observer to distinguish nonorthogonal states in principle. This provides a possible way to realize QSC. Some implications of the existence of QSC are briefy discussed. (shrink)

In 1987, Roy Sorensen coined the term “parahistory” to denote the hypothetical study of evidence retrieved via time travel. Parahistory would thus stand to history rather as parapsychology does to psychology; studying data (in this case artefacts) that are obtained in ways unrecognised by orthodox science. This paper considers future-derived parahistorical artefacts. Past/future asymmetries threaten irresolvable problems in calibrating future objects' periods, in dating future artefacts and insulating them from causal loops. In turn, causal loop objects at (...) best cannot be non-arbitrarily dated at all and at worst, cannot even be artefacts. Even if there can be evidence for travel from the future, any such evidence that appeals to future artefacts faces pervasive difficulties and is very unlikely to be compelling. (shrink)

This paper aims to establish that time travel into the past is, at best, highly improbable. It does this by first establishing the causal dependency of identity relations for a person or object travelling into the past. The paper then goes on to show how hard it is to avoid a closed causal loop in time travel experiments, and the inherently contradictory nature of said loops. It then raises the question of how such loops could be (...) avoided without affecting the identity requirements of the traveller, thus drawing the conclusion that while, strictly speaking, time travel has not been proved impossible, the combination of circumstance required to avoid contradiction is so unlikely as to render such activity highly improbable. (shrink)

In 1987, Roy Sorensen coined the term “parahistory” to denote the hypothetical study of evidence retrieved via time travel. Parahistory would thus stand to history rather as parapsychology does to psychology; studying data (in this case artefacts) that are obtained in ways unrecognised by orthodox science. This paper considers future-derived parahistorical artefacts. Past/future asymmetries threaten irresolvable problems in calibrating future objects' periods, in dating future artefacts and insulating them from causal loops. In turn, causal loop objects at (...) best cannot be non-arbitrarily dated at all and at worst, cannot even be artefacts. Even if there can be evidence for travel from the future, any such evidence that appeals to future artefacts faces pervasive difficulties and is very unlikely to be compelling. (shrink)

This paper proposes a limitation to epistemological claims to theory building prevalent in critical realist research. While accepting the basic ontological and epistemological positions of the perspective as developed by Roy Bhaskar, it is argued that application in social science has relied on sociological concepts to explain the underlying generative mechanisms, and that in many cases this has been subject to the effects of an anthropocentric constraint. A novel contribution to critical realist research comes from the work and ideas of (...) Gregory Bateson. This is in service of two central goals of critical realism, namely an abductive route to theory building and a commitment to interdisciplinarity. Five aspects of Bateson’s epistemology are introduced: difference, logical levels of abstraction, recursive causal loops, the logic of metaphor, and Bateson’s theory of mind. The comparison between Bateson and Bhaskar’s ideas is seen as a form of double description, illustrative of the point being raised. The paper concludes with an appeal to critical realists to start exploring the writing and outlook of Bateson himself. (shrink)

This paper examines various philosophical arguments to do with time travel. It argues that time travel has not been shown to be logically impossible. It then considers whether time travel would give rise to improbable strings of coincidences, or closed causal loops. Finally, it considers whether we could ever be justified in believing someone who claimed to be a time traveller, or whether we would always be more justified in believing that the claimant was either deluded or trying (...) to deceive us. For this last issue the Terry Gilliam film ‘Twelve Monkeys’ is used as an example. (shrink)

People frequently make ethical choices they later regret. Causal Loop Archetypes offer a basic systems framework for analyzing the unintended consequences of personal and professional ethical decisions. Pressure or enticement or defensiveness can stymie individuals’ rational sensemaking. Causal Loop Thinking, and in particular the “Fixes That Fail” Archetype, draw on the familiar decision model of identifying the problem, specifying the alternative courses of action andtheir consequences, to guide our final choice. As students grapple with their own conflicts and (...) business school faculty look for tools to anticipate professional ethical dilemmas, Causal Loop Thinking can expand our awareness of the context of choices and actions, thus leading to a more fully assessed decision. (shrink)