Matias Kimi Slavov

Metafysiikan Perusteet [The Basics of Metaphysics] is the first Finnish-language textbook on contemporary metaphysics. It contains introductions to the following issues: (i) what is metaphysics?, (ii) objects, properties and kinds, (iii) events and processes, (iv) metaphysical grounding, (v) modalities and essences, (vi) powers and causation, (vii) laws of nature, (viii) time, (ix) mathematics, (x) mind, (xi) free will, (xii) social ontology, (xiii) metaphysics of gender, (xiv) metaphysics in continental philosophy

Our dear friend and mentor Jani Hakkarainen reaches his half-century on December 23rd, 2025. Jani has been a constant presence for almost all of our academic lives. This includes, but is not limited to, his teaching, organizing the talk series at the Tampere University philosophy unit, arranging conferences on contemporary and historical philosophy, walking the corridors in his Tappara-slippers, stopping for an insightful chat at the coffee table, and often giving detailed, but always fair, criticism on our philosophical ideas and writings. In order to celebrate Janis’s birthday, we have invited a group of his colleagues and students to write articles on topics he has himself contributed to, or at least would find interesting and stimulating. This anthology is our birthday gift for him. The anthology is divided into five sections based on a larger theme of the papers, with these themes being related to one of the several fields of study Jani has partaken in during his philosophical career. It should be noted that, due to Jani’s love of 70’s progressive music, each section is titled after a song or a piece of lyric from a progressive rock band’s catalogue (including Genesis, Emerson Lake & Palmer, Rush, Pink Floyd, and King Crimson).

Conventional elements play an integral role in measuring time. Clocks unavoidably require a chosen standard of synchrony. The periodic process selected for the standard is not imposed upon us in any way. Conventionalism, in this regard, offers an insightful perspective on temporal measurement. The strong formulation of this doctrine is, however, questionable. After elaborating on strong conventionalism, it will be argued that it has three downsides: (i) it fails to properly distinguish between highly stable natural processes and complete randomness, as periodicities differ in terms of regularity; (ii) it does not explain that a clock actually measures something, to wit, parts of its own path along its worldline in spacetime; (iii) and relatedly, it omits the distinction between a temporal interval as a physical quantity and the arbitrarily chosen unit of time, leaving the distinction between temporal quantities and units a mystery.

This paper shall explore the conjunction of eternalism and Everettian quantum mechanics. It shall be argued that there is a strong analogy between these two views. In case there is an indefinite number of worlds and observers that are all equally real, there should be an indefinite number of local times which are all also equally real. Whereas Everettianism, specifically the diverging version, treats actuality indexically, relativistic eternalism treats tense indexically. All times exist analogously to all isolated Everettian worlds. There is no unique ‘now’ that cuts throughout all that physically exists. Instead, as eternalism propounds, all times exist. The paper concludes that eternalism and the many-worlds interpretation are not only compatible but complement each other, providing a coherent framework for understanding the nature of temporal reality.

Conventional elements play an integral role in measuring time. Clocks unavoidably require a chosen standard of synchrony. The periodic process selected for the standard is not imposed upon us in any way. Conventionalism, in this regard, offers an insightful perspective on temporal measurement. The strong formulation of this doctrine is, however, questionable. After elaborating on strong conventionalism, it will be argued that it has three downsides: (i) it fails to properly distinguish between highly stable natural processes and complete randomness, as periodicities differ in terms of regularity; (ii) it does not explain that a clock actually measures something, to wit, parts of its own path along its worldline in spacetime; (iii) and relatedly, it omits the distinction between a temporal interval as a physical quantity and the arbitrarily chosen unit of time, leaving the distinction between temporal quantities and units a mystery.

This paper shall explore the conjunction of eternalism and Everettian quantum mechanics. It shall be argued that there is a strong analogy between these two views. In case there is an indefinite number of worlds and observers that are all equally real, there should be an indefinite number of local times which are all also equally real. Whereas Everettianism, specifically the diverging version, treats actuality indexically, relativistic eternalism treats tense indexically. All times exist analogously to all isolated Everettian worlds. There is no unique ‘now’ that cuts throughout all that physically exists. Instead, as eternalism propounds, all times exist. The paper concludes that eternalism and the many-worlds interpretation are not only compatible but complement each other, providing a coherent framework for understanding the nature of temporal reality.

According to a widespread view, Einstein’s definition of time in his special relativity is founded on the positivist verification principle. The present paper challenges this received outlook. It argues that Einstein’s position on the concept of time, to wit, simultaneity, is best understood as a mitigated version of concept empiricism. He contrasts his position to Newton’s absolutist and Kant’s transcendental arguments, and in part sides with Hume’s and Mach’s empiricist arguments. Nevertheless, Einstein worked out a concept empiricism that is considerably more moderate than what we find in the preceding empiricist tradition and early logical positivism. He did not think that the origin of concepts is in observations, but in conventions, and he also maintained a realist ontology of physical events, which he thought is necessary for his theory. Consequently, his philosophy of time in special relativity is not couched in terms of an antimetaphysical verificationism.

This article centers on Hume's position on the intelligibility of natural philosophy. To that end, the controversy surrounding universal gravitation shall be scrutinized. It is very well known that Hume sides with the Newtonian experimentalist approach rather than with the Leibnizian demand for intelligibility. However, what is not clear is Hume's overall position on the intelligibility of natural philosophy. It shall be argued that Hume declines Leibniz's principle of intelligibility. However, Hume does not eschew intelligibility altogether; his concept of causation itself stipulates mechanical intelligibility.

This article investigates the relationship between Hume’s causal philosophy and Newton’s philosophy of nature. I claim that Newton’s experimentalist methodology in gravity research is an important background for understanding Hume’s conception of causality: Hume sees the relation of cause and effect as not being founded on a priori reasoning, similar to the way that Newton criticized non-empirical hypotheses about the properties of gravity. However, according to Hume’s criteria of causal inference, the law of universal gravitation is not a complete causal law, since it does not include a reference either to contiguity or to temporal priority. It is still argued that because of the empirical success of Newton’s theory—the law is a statement of an exceptionless repetition—Hume gives his support to it in interpreting gravity force instrumentally as if it bore a causal relation to motion.

Eternalism is a metaphysical view regarding the nature of time. It posits the equal existence of all times: the past, the present, and the future. Every event, from the big bang to the heat death of the universe, including our births and deaths, is equally real. Under standard eternalism, temporal locations are somewhat akin to spatial locations. No place is exclusively real. When someone says that they stand ‘here’, it is clear that the term ‘here’ refers to their position. ‘Back’ and ‘front’ exist as well. Eternalists stress that ‘now’ is indexical in a similar way. It is equally real with ‘past’ and ‘future’. Events are classified as past, present, or future from some perspective. Eternalism is contrasted with presentism, which maintains that only present things exist and with the growing block view (also known as possibilism or no-futurism), which holds that past and present things exist but not future ones. The moving spotlight view suggests that all times exist but that the present is the only actual time. This view can be termed eternalist, but it preserves a non-perspectival difference between past, present, and future by treating tense as absolute. Additionally, the moving spotlight view retains some characteristics of presentism by maintaining that the ‘now’ is unique and privileged. Broadly speaking, presentism is a common-sensical view, and so aligns with our manifest image of time. This view is, however, at odds with the scientific image of time. The primary motivation for eternalism arises from orthodox interpretations of the theories of relativity. According to them, simultaneity is relative, not absolute. This implies that there is no universal ‘now’ stretched out across the entire universe. One observer’s present can be another’s past or future. Assuming the universe is four-dimensional spacetime, then all events exist unconditionally. The classical argument for eternalism was devised in the 1960s by Rietdijk in 1966 and Putnam in 1967, with subsequent follow-ups by Maxwell in 1985, Penrose in 1989, and Peterson and Silberstein in 2010. This argument and its ramifications remain the subject of ongoing debate. They shall be further explored in this entry, including their relation to other issues in the metaphysics of time and the philosophy of physics.

Adrian Bardon has produced a new version of his historical introduction to the philosophy of time. Originally published in 2013, the second edition of 2024 is partly rewritten and supplemented with a more extensive discussion on our disposition to project the passage of time [...] Although the book’s title emphasizes history, most of the chapters are directed at issues in systematic philosophy of time: the realism/antirealism debate, temporal passage, temporal experience, spacetime, direction, time travel, time and free will, and the temporal boundaries of the universe.

Eternalism is the view that all times are equally real. The relativity of simultaneity in special relativity backs this up. There is no cosmically extended, self-existing ‘now.’ This leads to a tricky problem. What makes statements about the present true? I shall approach the problem along the lines of perspectival realism and argue that the choice of the perspective does. To corroborate this point, the Lorentz transformations of special relativity are compared to the structurally similar equations of the Doppler effect. The ‘now’ is perspectivally real in the same way as a particular electromagnetic spectrum frequency. I also argue that the ontology of time licensed by perspectival realism is more credible in this context than its current alternative, the fragmentalist interpretation of special relativity.

Ajan luonnetta koskevissa käsityksissä on tyypillistä erottaa kaksi eriävää kantaa: A-teoreettinen presentismi ja B-teoreettinen eternalismi. Edeltävän väitetään tyypillisesti sopivan yhteen inhimillisen ajallisen kokemuksen kanssa ja jälkimmäisen ontologisesti perustavanlaatuisen luonnontieteen kanssa. Ilmikuvamme ajasta sisältää ehdottoman nykyisyyden ja yksisuuntaisen ajan kulun menneestä tulevaan. Tieteellinen kuva ajasta ei sisällä erityistä nykyisyyttä eikä ajan kulun edellyttämää dynaamista aikamuotojen muutosta. Monet ovat pitäneet kokemustamme ajan kulusta illuusiona. Tässä artikkelissa keskitytään A-sarjan mukaisen ajankulun virheteoreettiseen tulkintaan. Tarkastellaan mahdollisuutta, jonka mukaan meillä ei ole kyseistä kokemusta vaan kuvailemme kokemustamme virheellisesti ajan virtaukseen liittyvillä vertauskuvilla. Tätä tukee fysikalistinen argumentti: Jos ajan kulun kokemuksellamme ei ole fysikaalista perustaa, meillä ei voi olla sen mukaista kokemustakaan ajasta.

If you were to list the perennial issues in philosophy, the nature of time would no doubt be on that list. The essays in the present volume all touch upon the problem of time. The volume includes four contributions from different perspectives within the history of philosophy of time.Jani Hakkarainen and Todd Ryan delve into David Hume's account of time. Hume thinks there can be no time without succession. Consequently, unchanging, steadfast objects do not have a duration. They are stationary, not subject to any change. Although they lack a duration, they coexist with a temporal succession. This introduces a problem: What is the relation between unchanging objects and time? Hakkarainen and Ryan draw on what they call Hume's Principle of Quantitative Comparison. Each indivisible temporal extent is equal to any other temporal extent; differences in duration are due to the different number of temporal parts. Steadfast objects may be thought to undergo a certain number of calculable changes when they are compared to ordinary successions we experience. This experience is provided, for example, by the ticking of a clock. We have the capacity to think that steadfast objects have precise durations. We humans nevertheless cannot give any deep explanation as how we come to this conclusion.Emily Thomas focuses on the graphic representation of time. Whereas the visual representation of time has typically been done with matrices or grids, Joseph Priestley represented time in a line in 1765. Priestley's line divides time “by an equal scale” into centuries. Many have interpreted this as being evidence of a Newtonian influence, as if there is an absolute time flowing equably. Thomas situates Priestley's position in the modern debates on the nature of our ideas. She argues that the absolutist reading does not have merit. Thomas thinks rather that Priestley sides with David Hartley, who explained how we acquire the ideas of duration and time from sensation. Thomas's essay advances our understanding of the history of space-time parallelism. With timelines, the analogy between time and space becomes a possibility. In my essay I assess Ernst Mach's criticism of Isaac Newton's substantivalist account of time. Newton's argument for absolute time relates to his mathematical-empirical physics and theology. In his Science of Mechanics, Mach largely neglects the laws of motion, calculus and the omnipresence theology that is at the background of Newton's concept of time. Mach did however criticize Newton's absolutist argument on the basis that the self-existing flow cannot be observed, measured, or experimented with, and he provided an alternative relational account of time. I point out that this was not only extreme positivism or phenomenalism, but an epistemology and ontology suited for the subsequent physical theories of relativity. Finally, I argue that Mach's denial of the independent atomic structure of matter should not be entirely assimilated to his denial of substantivalism about time. The two phenomena are different, so we should evaluate Mach's reasoning concerning them accordingly. Matyáš Moravec and Peter West go through Susan Stebbing's criticism of Arthur Eddington's popular account of the passage of time. Stebbing's target, Moravec and West argue, is Eddington's largely Bergsonian view on time. She objects to the view that our minds have “a private door” to the physical reality which no measurements can disclose. Stebbing believes that our experience of the passage of time belongs to our ordinary, every-day experience, and she thinks Eddington mystifies the whole idea by leaning on a peculiar form of introspection. Moravec and West build a case for Bergson's influence on Eddington, arguing that Bergson probably did contribute to Eddington's idea of “the intuition of becoming.” Both seem to think that we may access the dynamic temporal reality in ways not captured by scientific investigation, by means of an introspective internal experience of duration. As a final remark, I think I should note, with regret, that out of the six authors in this volume only one is a woman. Let the reader know that as an editor I tried to strike a better balance. I still trust that the quality of the articles is high, and most importantly, worthwhile for readers interested in the history of philosophy of time.

Mach repudiated Newton's argument for absolute time. He denied there is such a thing as time itself that exists independently of any external change. In doing so, Mach failed to appreciate Newton's scientific practice. Absolute time is intrinsically related to Newton's laws of motion and the method of fluxions. Commentators have noted similarities between Mach's rejection of Newtonian time and his rejection of the independent existence of atoms. In this article, it shall be argued that the juxtaposition of absolute time and the atomic theory is unsound. Mach had good reasons to question the existence of substantial time, and he went on to provide an alternative, ontologically relational account. Whereas his dismissal of atoms can be seen as a questionable form of “phenomenalism” or “positivism,” this is not the case regarding his position on time.

This book defends a relational theory of the passage of time. The realist view of passage developed in this book differs from the robust, substantivalist position. According to relationism, passage is nothing over and above the succession of events, one thing coming after another. Causally related events are temporally arranged as they happen one after another along observers’ worldlines. There is no unique global passage but a multiplicity of local passages of time. After setting out this positive argument for relationism, the author deals with five common objections to it: (a) triviality of deflationary passage, (b) a-directionality of passage, (c) the impossibility of experiencing passage, (d) fictionalism about passage, and (e) the incompatibility of passage with perduring objects.

This essay explores Kaila's interpretation of the special theory of relativity. Although the relevance of his work to logical empiricism is well-known, not much has been written on what Kaila calls the ‘Einstein-Minkowski invariance theory’. Kaila's interpretation focuses on two salient features. First, he emphasizes the importance of the invariance of the spacetime interval. The general point about spacetime invariance has been known at least since Minkowski, yet Kaila applies his overall tripartite theory of invariances to space, time and spacetime in an original way. Second, Kaila provides a non-conventionalist argument for the isotropic speed of electromagnetic signals. The standard Einstein synchrony is not a mere convention but a part of a larger empirical theory. According to Kaila's holistic principle of testability, which stands in contrast to the theses of translatability and verification, different items in the theory cannot be sharply divided into conventional and empirical. Kaila's invariantism/non-conventionalism about relativity reflects an interesting case in the gradual transition from positivism to realism within the philosophy of science.

Artikkelissa puolustetaan syy-seuraussuhteen ajallista yksisuuntaisuutta. Positiivinen argumentti perustuu ajanluontoisten tapahtumien ennen–jälkeen-suhteen pysyvyyteen. Olennaiset vastaväitteet, jotka perustuvat samanaikaiseen kausaliteettiin, antikausaaliseen fysiikan filosofiaan ja luonnonlakien symmetrisyyteen, otetaan huomioon. Johtopäätöksenä todetaan, että malliesimerkit kausaliteetista ilmentävät syyn ja seurauksen epäsymmetriaa. Syy alkaa ennen sen seurausta, vaikka ne ovat osittain samanaikaisia.

Eternalism is the view that the past, the present and the future exist simpliciter. A typical argument in favor of this view leans on the relativity of simultaneity. The ‘equally real with’ relation is assumed to be transitive between spacelike separated events connected by hyperplanes of simultaneity. This reasoning is in tension with the conventionality of simultaneity. Conventionality indicates that, even within a specific frame, simultaneity is based on the choice of the synchronization parameter. Hence the argument for eternalism is compromised. This paper lays out alternative eternalist strategies which do not hinge on hyperplanes. While we lack a rigorous proof for eternalism, there are still cogent reasons to prefer eternalism over presentism.

I argue that Hume’s philosophy of time is relationist in the following two senses. 1) Standard definition of relationism. Time is a succession of indivisible moments. Hence there is no time independent of change. Time is a relational, not substantial feature of the world. 2) Rigid relationism. There is no evidence of uniform natural standard for synchronization of clocks. No absolute temporal metric is available. There are countless times, and no time is privileged. Combining 1) and 2) shows that Hume’s ontology of time is thoroughly relationist.

To provide metaphysical grounds for the physics of her time, Du Châtelet argued for the notion of an active force. This was different from the impressed force in Newton’s second law. The former force was a property of a body, whereas the latter was an external cause. I shall study this discrepancy and argue that the interactive concept of force in Newton’s third law is consistent with Du Châtelet’s standards for an intelligible physics. Consequently, the interaction entailed by the law of universal gravitation complies with Du Châtelet’s principles of human knowledge.