Special Issue on “Time” in History of Philosophy Quarterly

Passage of time, at least the scientifically and metaphysically controversial notion of passage, means that the future approaches, turns into now, and then drifts off into the past.”

Introducing Volume 40, Issue 1 of History of Philosophy Quarterly, a special issue on the topic of time edited by Matias Slavov. Visit the Scholarly Publishing Collective to view the issue, listen to The UPside podcast hosted by Elizabeth Hess, or read the below transcript of the interview with Dr. Slavov. 

Elizabeth Hess: Thank you for joining us for the University of Illinois Press podcast, The UPside. I am your host, Elizabeth Hess. I am joined by Matias Slavov, the editor of the upcoming issue of the History of Philosophy Quarterly. Dr. Slavov is an Academy of Finland Post-Doctoral Fellow at Tampere University. Dr. Slavov, thank you so much for joining me today.  

Matias Slavov: Thank you for having me. 

EH: Before we get into the special issue, can you tell me a little bit about your history and your education and your research?  

MS: I did all my studies, from the Bachelor’s to the Master’s to the Doctoral degree, at the University of Jyväskylä. Jyväskylä is a city in Central Finland. Among others, I minored in Physics. After defending my PhD, I spent two years at UCLA in Los Angeles as a Visiting Scholar. There, I did research and taught a couple of undergrad courses.  

My research interests are threefold: the philosophy of time, including both contemporary debates about the nature of time and the history of the philosophy time, which is, of course, the topic of the forthcoming special issue we are about to discuss; then more generally, the history and philosophy of science, like issues in the history of philosophy of physics; and then, the philosophy of the Scottish enlightenment figure David Hume. 

EH: In the special issue, you say, “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.” What is an overview of the time-related topics we will find in this special issue? 

MS: The topic “time” is intentionally very loose. As an editor, I wanted to find something ranging from the classical Early Modern concept of time and the modern physical understanding of time, as introduced by relativity theory.  

Well, the time range is between the 18th and the 20th centuries, but the contributions focus on the views of individual philosophers. How does time fit in their overall philosophical systems? Here we are dealing with very specific parts of the philosophers’ views and the authors of the volume, they all aim to add a new interpretation to the extant literature. 

EH: Let’s talk about two of the contributors. Jani Hakkarainen and Todd Ryan study David Hume’s account of time in the article, “Hume on Time and Steadfast Unchanging Objects.” Hume thinks there can be no time without succession. Hakkarainen and Ryan draw on what they call Hume’s Principle of Quantitative Comparison. Tell me about what Hume meant by this, and why was Hakkarainen and Ryan’s assessment of his meaning so important.  

MS: This is already a very technical question. First, I have to say a couple of general things about Hume. He’s interested in the capacity of the human mind, in how we humans acquire ideas, like the idea of time. Hume is an empiricist who thinks our ideas come from sensory impressions. Our idea of time is hence not innate in any way: we humans do not have it when we are born, it must be originate in some impressions. All ideas need to be finite and distinct. According to Hume, we cannot conceive of anything infinitely large or infinitely small; we cannot have an idea of infinitesimals. So, objects of our thought are finite and distinct. So are the parts of time. We get our idea of time from perceivable change. Time is made of many items that are in a succession. For there to be time, the items need to be distinct so that there is some way to separate the different items.  

Think of musical chords—this is a typical example. An ongoing chord does not cause the idea of time. It’s not temporal in any way because there is nothing changing in such a sensible object. There should be a chord, another chord, pause, another chord, and so on. That’s how we abstract the notion of time and acquire information about temporal reality, by means of succession.  

Your question about quantitative comparison relates to the length of different times. Hume himself writes, “that time or duration consists of different parts: for otherwise we could not conceive of a longer or shorter duration.” So, this longer or shorter temporal extent, they presuppose temporal parts. What I take to be the main issue in Hakkarainen and Ryan’s paper is how to apply the idea of time to unchanging objects. This should, at first sight, be forbidden in Hume’s system, but we can nevertheless compare conceivable succession, like ticking of a clock, to some unchanging object, which is not itself the source for an idea of time.  

EH: Another contributor in this special issue, Emily Thomas, focuses on the graphic representation of time in “The Philosophy of Joseph Priestley’s 1765 Timeline: Abstract Ideas, Time, and Human Progress.” Thomas situates Priestley’s position in the modern debates on the nature of our ideas. She argues that this does not have any merit. Tell us about Dr. Thomas’ interpretation. Is that an accurate assessment of Priestley’s theories? 

MS: Thomas’s paper is fascinating because it really gets to the root of spatialization of time. For us today, at least for us who are acquainted at least with Einstein’s and Minkovsky’s fourth dimension relativity theory, we can think there is spacetime. Space is relative, time is relative, but there is an invariant structure: spacetime. The two cannot be sharply distinguished. But before that, when we go back a few centuries, how can you even begin to think that space and time are similar if you represent events on a timeline? So, Priestley found a way in 1765 to represent time in a line.  

Thomas, she really gets into the philosophical underpinnings and subsequent influence of Priestley’s timeline. The representation of time as uniform, it has usually been interpreted as being rooted in Newton’s absolute concept of time. Newton thought there is a time itself that flows equally no matter what, there are absolutely equal intervals of time, and this passage of time takes place without any reference to anything external, anything external of time itself. Thomas thinks that it’s true that Priestley’s representation of time is consistent with the Newtonian view, but she declines that it is grounded in it. Thomas meticulously examines the relevant Early Modern background of the theory of ideas and concludes that a physician and philosopher named David Hartley, who is actually a figure I did not know before reading the paper, is probably at the background of Priestley’s concept of time. 

EH: The article you wrote for the special issue, “Mach’s Denial of Absolute Time,” assesses Ernst Mach’s criticism of Isaac Newton’s substantivalist account of time. You say you point out that this was not only “extreme positivism or phenomenalism, but an epistemology and ontology suited for the subsequent physical theories of relativity.” Also, you argue that Mach’s denial of the independent atomic structure of matter should not be entirely assimilated to his denial of substantivalism about time. Please explain why you chose this particular viewpoint to dissect.  

MS: Mach repudiated Newton’s argument because Newton postulates a completely unobservable structure. So, in Mach’s view, it’s not connected to any kind of motion we can experience. For us to have any notion of time, we need some relative motion.  

Take for example, oscillations like that of a pendulum. Pendulums also exemplify clocks and even today we have some existing pendulum clocks. When we consider the pendulum in oscillation, we typically do not consider its relationship to the Earth. The oscillation is still related to the gravity of the Earth. In examining the pendulum swing, this is what Mach writes: “The illusory notion easily arises that all the things which we compare it are unessential.”  

Newton’s self-existing flow of time cannot be observed, measured, or experimented with. There’s no experiment in which you could use absolute time as a variable and somehow manipulate it. I think Mach’s critical outlook in this respect is very interesting and the alternative account of time, a relational account of time, influenced Einstein when he went on to devise his specialized and general theories of relativity. I must add here that Einstein was also keen on Hume. Hume was one of his favorite philosophers and he was even partly influenced by Hume in his argument for the relativity of simultaneity.  

Now, the case with atoms is different, because although atoms were not subject to observation and the question about the mind-independent existence of them is an interesting one from the viewpoint of the history of philosophy of science, the atomic theory certainly became testable in a great many ways. Nowadays, there’s no reasonable doubt about the existence of atoms. I mean, we wouldn’t really have contemporary physics, chemistry, and medicine, plus a bunch of technology, if they weren’t real. We couldn’t, for example, do this podcast without there being atoms.  

What I am arguing for in my essay is that sometimes Mach’s criticism of Newton’s account of time is dismissed because it’s based on extreme positivism or phenomenalism. They are roughly the thesis that only what you can verify in direct sense experience is meaningful and real. And then it might be pointed out that, well, atoms were not like this, you can’t prove they’re existent in such a way. What I’m saying is that this juxtaposition is unsound. Time and atoms are not a similar kind of phenomenon.  

EH: There are two contributors to the issue, Matyáš Moravec and Peter West, and they go through Susan Stebbing’s criticism of Arthur Eddington’s popular account of the passage of time. In their article, titled “Stebbing and Eddington in the Shadow of Bergson,” 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. 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.”  

What is the essence of their argument, and where do you side on this debate? 

MS: Passage of time, at least the scientifically and metaphysically controversial notion of passage, means that the future approaches, turns into “now,” and then drifts off into the past. This kind of notion of change in tense locations, meaning that the future changes from being future to being the present and then subsequently the present changes as being present to being past—this has been criticized for ages.  

When you go back to Parmenides, who is perhaps responsible for one of the earliest extended written philosophical argumentation about 2500 years ago, he already knows that the idea that the future, which is nothing, becomes the now, which is something, and then this something (the present moment) becomes the past, which is nothing—this is illogical. It cannot be that nothing becomes something and something becomes nothing. Many philosophers have thought and still do think that there is no passage of time, at least not in such a robust sense of temporal becoming. 

In Moravec’s and West’s paper, they know that Eddington, who was a practicing scientist himself, although he could not find any evidence for passage of time from physics, he thought that there is some kind of, perhaps a mystical intuition that can reveal parts of reality that, for instance, measurements cannot disclose. Now Stebbing strongly criticized such a view. For her, it was what she calls intuitional mysticism. A possible background for Eddington was Bergson’s theory of time that hinges on intuition of duration. This is the central argument in Moravec’s and West’s paper.  

As for me, you asked where do I stand in this debate. I don’t think there is passage of time in the robust sense and I do not think we humans experience time in the robust sense either. I, however, think passage of time is real, as there is succession of events along observer’s world lines. One thing comes after another objectively, and we humans experience temporal passage in a way that we experience things and thoughts succeeding each other.  

I would need more time to decipher this argument properly, of course, but it is actually the topic of my latest book that came out last summer. In it, I defend a qualified view of the reality of temporal passage that is intended to be both scientifically credible and hospitable to common sense.  

EH: Is it safe to say there is no correct side to this argument? It’s still evolving and it’s a matter of opinion and scientific fact backing up that opinion? 

MS: It’s a matter of philosophical and metaphysical debate. It’s been so for 2,500 years. Usually, the consensus would be that if you look at physics, you don’t really get a support for the idea of this kind of robust passage. As for my position, I think there is a scientific, a credible way to argue for passage of time, but not in this robust sense of changing, that there is this flow of time from future to the present and then to the past. 

EH: If you don’t mind me asking, since you talked about your research focusing on both physics and philosophy, sometimes those two viewpoints diverge. Physics is science, is concrete, philosophy can be opinion and a little more abstract. How do you combine those two studies and how do you pursue life’s answers with both of those two converging viewpoints? 

MS: That’s an excellent question. So, there’s a lot of discussion on the correct methodology within philosophy. I’m inclined to support some form of naturalism. The American philosopher Quine is a very famous proponent of philosophical naturalism. The idea is that science and philosophy are in a continuum and philosophy is really placed at the most abstract and general end of the spectrum, when you go from science to philosophy. So, I think these philosophical theories should be informed by science, but I don’t think you can reduce philosophical theories to physics, for instance. You still have issues like mind-independence, dependence, causation, supervenience, loss of nature, and whatnot. These kinds of concepts, it’s not like they can be reduced to physics or some special sciences. But I don’t believe in pure armchair philosophy, if you will. I’m interested in my work finding theories that are informed by science.  

EH: There is only one female contributor in the special issue, which you address in the following statement in your introduction: “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.” Were there not a lot of submissions from women, or did they not agree to be in this issue or what exactly happened? 

MS: I solicited all the submissions. There was no open call for papers. I wanted to have a better gender balance, but I actually had three women philosophers decline the offer to submit to the special issue. I think it was a matter of not finding the time to write the articles, not a matter of a better fit. In the end, I think the most important thing is the quality of the papers and how interesting they’ll be for the reader. I sincerely hope they won’t be boring.  

EH: I don’t imagine they will be. Before I let you go, one more question. What other research projects or upcoming publications will you be a part of in the upcoming months or year? 

MS: I’m most interested in the prospects of eternalism. Eternalism is the view about the nature of time, about the general nature of time, according to which all times exist. The past, the present, and the future are all real. Every event between the Big Bang and the heat death of the universe—obviously now, I don’t know where it all began and where it’s all going to end, but let’s take these two as if they are the temporal boundaries of everything that exists. So, everything between these, including our births and deaths, is equally real. All events are spread across the four dimensional spacetime. Whether an event is past, present, or future, that’s a perspectival matter. This view about the nature of time is compatible with the orthodox interpretations of the theories of relativity. Both the specialized and general theory under the orthodox interpretation, they lack a universal moment “now” that cuts throughout the entire universe.  

And this much is rather well-known, but there are unanswered questions. So, where did this approach, the eternalist doctrine, where did this concept come from? What’s the relevant history of the concept?  

Now you could go back to I guess Medieval times and antiquity, both West and East, but, in my project, I’m more interested, I would like to focus on the notion of eternalism that’s inspired by modern physics. So, the relevant history is the 20th century history of philosophy. 

Then the second big question is: is eternalism drastically in conflict with our everyday temporal experience? So, it’s typically assumed that our everyday view of time, the person on the street’s view, is presentism—the present moment exists, the past does not exist anymore, the future does not yet exist; the past and the future, they do not exist. But then, there are—well, I am not sure whether this is correct—there are alternative theories that account for our experience of time, which are more eternalist friendly. So it might also be that we falsely believe that we experience time in the presentist’s sense.  

And finally, what about the cutting-edge research programs in physics, do they take eternalism seriously? When you consider quantum physics, you immediately run into the problem of perhaps the future is open and nonexistent. So, the famous “double slit” experiment, for example, there we have particles hitting the detector screen randomly and this would support the view that the future does not exist, it’s an open possibility. This also aligns with the more common sensical view. And if this is true, that the future does not exist, then eternalism would turn out to be false because according to eternalism, there’s as much reality to the future as there is to the past and the present.  

If I could answer these questions in a collaborative research project, I think we would have made some progress in understanding the perennial issue: what is time? Let’s see if I’ll acquire funding for this project. Time will tell.  

EH: Thank you for listening to The UPside, the University of Illinois Press Podcast. The special issue of the History of Philosophy Quarterly, “Time,” is available here. Matias Slavov, thank you so much for your time today.  

MS: Thank you and have a good one! 

About Kristina Stonehill