It seems safe to say that we all act as though time is real. Time is central to our way of organising our day, our week, and indeed our lives.
But we mostly don’t give much thought to what time is really like, in itself.
Despite this, philosophers have often assumed that each of us has certain, probably tacit, beliefs about time.
Tacit beliefs are beliefs we have that guide our actions in various ways, but which we may never have consciously brought to mind.
So for instance, I’ve never consciously entertained the belief that were I to stand under a cold shower for 30 minutes, I would get extremely cold. Still, it’s fair to say that I tacitly have that belief. I act as though it’s true: I don’t stand under a cold shower for 30 minutes. If someone asked me whether that was a good idea, I would tell them ‘no’. If I wanted to get very cold, that is one method I might employ, and so on. We all have a lot of tacit beliefs. They guide our actions, and our other beliefs, but we might not consciously bring them to mind.
Philosophers have assumed that we have tacit beliefs about time, and that these shape our ways of engaging with the world. In particular, they have thought that we tacitly believe that there is something dynamical about time itself. Time is dynamical if there is a single moment that is the real, objective, present moment, and which moment that is, changes, so that times go from being future, to being present to being past. Most philosophers have thought this to be a pretty intuitive way to think about time. It seems natural to think that future events are getting closer to us by the present moment moving towards those events, while past events are moving away form us by the present moment moving away from them.
Many philosophers think that this intuitive picture is a big mistake, and that it leads us astray in various ways. For instance, some think that it is because we mistakenly think of ourselves, in the present, as moving towards the future, and away from the past, that we devalue past goods relative to future ones.
We know, for instance, that many people prefer to have bad things located in their past not their future, and good things located in their future not their past. When given a choice between more bad things happening in the past, and fewer bad things happening in the future, many people prefer that more bad things happened in the past. For instance they prefer that they had two terrible meals yesterday, than that they get one terrible meal tomorrow, even though that means they get twice as many terrible meals!
Whether or not you think that preference is rational, we want to know why we have preferences like these. If we think that our tacit beliefs about time play a role in our having preferences like these, then we need to know what those tacit beliefs are like. In particular, we want to know whether people tacitly believe that time is dynamical.
So, some colleagues and I decided to investigate people’s tacit beliefs about time. To do this we showed 600 people six different descriptions of time. Three of these described time as being dynamical in various ways, and three described time as not being dynamical. Then we asked people which of the descriptions is closest to describing time as it is in our world.
The idea is that even if people have never consciously thought about what time is like, if they have some sort of tacit picture, or representation, of time that they use to engage with the world, then they will be able to judge which of the various descriptions is most like the way they take time to be.
What we found was really interesting. About 70% of people think that time is dynamical, while 30% think it is not. So it may be that it is because many of us have these tacit beliefs, that we us prefer states of affairs that are worse for us, rather than better (like preferring two terrible meals yesterday, to one terrible meal today).
What was surprising was that when we look at the 70% of people who think time is dynamical, there is no agreement at all about in what ways time is dynamical.
We gave our participants three very different descriptions of dynamical time.
One of descriptions described time as being dynamical because only the present moment exists. Past and future moments don’t exist, and the present changes. Then time is dynamical because one and only present moment is constantly changing.
One of our descriptions described time as being dynamical because the present moment is the moment that has just come into existence. The present changes, on this view, because as time passes new moments come into existence, and the time that was present, becomes past. On this view the past exists, sitting ‘out there’ in spacetime, but the future does not yet exist. The present is the moment that sits at the edge of being as it is created.
Finally, we described a view on which all moments are equally real: there are past, present an future moments (and things at those moments). But time is dynamical because which moment is present, changes: the present moves from earlier moments to later moments, so that times go from being future, to being present, to being past.
Though 70% of people thought that time was dynamical in one of these ways, there was no agreement about whichway it is dynamical. People were split between these three ways of thinking about the dynamism of time. This suggests that there are really quite a lot of different tacit pictures of time, and that different people have different pictures. That’s important if we want to investigate the connection between people’s tacit beliefs about time, and the way they navigate the world, because people might be operating with quite different pictures of time.