Philosophers use the image of a growing block to think about the nature of time. It is one of several images. The image captures the steady accretion of past events as present moments become past moments. On a growing block conception of time, only the past and present are real as the future has not yet been determined. It is genuinely open. Against this, we could set an image of time as static with all events past present and future laid out in a great line. This is called the B-series conception of time. The events are ordered relatively earlier or later than each other, but not essentially as past present and future as such. The present is where we are on the line, and past events are earlier than now and future events are later. On this conception, the future events are already there, so this picture seems inconsistent with the openness of the future. The future is fixed. A shrinking block would be a conception of time whereby only the future and present existed not the past. The block shrinks as each present moment disappears into the past. For completeness, let me mention the pure presentist position that holds that only the present moment and neither the past nor the future exists. The philosophy of time is fascinating because none of these positions seems obviously and unproblematically right.
I’ve had a couple of occasions recently to ask visiting speakers, experts on the philosophy of time, for their take on an intuitive aversion I feel for ‘growing block’ theories of time. It’s quite puzzling and disorientating, really, because philosophical arguments are often based on strongly held intuitions, as the following objection is for me, but no one else shares it. It’s like I hit a wall.
For me, there can be no question of the growing block or shrinking block conceptions of time. These positions are ruled out by “the principle of conservation of reality” (which is just a grandiose name for something I made up). Put crudely, I can’t accept these pictures because I want to know, for the growing block, where the new events come from, and for the shrinking block, where the events go to. This really is the naive question it seems to be.
The growing block conception envisages a steady accumulation of events. What’s an event? I assume it’s some kind of arrangement of objects, properties and times. Can an event contain an object that doesn’t exist as a part? Presumably not. What would it contain, if the object didn’t exist? (I used to believe in non-existent objects and when I did, all these ontological questions had a particular significance for me). So, for me anyway, it seems natural to say the event of Wellington and company defeating Napoleon and company at the battle of Waterloo contains among other things both Napoleon and Wellington, and so they exist if it does. They’re both dead of course, but they still exist on the growing block conception because the past is equally as real as the present. That doesn’t seem absurd to me. What seems absurd is that we could add more events to the past and go on adding. It is absurd because, on the growing block conception, only the past and present are real and nothing else exists (or nothing temporal exists -maybe eternal and abstract kinds of thing may exist, but they’re a separate issue). But if nothing else exists, then where do all the new events come from? They must come from nothing, and nothing comes from nothing. So I don’t seem how a growing block conception of time can possibly be right. As it were, the growing block conception of time tells us there is so much reality on Monday and nothing else, and then tells us on Tuesday that there is more reality. But where did that extra stuff come from if there was nothing else?
This is what I mean by the conservation of reality. There can be no changes in the amount of reality. I think the intuition is perfectly symmetric and it is just as absurd to think of existent present and future events ceasing to be when they become past. Where does that reality go to? I just can’t imagine it.
Like I said, no one sees the force in this, but it has me enthralled.