Posted by: dacalu | 24 November 2012

Two Roads

This semester, I’ve been looking at questions of cognitive neuroscience and free will with my graduate seminar.  It’s been a wonderful opportunity to explore the ideas and I’m deeply grateful to Hester Oberman, Anna Dornhaus, and the other participants for sharing their insights.  Sarah Bengston has written up our latest discussion (  That conversation heavily influenced my thoughts below.

I’ve been trying to identify the key areas of difference that separate people over issues of agency, free will, and determinism.  The more we discuss these matters, the more apparent it becomes:  we use the words in different ways.  Despite attempts to standardize language, our underlying conceptual structures (paradigms, meta-narratives, idols of the theater, cosms, what have you) remain different.  This post is an attempt to identify one of the principle assumptions we share – or don’t – about the world.

Does the universe branch as time passes?

If you imagine a boat flowing down a river, it can only take one path from source to sea.  Many paths may exist, but in a single passage downstream, only one path may be followed.  Let us say the current is irresistible and there is no turning back.  This strikes me as a good analogy for the physical universe, which because of entropy, must past from past to future at all times.  To the best of our knowledge, we may not pass backwards in time, but go inexorably from Big Bang to Heat Death.  The question at hand is whether that river branches or not.

It is entirely possible that we float in a canal, running straight and undeterred from beginning to end.  Many determinists believe this to be the case.  Fewer, perhaps, than a couple centuries ago.  Still.  Many people feel the universe to be a clockwork mechanism.  If we could rewind time, if we could pull the boat out of the water and put it back in farther upstream, we would eventually find ourselves back in the same place we now inhabit.  The river flows in a straight line; the cogs turn in the same way.

It is also possible that we inhabit a delta, with streams of events constantly branching and re-branching according to contingent event.  Assume for the moment that the boat cannot be steered from inside.  Even so, the current, the rocks, the shoals, even the wind may push the boat down one channel or the other.  If you removed the boat and put it back in upstream, it might end up miles away from the original path.

Unfortunately, from an empirical standpoint – judging only by the evidence of our senses – we cannot tell whether we are in a canal or a delta.  From our standpoint in the boat, the river appears to diverge.  We can see other paths, but, being unable to travel down more than one, we cannot prove (beyond doubt) that the other paths are not illusions.

In my analogy, the entire universe remains with the boat, so no physical observations can extend down those other streams.  We can imagine, but cannot realize or prove other chains of causality.  A large part of the determinism question – I think – rests on this difference of opinion.  Could things have happened otherwise?  Is our future fixed, or might it be one of many possibilities.  Other issues exist, certainly, but I think this one is the most fundamental

Philosophers may recognize this in the endless debates over existence in potentio.  When we say something potentially exists, we face a question of existence (ontology) and another of knowledge (epistemology).  The question of existence asks whether multiple possible futures exist, or whether only one future exists alongside figments of our imagination.  The question of knowledge has to do with how accurately we can see futures in both cases.

A future can, in some sense, only be imagined.  Only the present (and past) can be observed.  We can empirically verify the future only when we reach it.

You pass countless doors in your daily life.  You assume that something familiar lies behind them – a room or a stair or an exit.  It’s possible, however, that they are fake doors that lead nowhere.  The question of a branching universe is exactly this question.  What do we make of doors that have not been opened?

“Two roads diverged in a yellow wood, and sorry I could not travel both and be one traveler…”  -Robert Frost





  1. […] second category of faculties includes agency (the ability to have done otherwise), will or choice (deciding between options), moral reasoning […]

  2. […] claim that liberty is a human right without thinking humans choose effectively, that they have non-deterministic agency. The book Brave New World deals with this well in proposing humans engineered to enjoy their […]

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