The Road with no Branches argument

From: Immortalist (Reanimater_2000_at_yahoo.com)
Date: 10/22/04 

Date: Thu, 21 Oct 2004 22:58:22 -0700

Whenever we make a choice we are doing (or think we are doing) something like
what a traveler does when faced with a choice between different roads. The only
roads the traveler is able to choose are roads which are a continuation of the
road he is already on. By analogy, the only choices we are able to make are
choices which are a continuation of the actual past and consistent with the laws
of nature. If determinism is false, then making choices really is like this: one
“road” (the past) behind us, two or more different “roads” (future actions
consistent with the laws) in front of us. But if determinism is true, then our
journey through life is like traveling (in one direction only) on a road which
has no branches. There are other roads, leading to other destinations; if we
could get to one of these other roads, we could reach a different destination.
But we can't get to any of these other roads from the road we are actually on. So
if determinism is true, our actual future is our only possible future; we can
never choose or do anything other than what we actually do.

This is a powerful intuition pump, since it's natural to think of our future as
being “open” in the branching way suggested by the road analogy and to associate
this kind of branching structure with freedom of choice. But several crucial
assumptions have been smuggled into this picture: assumptions about time and
causation and assumptions about possibility. The assumptions about time and
causation needed to make the analogy work seem to include the following: that we
“move” through time in something like the way that we move down a road, that our
“movement” is necessarily in one direction only, from past to future, that the
past is necessarily “fixed” or beyond our control in some way that the future is
not. These assumptions are all controversial; on some theories of time and
causation (the 4D theory of time, a theory of causation that permits time travel
and backwards causation), they are all false (Lewis 1976, Horwich 1987, Sider
2001).

The assumption about possibility is that possible worlds are concrete
spatiotemporal things (in the way that roads are) and that worlds can overlap
(literally share a common part) in the way that roads can overlap. But most
possible worlds theorists reject both assumptions and nearly everyone rejects the
second assumption (Adams 1974, Lewis 1986).

Determinism (without these additional assumptions) does not imply that our
“journey” through life is like moving down a road; the contrast between
determinism and non-determinism is not the contrast between traveling on a
branching road and traveling on a road with no branches.

If this intuition pump nevertheless continues to engage us, it is because we
think that our range of possible choices is constrained by two factors: the laws
and the past. We can't change or break the laws; we cannot causally affect the
past. (Even if backwards causation is logically possible, it is not within our
power.) These two premises are the basis of the best known contemporary argument
for incompatibilism: the Consequence argument. More of this later.

http://plato.stanford.edu/entries/incompatibilism-arguments/
http://www.campusprogram.com/reference/en/wikipedia/e/el/elbow_room.html
http://actiontheory.free.fr/Actionpuzzles.htm

Relevant Pages

  • Re: The Road with no Branches argument
    ... > what a traveler does when faced with a choice between different roads. ... > journey through life is like traveling on a road which ... > this kind of branching structure with freedom of choice. ... > causation and assumptions about possibility. ...
    (sci.logic)
  • Re: The Road with no Branches argument
    ... > what a traveler does when faced with a choice between different roads. ... If determinism is false, then making choices really is like ... > consistent with the laws) in front of us. ... > journey through life is like traveling on a road ...
    (sci.logic)
  • Re: So Many Road to Travel
    ... the traveling of many ... >>>different roads require the wearing of many ... >>>different hats so.. ... Mother Machree ...
    (soc.culture.irish)