Monday, May 21, 2007

STR and the Metaphysics of Time

The Special Theory of Relativity (STR) is one of the most well-confirmed theories in modern physics, or so I've been told by those I trust. It's also widely regarded by metaphysicians as being of utmost significance for the metaphysics of time. In particular, it's widely thought to have dealt a death blow to the tensed (A-theory) of time. The reason is that all versions of the A-theory of time require the postulation of an absolute, objective 'now', whereas STR only acknowledges simultaneity relative to an inertial reference frame. I say that STR doesn't 'acknowledge' absolute simultaneity here because I think that's the accurate way to put it, but many would endorse the stronger claim that STR positively rules out any such thing as an absolute, objective 'now'.

In a paper written about three decades ago, Hilary Putnam famously declared that STR had decisively settled the metaphysical debate between the A-theory and the tenseless (B-theory) of time in favor of the latter. More recently, in his 2001 book Four-Dimensionalism, Ted Sider has argued that the A-theory requires an objectionable 'scientific revisionism' regarding STR and is therefore to be rejected. Similar sentiments from B-theorists like Putnam and Sider can easily be multiplied. Furthermore, many major proponents of the A-theory like Dean Zimmerman admit that objections based on STR have kept them awake at night (Dean makes this admission in his contribution to a forthcoming book on debated questions in metaphysics).

I beg to differ with such sentiments. As I see it, few if any major metaphysical questions have been settled by advancements in science. The reason is that major metaphysical questions address issues at a deeper level than sciences like physics and biology are equipped to handle. In particular, I don't think that STR has any significance for the debate between tensed and tenseless theories of time. Pace Sider, I claim that A-theorists can embrace STR without any objectionable revisionism.

Here's how I see matters. Like Newton before him and like many others since, Einstein assumed that the 't' variable in his equations denoted time - not just time as it can it principle be measured by observers like us (empirical time), but time itself (metaphysical time). Newton had no particular need to distinguish between the two, though he certainly could have had he wanted to. Einstein, however, defines 'simultaneity' in broadly epistemic terms (recall his famous thought-experiment on how two observers, one on a swiftly moving train, the other standing beside the train tracks, would ascertain the timing of a lightning-strike at the front of the train). Given the fact that epistemological and metaphysical questions are distinct, Einstein therefore had a good reason for distinguishing empirical time from metaphysical time. But he didn't. He wrote as if his equations had metaphysical, and not just empirical, significance. And countless scientists and philosophers have just gone along with him in that. But why should anyone who appreciates the epistemology/metaphysics distinction grant STR such metaphysical significance? Why can't the A-theorist simply say that STR gives us an accurate description of empirical time but says nothing about the metaphysical time with which the A-theory is concerned? As far as I can see, that's a wholly respectable position to take. In philosophy of science terms, it amounts to opting for an instrumentalist, as opposed to a realist, interpretation of STR, at least as far as its references to 'time' are concerned.

One reason for thinking that this is the right approach to take is that the finite speed of light seems to be a metaphysically contingent fact. It is easy to imagine light, or some other type of signal, going faster and faster until, in the limit, transmission is instantaneous, in which case even on Einstein's verificationist epistemological criteria, we'd have to admit absolute simultaneity. Now how do we know that no such instantaneous signals exist? The only reason for thinking that they don't would have to be that if such signals did exist, then they ought to be detectable by us, but they aren't, etc. But why accept that? Why think that the limitations of our finite minds define the limits of reality? Furthermore, it seems at least possible that a being like God, one who is simultaneously present to and aware of the entire universe, exists. If so, then such a being's God's-eye view would provide a privileged reference frame that could be identified with the absolute, objective 'now' of a tensed metaphysical time. Of course, that reference frame wouldn't be of any use to physicists, but so what? Why should we expect specialists on matters physical to have anything particularly important to say about matters meta-physical? (Those who endorse scientific materialism - the view that the physical world is all there is - might suppose we have a reason for expecting this, but scientific materialism is a metaphysical thesis, not one that can itself be established by the deliverances of physics.)

Friday, May 11, 2007

Are There 'De Re' and 'De Dicto' Beliefs?

'Maverick Philosopher' Bill Vallicella has written recently on the distinction between 'de re' and 'de dicto' beliefs. As he explains the distinction, a de dicto belief is a belief about a dictum (basically, a proposition). Thus, in "Sam believes that Cicero is a politician" the verb "believes" is followed by a 'that'-clause which expresses a proposition about Cicero (that he is a politician). A de re belief, on the other hand, is supposed to take as its primary object a res (or individual thing). Thus, in "Cicero is believed by Sam to be a politician" the verb "believes" takes Cicero himself as its grammatical object, not a 'that'-clause.

For more on the de re / de dicto distinction, see here.

Now, what's not immediately clear is what this distinction is supposed to amount to. Why aren't "Cicero is believed by Sam to be a politician" and "Sam believes that Cicero is a politician" synonymous? Well, the reason for differentiating between them has to do with the fact that this inference
  1. Sam believes that Cicero is a politician.
  2. Cicero = Tully.
  3. Sam believes that Tully is a politician.
looks invalid, whereas this inference
  1. Cicero is believed by Sam to be a politician.
  2. Cicero = Tully.
  3. Tully is believed by Sam to be a politician.
looks valid.

What I'd like to suggest, however, is that the difference between the two arguments doesn't really have to do with a distinction between two kinds of belief, de dicto and de re, but with whether we take an internal or an external standpoint on the sense of the name 'Cicero'. In other words, is the meaning of 'Cicero' to be evaluated from the perspective of the one to whom the belief is attributed (in this case Sam) or from the perspective of the person doing the attibuting?

Let's start with the internal perspective (Sam's). It is natural to suppose that, in believing that Cicero is a politician, Sam associates some descriptive content (a 'sense') with the name ‘Cicero’. (If 'Cicero' had no such content for Sam, then the name would be nothing but a placeholder for a 'something I know not what', in which case it's hard to see how Sam could be in a position to believe that that is a politician.) Suppose that the sense that Sam associates with ‘Cicero’ is simply ‘the author of this book’. In that case what Sam believes is that the author of this book is a politician. If, in addition, the name ‘Tully’ carries the same sense for Sam, then we can swap the two names without alteration of meaning. So this inference would be valid:
  1. Sam believes that Cicero (as Sam conceives of him) is a philosopher.
  2. Cicero = Tully (as Sam conceives of them)
  3. Sam believes that Tully (as Sam conceives of him) is a philosopher.
But, if we do not suppose that the two names carry the same sense for Sam then, even though we know that Cicero = Tully, the inference would be invalid:
  1. Sam believes that Cicero (as Sam conceives of him) is a philosopher.
  2. Cicero = Tully (as we conceive of them)
  3. Sam believes that Tully (as Sam conceives of him) is a philosopher.
The two preceding inferences concern only what are commonly called 'de dicto beliefs’, but notice that what explains the difference in validity has nothing whatsoever to do with whether the beliefs in question are de dicto or de re, and everything to do with whether we evaluate the semantic value of 'Cicero' and 'Tully' from Sam's (internal) perspective or from our (external) perspective.

What are commonly called ‘de re beliefs’ involve us assuming an external standpoint in which we pretend that we know something that the believer may not. Thus, we know that what Sam conceives of simply as ‘the author of this book’ is in fact Cicero. Furthermore, we know that Cicero = Tully. Hence, from our vantage point, we can validly reason as follows:
  1. Sam believes that Cicero (as we conceive of him) is a philosopher.
  2. Cicero = Tully (as we conceive of them)
  3. Sam believes that Tully (as we conceive of him) is a philosopher.
From a purely external perspective, Sam’s conception of Cicero is irrelevant. Hence we can safely suppose here (if we want to) that Sam’s conception of Cicero is a bare, contentless ‘that’, a name that refers but not via any senses. But we haven't really eliminated senses from the name. Rather, we have just substituted our sense for Sam's.

So, the difference between "Cicero is believed by Sam to be a politician" and "Sam believes that Cicero is a politician" amounts to nothing more than this: By placing a name ('Cicero') in the initial position, as opposed to inside an attitudinal 'that'-clause, we signal that the denotation of the name is to be assessed from an external vantage point. If, on the other hand, we place a name inside an attitudinal 'that'-clause, we signal that the denotation of the name is to be determined from an internal vantage point. There's nothing more to the de re / de dicto distinction that I can see.

Monday, May 07, 2007

Four Difficulties for Materialism

Here's a nice short piece by Frank Pastore. It's entitled "Why Atheism Fails: The Four Big Bangs". The four problems, posed somewhat more precisely than Pastore himself does, are:
  • How did the universe come about given that it's non-eternal?
  • How could life have emerged from non-living matter?
  • How could mind and self-consciousness have emerged from matter?
  • How could there be objective good and evil if materialism is true?
Though Pastore doesn't develop any of these questions in much detail, these are all good questions. And materialists have yet to spell out convincing answers to them. Indeed, it is quite unclear that they can do so within the constraints of their metaphysics. Of course, some materialists will simply deny the presuppositions of the questions. Some, for example, will deny the existence of objective good and evil. Others will deny the existence of self-conscious minds. Others will insist on the eternity of the physical universe (or of some sort of physical meta-verse). The first two moves carry a heavy burden because of their radical departure from common sense. The last one is sheer speculation. Whether there is a physical meta-verse is not something that any conceivable empirical data is going to be able to confirm.

Pastore does fall into the common conflation of atheism and materialism. Technically speaking, one can be an atheist without being a materialist. (The converse is not true, however, since no standard account of God allows God to be a material being.) Pastore's conflation is understandable, however, because a great many (if not most) atheists are materialists.

PS. Some of the comments on Pastore's article are amusing, but I wouldn't put much stock in most of them. Anyone who thinks these problems are easily and painlessly solved by materialists has at best a superficial understanding of the difficulties. Likewise, anyone who thinks that a non-materialist worldview like theism doesn't face some difficult problems needs to read up on some of the standard objections.

Friday, May 04, 2007

Free Will Theism + Presentism = Open Theism

Suppose that free will theism is true.

Free will theism entails theism, the thesis that God exists, where 'God' is understood to denote a necessary being essentially possessing the greatest possible set of compossible great-making properties, including maximal power, knowledge, and goodness.

Free will theism also entails that God has created a world of creatures some of which are free in the 'libertarian' sense. Libertarian freedom is incompatible with determinism and thus implies that the future is 'causally open' with respect to creaturely free choices. In other words, there are 'future contingents'.

Suppose further that presentism is true. Presentism is the thesis that whatever exists, exists now, in the present.

Grant both of those theses (free will theism and presentism), along with two additional widely accepted notions - the correspondence theory of truth and the causal dependency of later states on earlier states - and one gets a straightforward argument for open theism, a species of free will theism that holds that the future is epistemically open for God in precisely those respects in which it is causally open.

Here's the argument:
  1. God’s knowledge corresponds to what is true. (divine omniscience)
  2. What is true corresponds to what is real. (correspondence theory of truth)
  3. God’s knowledge corresponds to what is real. (from 1 and 2)
  4. What is real corresponds to what is present. (presentism)
  5. God’s knowledge corresponds to what is present. (from 3 and 4)
  6. What is future stands to what is present as an effect does to its cause. (time order of causal dependency)
  7. The future is epistemically settled for God iff the future is fully ‘present in its causes’. (from 5 and 6)
  8. The future is not fully present in its causes. (future contingency)
  9. The future is not epistemically settled for God. (from 7 and 8)