On miracles
Just a quick sketch of an argument against thinking of miracles as violations of laws of nature. I doubt it's very original (In fact, I know it isn't, because Geoff Anders was talking about something like this a while back), and I'm sure it's fairly naïve. But anyhow, into the breach.
First, I'm concerned with official laws of nature, rather than statistical laws. Official laws say what happens, categorically: all ravens are black; momentum is conserved; the evolution of the quantum wave-function obeys such-and-such a differential equation—that kind of thing.
(Statistical laws, on the other hand, say that certain things are more likely than others to occur, in whatever sense of "likely" is appropriate here. It's hard to say what precisely constitutes a "violation" of a statistical law, but at least on some readings miracles certainly do violate some statistical laws, simply by virtue of being unusual events. But the unusual, in various degrees, is really pretty commonplace.)
Second, i'm concerned with macroscopic miracles: events at the scale of people and everyday objects. Lazarus is raised from the dead, Moses parts the Red Sea, that kind of thing. Maybe there are miracles that occur on the Planck scale, which are only detectable with sensitive instruments; but these aren't the sort of miracles that make a difference to most religions.
Then the main argument is just this: on our best accounts, the official laws of nature don't rule out any macroscopic events to speak of. (This, by the way, is also a problem for "falsifiability" accounts of scientific theories---in case that coffin needed any more nails.)
For illustration, imagine that the official laws are Newtonian mechanics. People die, sometimes; this is one of the events that is consistent with the laws (I presume). Well, it's a fact about Newtonian mechanics that if an event is consistent with it, the time-reversal of that event is consistent too. So run the death backwards, and---presto!---Lazarus rises from the dead. (Statistical laws broken? Hell yeah (in some suitable sense of "broken"). But that, remember, is none of our concern.)
The kinds of observations we ordinarily make of the world aren't nearly fine-toothed enough to distinguish states of affairs in which (according to the dynamics) run-of-the-mill events are about to occur, from states of affairs in which (still according to the dynamics) great marvels are about to occur. And so miraculous events are never physically impossible, conditionalized on our knowledge of the physical state of the world. And, I claim, this situation isn't peculiar to Newtonian mechanics. It ought to be a feature of any good candidate for the official laws (have to think more about why this would be true).
(When quantum physics enters the picture, the story is even more fun. My grip on the quantum world is loose, but as I understand the folk tales, anything is possible.)
So if macroscopic events can count as miracles (as I assume they can), then miracles aren't violations of the official laws of nature.
First, I'm concerned with official laws of nature, rather than statistical laws. Official laws say what happens, categorically: all ravens are black; momentum is conserved; the evolution of the quantum wave-function obeys such-and-such a differential equation—that kind of thing.
(Statistical laws, on the other hand, say that certain things are more likely than others to occur, in whatever sense of "likely" is appropriate here. It's hard to say what precisely constitutes a "violation" of a statistical law, but at least on some readings miracles certainly do violate some statistical laws, simply by virtue of being unusual events. But the unusual, in various degrees, is really pretty commonplace.)
Second, i'm concerned with macroscopic miracles: events at the scale of people and everyday objects. Lazarus is raised from the dead, Moses parts the Red Sea, that kind of thing. Maybe there are miracles that occur on the Planck scale, which are only detectable with sensitive instruments; but these aren't the sort of miracles that make a difference to most religions.
Then the main argument is just this: on our best accounts, the official laws of nature don't rule out any macroscopic events to speak of. (This, by the way, is also a problem for "falsifiability" accounts of scientific theories---in case that coffin needed any more nails.)
For illustration, imagine that the official laws are Newtonian mechanics. People die, sometimes; this is one of the events that is consistent with the laws (I presume). Well, it's a fact about Newtonian mechanics that if an event is consistent with it, the time-reversal of that event is consistent too. So run the death backwards, and---presto!---Lazarus rises from the dead. (Statistical laws broken? Hell yeah (in some suitable sense of "broken"). But that, remember, is none of our concern.)
The kinds of observations we ordinarily make of the world aren't nearly fine-toothed enough to distinguish states of affairs in which (according to the dynamics) run-of-the-mill events are about to occur, from states of affairs in which (still according to the dynamics) great marvels are about to occur. And so miraculous events are never physically impossible, conditionalized on our knowledge of the physical state of the world. And, I claim, this situation isn't peculiar to Newtonian mechanics. It ought to be a feature of any good candidate for the official laws (have to think more about why this would be true).
(When quantum physics enters the picture, the story is even more fun. My grip on the quantum world is loose, but as I understand the folk tales, anything is possible.)
So if macroscopic events can count as miracles (as I assume they can), then miracles aren't violations of the official laws of nature.
Posted by Jeff on Sunday, December 03, 2006
4 Comments:
Hey Jeff, I just came across your blog tonight. Interesting discussion. A thought:
Well, it's a fact about Newtonian mechanics that if an event is consistent with it, the time-reversal of that event is consistent too. So run the death backwards, and---presto!---Lazarus rises from the dead.
I'm not sure it's as simple as that. Maybe (maybe) it's consistent with Newtonian mechanics that, after Lazurus dies, the fundamental particles in the region in question follow a reverse pattern, and sometime shortly after, the world (or region) is in a state qualitatively identical to the state that previously contained a living Lazurus. But it doesn't follow from this that Lazurus is back from the dead; we have an organism that looks and behaves much like Lazurus did, but it will depend on the correct account of personal identity whether that organism is Lazurus, the guy who died. I can see some reason to think that this would be some new organism, a kind of Lazurus-duplicate.
It's also not clear that the reversal in question is even possible, given the way the particles actually were. Yes, the time reversal of an Newtonian-possible event is Newtonian-possible; that's not to say that an event, followed immediately by its reversal, is Newtonian-possible. (Consider an object falling under the force of gravity from t1 to t2. Yes, it's Newtonian-possible for an object to trace its root backwards over time -- this is what happens when I throw a ball up with the right velocity, along the same path -- but it's not possible for the ball suddenly to reverse course in midair without the action of an outside force on it; Newton's first law prohibits that.
So I think it's at least not obvious that, say, Lazurus's resurrection was or would have been Newtonian-possible.
Hi Jonathan! Glad you stopped by.
But it doesn't follow from this that Lazurus is back from the dead; we have an organism that looks and behaves much like Lazurus did, but it will depend on the correct account of personal identity whether that organism is Lazurus, the guy who died.
Point taken. I wasn't really worried about the conceptual issues involved in resurrection, just the empirical facts involved in such an event. If the right account of personal identity rules out Lazarus-type resurrection (though I can't see any compelling reason why it would), that would be a separate issue from whether a dead person turning into a living person violates natural law.
...that's not to say that an event, followed immediately by its reversal, is Newtonian-possible.
Yes, that's right. I should clarify. It probably isn't possible that Lazarus's death would be followed by an exact reversal of the same death event. (Maybe it is possible, if everything could be delicately balanced so that each particle is motionless at the time we reflect around. But that would be the weird case.) Rather, what is possible is that Lazarus's death would be followed by an event which macroscopically looks like the time reversal of the death.
Here's the idea. We know there is some physically possible event, Death, which starts in state LA (Lazarus Alive) and ends in state LD (Lazarus Dead). In fact, there are a whole bunch of them, because there are lots and lots and lots of microphysical scenarios that all look pretty much the same macroscopically. So there are also lots of events, the Resurrections, which are the time reversals of the Deaths. What is Newtonian-possible is that one of the Deaths be immediately followed by one of the Resurrections (not necessarily its own reversal).
For this to be true, all that has to hold is that one of the LD states is the time-reversal of another LD state (the state needs to build in things like instantaneous velocities of particles; so the time-reversal of a state reverses all of those vectors). It would be very surprising if this weren't true; in fact, I conjecture that the time reversals of all of the LDs are exactly the LDs again (again, not that each LD is its own reversal; but each LD is a reversal of some LD).
Does that help?
Jeff: You say "so miraculous events are never physically impossible, conditionalized on our knowledge of the physical state of the world." But what about: conditionalized on the actual physical state of the world?
I guess I let this thread slip. Probably no one is going to come back and read this anymore, but I feel like for the sake of completeness I should respond to David's comment. Also, welcome to the blog, David!
I argued that no macroscopic event is ruled out by the official laws of nature, given the macroscopic state of the world at a time. So if by "the actual physical state of the world" you mean the macroscopic physical state, then I make no amendments. On the other hand, you might have meant the microphysical state of the world. In that case, some events are ruled out---in fact, if the laws are deterministic, almost all events are ruled out. That holds for perfectly ordinary events as much as for miracles. I don't think it cuts against my position at all.
Here's how I imagine an argument going.
A: Lazarus rose from the dead!
B: Then you must think that the laws of nature have been violated.
A: Nope, this is consistent with the laws of nature: Jeff says so.
B: Well, it's inconsistent with the laws of nature given the actual microphysical state of the world at the time of Lazarus's death.
A: Why think that? We infer the microphysical state of the world from macroscopic events. One of those events is that Lazarus rose from the dead. Therefore, I suppose the microstate wasn't one of those that rules out his rising from the dead.
(They might go on:
B: But the resurrection-permitting microstates are extraordinarily unlikely!
A: That's true--this was an extraordinary event! But that doesn't mean any laws were violated. It just means that an extremely improbable microstate obtained (in some sense of improbable).
)
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