|Okay, let me go back to Post 9 in which Cal stated: |
This is no a priori "must", it is an observed fact that the behavior of particles follows those statistical probabilities. If a physicist says that a particle "must" do this or that under those circumstances, he means that empirical evidence has shown that particles invariably behave in that manner, and not that there is some philosophical principle that makes such behavior necessary. If all the physicist means when he says that a particle (or any other physical entity) "must" do this or that under those circumstances is that empirical evidence has shown that particles invariably behave in that manner, then he is not saying precisely what he means, because to say that something "must" act a certain way under certain conditions is not simply to say that it has (in the past) invariably behaved that way; rather, it is to say that it will, under the same conditions, behave that way in the future. That is precisely what a "law" of nature is; it tells us not how a thing has invariably behaved, but how it will or must behave under relevantly similar circumstances. The law that a free falling body accelerates at the rate of 10 meters per second squared is not simply a statement that free falling bodies have invariably behaved that way; it is a statement that they must (qua free falling bodies) behave that way in the future.
Hume has famously arguing that just because something behaved a certain way in the past is no indication that it will behave that way in the future. All we can ascertain from empirical observation, he held, is that things did behave a certain way; we cannot, on the strength of empirical observation alone, say that they will behave that way in the future, even if we assume that all of the relevant circumstances are identical. That, he argued, would be going beyond empirical observation into the realm of rational speculation, for which we have no empirical justification. In fact, said Hume, we can't even say that things will probably behave a certain way, because even probabilities are based on the inference that we have some reason for believing not just that they've behaved that way in the past, but that they will probably do so in the future, which empirical observation cannot by itself provide. If, for example, a meteorologist forecasts a 90% chance of rain, his forecast is based not simply on the empirical observation of a low pressure front moving into the area, but also on the principle that similar causes (low air pressure) will have similar effects (a greater likelihood of rain). But, according to Hume, all that empirical evidence can tell us is that certain events did occur. It cannot tell us that they will occur or are even likely to do so. Whereas we can reason from the general to the particular - from how something behaves in all cases to how it will behave in some cases, we cannot, he argued, reason from the particular to the general - from how something behaves in some cases to how it will behave in all cases. For example, we can infer from the generalization that free falling bodies accelerate at the rate of 10 meters per second squared that this free falling body in particular will accelerate at that rate. But we cannot infer from the fact that this free falling body accelerated at the rate of 10 meters per second squared, that all free falling bodies will do so.
Fortunately, Objectivism provides the perfect counter to Hume in terms of the law of identity. Because a thing's identity just is its attributes (since there is no "substratum" underlying and uniting them), if a thing has the attribute of behaving a certain way under certain conditions, then it will possess that attribute whenever it exists under those conditions, and accordingly, we can infer how it will behave in the future, given a recurrence of those conditions. Not that Rand is the first philosopher to have identified this principle as the basis of induction. Aristotelian logician H.W.B. Joseph did so, in his insightful book, An Introduction to Logic (1906).
So, when you say,
Such philosophical principles are ultimately derived from empirical evidence, you are only half right, because without a recognition of the relevance of the law of identity and of the fact that the same thing must possess the same attributes under the same conditions, empirical evidence does not enable us to reason from the particular to the general. Similarly, when you say
and it is empirical evidence that has shown that principles that work for macroscopic systems do not work for subatomic systems, you are ignoring the fact that it is not simply empirical evidence that justifies macroscopic principles, but rather empirical evidence along with the principle of induction, which is itself based on the principle of identity.
In Post 15, I wrote, "To be is to possess identity, and a thing's identity just is its attributes (which include its behavior). Under certain conditions, a certain entity will possess certain attributes. If, under the same conditions, it does not possess those attributes, then it is not the same thing. This is an indispensable principle of all reasoning. Cal replied,
Why? This statement is so vague that it becomes meaningless. Even in the macroscopic world things change, even under the same circumstances, and with them some attributes will change too. Yes, things change, but their changing is itself an action that takes place under a given set of conditions. The law of identity states that if you reproduce those conditions exactly, including the condition of the entity itself, then you will have the same action. For example, the flowered plant on my desk is gradually changing, the flowers in various stages of growth and decay, so the plant's action today is different from its action yesterday, even though its external environment is essentially the same, but if we were to reproduce the conditions in which it existed yesterday, including its stage of development at that time, then it would take the same action.
A snowflake will melt and an egg will hatch (or start to rot, depending on the circumstances). You may try to circumvent this by extending the "circumstances" to the complete internal state of the entity, but that would imply that the entity after a fraction of a second is no longer the same entity, which seems to me hardly a satisfactory solution. I'm using "same entity" to mean exactly the same, with exactly the same attributes. So what I am saying is that given exactly the same causes (i.e., exactly the same entity and conditions), the same effects must ensue. That's the underlying premise that makes causal generalization possible and in the absence of which, it is impossible.
One of the attributes of subatomic particles is their random behavior..., which you’ll always observe. Random behavior is not, strictly speaking, an attribute of the object; it is an attribute of the object's appearance. The object appears to behave randomly, which simply reflects our incomplete knowledge of the entity and its conditions. For example: "Watch the movements of a waterfall, how it breaks into a thousand parts which seem to shift and hang, and pause and hurry, first one, and then another, so that the whole never presents quite the same face twice; yet there is not a particle of water whose path is not absolutely determined by the forces acting on it in accordance with quite simple mechanical laws. No one would suppose that because these mechanical laws are unchanging, the waterfall must wear a monotonous and unchanging face; and so it is, on a larger scale, with the course of nature. Nature is uniform in the sense that under like conditions like events occur..." (Joseph, An Introduction to Logic, p. 402)
I wrote, "If I own a red Toyota, which is parked in my driveway, and next morning find a black Ferrari parked there, it is not rational for me to infer that it is the same car, albeit with different attributes." Cal replied,
Does that in any way contradict my argument? The only point I was making is that an entity is its attributes. If you agree with this, then we are one step closer to agreement on the broader issue. I wrote, "To reply that this refers to macroscopic entities is to miss the point, which is that even macroscopic principles are impossible without the underlying presupposition of causal necessity." Cal replied,
This sentence doesn't make sense to me. Of course the point is that your example is a macroscopic example and of course in the macroscopic world the classical causality holds, that was exactly my point. For many centuries this has seemed to be the only possibility while all the evidence always has confirmed this principle, and that is the reason that we've come to see it as an absolute principle. However, when we were able to study subatomic particles, we discovered that in that domain this principle no longer applies; the fact that it has worked so long and so well for us is no reason to extrapolate it to the subatomic realm if the experimental evidence tells us differently, it was time to check our premises. But the "experimental evidence" doesn't tell us differently. Evidence has to be interpreted in accordance with an underlying principle of induction in order to have any meaning at all. But it is that very principle of induction that is incompatible with metaphysical randomness. The action of the ball on a roulette wheel is random to the casual observer, because he is not privy to all of the forces acting on it, but in reality its action is governed by strict causality. It is no different for subatomic particles, however random their behavior appears to the observer. Like probability, randomness is epistemological, not metaphysical.