In quantum mechanics, the Schrödinger equation, which describes the continuous time evolution of a system's wave function, is deterministic. However, the relationship between a system's wave function and the observable properties of the system appears to be non-deterministic.
The systems studied in chaos theory are deterministic. If the initial state were known exactly, then the future state of such a system could be predicted. However, in practice, knowledge about the future state is limited by the precision with which the initial state can be measured.
My question is, if Heisenberg uncertainty is not only a deficit based on limitations in our measurement apparati, but is also inherent to any observed quantum state, then is there any means by which "the initial state" could be "known exactly"? If not, then the determinism of chaotic systems is still only promissory, as I complained in an another post recently. The larger point that I (think I) want make (as indicated in the same prior post) is this:
If determinism is simply the doctrine that for any state S that occurs, S has an antecedent cause C sufficient to explain S, then I suppose "indeterminism" about the rational will is 'deterministic' in so far as it is the will W which is a mode of C to explain any S that arises from the action of an agent A suitable for W. But that seems to be argument by definition, not by demonstration. In other words, if the choice is between a denial of causality per se and determinism, then I affirm determinism. The issue, however, is not about causality, but about mechanism and teleology. And teleology seems to be an irreducible category of rational action not sufficiently explained by mechanistic descriptions. If "determinism" is rigged to include rational agent causation, then determinism enjoys a merely Pyrrhic victory. For by including rational agency under the head of determinism, the determinist would grant that rational agency is a legitimate form of causation. But that would be a very perverse form of determinism, historically speaking.
A further worry I have––and I use "worry" in the philosopher's sense of "an abiding academic quandry"––is how determinism is supposéd to be empirically grounded (about which I worried in the previous post cited). If a major part of the basis for determinism is the success of practical prediction, then the theoretic success of determinism rests in large part on its adequacy in prediction. (I dealt with this worry to some extent in a previous post about baseball.) If, however, prediction itself collapses at certain points, whether because of our cognitive impairments or because of inherent limitations in what is physically observable, then determinism is beset with the same faults. Meanwhile, indeterminism with respect to the deliberative will W of a rational agent A faces no parallel limitation, since the theoretical adequacy of teleological accounts of behavior maintain their value even when perfect prediction fails.
Along these lines, a commenter recently suggested that determinism, while perhaps not demonstrable––though I would go farther and say it is in principle not even utterable––, is still a good "theory" for us in order to navigate our existence in the world. The commenter likened determinism to a perfect circle: while both a circle and determinism can be defined, neither ever perfectly shows up in nature. While it might suffice to note how devastating such a concession is for determinism––namely, that the world is never perfectly deterministic!–– I would like to add two further objections.
First, positing determinism as a formal guide is exactly the worst move a determinist could make, since formal systems, of which I think the definition of geometric shapes (like a circle) is one, are, after the discovery of Gödel's incompleteness theorems, fundamentally indeterminate, or at least permanently incomplete (which is just to repeat the concession that got me to this first objection). If determinism is a formal principle, sort of like a perfect Platonic notion of Seamless Causality, and if such formal principles are not actually instantiated in the empirical world, then determinism is no more a feature of the "real world" than is a perfect circle. Both are pure abstractions, not empirically determinate realities. In addition, the very 'supernaturalness' of such formal entities suggests that Determinism qua Seamless Causality manifests cognitive access to a world beyond empirical reality, namely, the world of immaterial abstraction. Significantly, it is the traditional position of "free will" indeterminists that free will basically resides in our natural power of immaterial abstraction. In so far as intellection––i.e. the cognition of abstract reality––is in principle incommensurate with any material organ, our grasp of determinism as a formal but not empirical truth would itself ground our ability as non-deterministic agents. For if determinism is just a formal set of axioms for analyzing phenomena, then it is Gödel-indeterminate, which of course patently undermines determinism.
Second, I deny that determinism is a superior "working theory" of action, since, as I have already noted, teleological (i.e. agent-based) accounts of change are integral to human existence, and in a way that determinism cannot afford. As Professor Sandra LaFave notes in her online article about free will and determinism:
"The notion of mechanical causality applies to things but not to persons. When we account for the behavior of persons, we must use teleological explanations. …
Most philosophers nowadays acknowledge the necessity of teleological explanations of human behavior. One standard argument for teleological explanation comes from Kant.
Kant says persons are like things in the sense that physical laws apply to their bodies; the indeterminist might even admit that psychological “laws” govern some of people's consciousness events. But persons are NOT like things because they can be conscious of the operation of these laws. (A thing is just subject to laws; it is not conscious of being subject to laws.) Even the hard determinist must admit this odd characteristic of persons. People can thus be aware of physical and psychological laws as observers, from the outside.These laws are viewed as things that can operate on me, but there is always a sense in which I view myself as apart from them — for example, right now, when I am reflecting about them.
When I think about how to behave, I consider reasons. I never think about causes, because insofar as I am an agent, they are never relevant. I have to make choices, and I choose on the basis of reasons. In other words, the model of physical causation does not fit at all when you try to apply it to human choices. Even if all human choices were determined, the HD [i.e. hard-determinist] model would still be completely inadequate to describe the perspective of the agent, which is what really matters for morality. The HD position is simply at odds with human experience because it continually asserts that as far as human experience is concerned, things are not what they seem.
I should add that LaFave, in the latter paragraph, is not saying that determinism is wrong because it is counter-intuitive, or because it flies in the face of "everyday experience". If that were all we needed to refute someone, Einstein would be a madman, not a genius. Rather, LaFave's objection cuts much deeper, because she says HD does not account for all the data (as scientists like to say). Here's a syllogism, reminiscent of my recent syllogistic disproof of the claim that Darwinian natural selection explains human nature (cf. infra), to capture LaFave's worry:
1. Human action is an irreducible metaphysical category in the real world.1a. If not, the action of human advocates of determinism is an accidental metaphysical category and not a genuine feature of real-world cognition. In other words, the noises determinists make aboue the truth of determinism is as superficial to a rational grasp of the world as their burps are.
2. Human action is meaningful only in teleogical terms.2a. Even if we speak only of desires, we still must speak of them as more than bare causal states, to speak nothing of indeterminately complex desire-matrices.
2b. If perceptual desires are reducible to and identical with "bare causal states", then even falling rocks and rising flames 'desire'––which would be an astounding concession for the determinist to make to Aristotle after all these centuries!
3. Determinism does not have any theoretical 'space' for teleological action: it excludes teleogical agent-causation.
4. Therefore, determinism does not provide a metaphysically satisfactory account of the world, which of course includes der menschliche Umwelt of perceptual reasoning.
5. Therefore, determinism is false in the real world.
The point is that even if we espoused determinism merely as a "working theory", or as a "functional model", of the otherwise 'unknowable' world, it would not suffice as a working theory of what we encounter all the time, namely, our own rational agency as an irreducible category of making sense of our own existence. Indeterminism is therefore superior to determinism even in merely pragmatic terms.
In any event, another worry I have is why, on determinism, specific cases of action could not be subsumed to vintage scientific laws themselves. For if every instance of a falling apple 'perfectly' manifests (though, of course, it is hardly formally perfect), then why could not an instance of my choosing to buy one book rather than another be an instance of a natural law in its own right? Presumably, if in an otherwise gravity-free universe––a universe occupied by only one microscopic object––an apple were introduced near that molecule for an hour, the universe would, for one hour, 'have' the law of gravity. Interestingly, in the entire history of that cosmos, the law of gravity would have applied only for an hour. It would be a transient, particular event, not an overarching principle of natural action.
Presumably, as well, "the laws of physics as we know them" (how's that for a pleonasm!) did not hold prior to a certain point (i.e. the Planck epoch) in the inflation of the primeval cosmos. Did, then, other laws hold, or no laws at all? If they were laws of nature, it seems odd that they could simply fail to hold, and after a mere few nanoseconds, to boot. If they were not abiding laws of nature, however, then the cosmos began and was inflated by no knowable laws. As such, the cosmos could not be accounted for by reference to its own immanent laws, but would indicate the radical contingency of the universe. Further, if the primal conditions were only "transiently nomic", why do we presume our cosmos operates under "laws" now? Whether they last a couple nanoseconds or a few billion years, if laws of nature are incidental to the actual operation of nature, then why call them laws of nature?
The upshot as far as rational agency is concerned is that, if we can stipulate laws that apply to something as mercurial, inscrutable, unrepeatable, and transient as the birth of the cosmos, could we not also stipulate laws of action, which, while not 'violating' other principles of natural generation, included as their truthmakers the immanent action of the very agent being described by physical law? If a law could apply in the cosmos for an hour, or even just for a few nanoseconds, and then be 'sublimated' by passage into a different state of affairs (SoA), subject to distinct causal parameters, then presumably a law could exist at the junction of an agent A's deliberative choice A(c) and other laws which grounds the means for A(c).