Read the words again: "only one possible [X]" means necessarily one X.
Let us define determinism (D) as the doctrine that
at time t there is only one possible configuration of the world (C:W) after t (C:Wt+). Everything at time tC:W is a direct and necessary result of the C:W at t.
Tonight I smelled a difficulty in this notion, which I want to address briefly. I need more time to ponder it in depth.
If we accept D, as defined above, we deny it is possible for C:W at t to result in anything other than C:Wt+. The problem I detect is twofold, however.
First, if D is true, then necessitarianism is true, and necessity exhausts modality, which makes possibility a vacuous notion (and an unreality). As such, D should be restated as D*, namely,
at time t there is only one configuration of the world (C:W) at any time other than t (C:Wt*).
Notice the absence of both the word "possible" and the removal of any sense of futurity.
Second, what is the ontological status of the future in D? If C:Wt+ is not yet actual, then D* entails that C:W necessarily results in a non-actual (i.e. merely potential) state of affairs (SOA). As such, C:W necessarily entails complete potentiality, in which case D is false. The future does not yet exist, and therefore does not really exist, which means D can only posit a world that engenders nonexistent SOAs, if it engenders anything at all.
Now, if the reply is to grant the existence of the future as an eternal dimension of the 4D spacetime manifold (á la Minkowski space), then we raise enormous questions about how valid it is to say geometric models literally embody the world. "The map is not the territory," as Korzybski would have it. Geometry may be useful for making sense of broad swaths of data, but that does not mean the geometry is really "the way the world is." After all, Euclidean geometry and Newtonian mechanics are still valid in most contexts, but that does not mean we (should) believe they truly, literally, indexically manifest "the way the world is." So it is with Minkowskian geometry: useful in practice, provisional in reality.
Thus, once again we are thrown back to the radical freedom of the explorer, even in his acts of "scientifically demonstrating" the truth of D. It is up to him (!) which 'dialect' of geometry he will use, what standards of rational warrant to which he will hold himself, which data he will favor or ignore, and so on. If such exploration is not really up to him, but is instead a blind clutching at the only paths he can cognitively tread, then either his (scientific) rationality is a sham (cf. e.g. this abstract) or it is but a tiny rivulet of the cosmos' total active consciousness, both conclusions which seriously undermine materialist scientism.
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On a different front, I realized today I want to make it a habit to use the following expression, "Ours is a world which is currently described by most scientists as x, y, and z." A mouthful I know, but the more compact, more 'obvious' locution is just a bumper sticker for scientism: "Science proves the world is x, y, and z."
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Another thought I had, modus tollens: if humans are determined by what they perceive, but if perception is indeterminate, then humans are not psychologically determined.
I ask you to give me the value of √-2. You say…?
I ask you to describe the angles and dimensions of a Necker cube.
You tell me…?
I ask you to identify the highest staircase in an Escher house.
You tell me…?
In each case, what you sense does not, in principle, determine how you perceive it. Indeed, all perception is transcendentally rational. Therefore, perception––stimuli––cannot simply determine your behavior. You are a generative locus of perceptual uniqueness. You are free.
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Have been brainstorming about my lecture this Sunday. I have been asked to answer the question, "Do humans have freewill?"
There are two ways to answer this question (in the affirmative).
First, assuming that freewill is incompatible with determinism, show that determinism is false and therefore freewill abides by default. In other words, if determinism were true, our experience could not be what it is, but our experience is manifestly what it is, therefore determinism is false. This is, I gather, Van Inwagen's approach in An Essay on Free Will, a copy of which I hope to have by next week.
Second, take stock of broad, consistent features of human behavior and then see if they are coherent without freewill. If not, then freewill follows as manifestly as the features of human consciousness by which it functions. Determinism would be a function of freewill, as the proof for determinism would be among the other dimensions, or fruits, of free human consciousness.