You're confusing an actuality with a possibility. Every item on the restaurant menu is a
possibility. However, the Chef Salad on the table in front of me is an
actuality. There will be only
one actuality. However, there are always
more than one possibility.
Each person to their own menu item. Each menu item that is selected is not probabilistically selected, not freely willed, but necessarily selected. It cannot happen otherwise.
The choices made "will" not happen otherwise, but they certainly "can" happen otherwise. Every item on the menu is a real possibility for every person at the table. The fact that they will not choose an item does not logically imply that they could not choose that item.
It is a simple matter of what "can" and "will" actually mean. What "will" happen is not the same as what "can" happen.
And whenever choosing happens, there will always be at least two things that "can" happen, even though there is only one thing that "will" happen.
If you select Steak and Salad, your wife selects Lasagna, your friend selects Spanish Mackerel and his wife selects Caeser Salad, four menu items are taken, each and every item selection necessitated/fixed/ determined by the mental/physical condition of the person/brain/mind involved in the process of determination.
Absolutely correct! Even though I "could" have selected the Lasagna, I didn't. And given those exact same circumstances, I never "would have" selected the Lasagna, even though I "could have".
- If Causal Determinism is true ... - Bruce Silverstein - BA Philosophy - Quora
If Bruce would like to participate in this conversation, then I'd be happy to straighten him out as well. But I see no point in trying to have a conversation with someone who isn't here to defend his position. You may prefer his rhetoric to your own, but he is not actually saying anything that you are not already saying. So, let's avoid unnecessary redundancy.
'Possibility' implies uncertainty, that something may or may not happen.
Exactly. The function of our notions of "possibility" is to deal with everyday uncertainty. When we do not know what "will" happen, we imagine what "can" happen, to prepare for what does happen.
There are no 'possibilities' in determinism.
When we are in the
context of deterministic reality, there are no possibilities. Thus, when addressing functional possibilities we shift into a different context, the context where we speak of things that "can" happen, rather than things that "will" happen. We don't know whether the traffic light
will be red or green when we get there (the deterministic reality is unknown), but we know for certain that it
could be red and it also
could be green (two real possibilities).
The function of a "possibility" is to allow us to imagine things that may or may not happen. The restaurant menu, for example, is a list of things that we might or might not choose for dinner. The function of such an imagined future is to "try it out" to see if we might want to choose it. For example, when I considered having that steak for dinner, I recalled having bacon and eggs for breakfast and a double cheeseburger for lunch, and what first looked good to me suddenly seemed less appetizing. That's how a "possibility", something that "can" happen, logically functions.
A possibility might never be selected, but it remains a possibility, something we have the "ability" to do, something that we "can" do, even if we never actually do it.
What is determined must necessarily happen as determined
Yes. And if it is "determined" (causally necessary) that I would consider the possibility of the steak, and then reject it, then that possibility, as a mental event, was causally necessary from any prior point in time and inevitably "would" happen, without deviation.
Of course, it "could" have happened differently. If I had coffee and toast for breakfast, and a salad for lunch, then the possibility of steak for dinner "would" have been very appealing, and I "would", under those circumstances, order the steak instead of the salad for dinner.
But that, of course, did not happen, even though it "could" have.
Options within a determined system are not 'possibilities' in the sense that an action may or may not happen. Options are either open or closed for someone depending on the state of the system.
An "option" is a possible choice. It is something that you "can" choose, even if you never choose it. To use the word "option" invokes the context of possibilities.
The fact that we definitely will not choose that option does not mean that we could not choose it.
Both the salad and the steak were options that were "open" to me. To be "open" simply means that I had the ability to choose it, if I wanted to.
In one scenario, where I had the bacon at breakfast and the cheeseburger at lunch, that recollection "closed" the steak option, and I chose the salad.
But the closing was done by me, due to my own reasons. Determinism did not step in and close that option for me. I did that myself. In fact, determinism simply insured that it would be me, and no one else, that would close that option.
There is, for instance, the option to become an astronaut, to fly to the Space Station, an option that is not realizable for 99.999% of the population
That's a good point. We may imagine ourselves as astronauts without it being a real possibility. That would be a fantasy for most people. A fantasy is not expected to be a real possibility.
Superman may "leap tall buildings in a single bound", but that is physically impossible for us.
A real possibility is something that we actually can do, if we choose to do it.
In a deterministic system that includes a human brain with the neurological capacity to make decisions,
that mind will always have multiple possibilities to choose from during that operation.
There are no possibilities within the brain/mind in the sense that something not determined could possibly happen.
The paradox here is created by conflating the two "senses" that we're talking about. Are we speaking in the sense of possibilities, or, are we speaking in the sense of actualities. These are two very different senses. Are we speaking of things that "can" happen, or, are we speaking of things that "will" happen.
I believe it is a mental error to confuse these two contexts. Most of the time, we use them correctly, and even closely, without confusion.
For example, "I chose the salad, even though I could have chosen the steak", is considered a true statement in both its parts.
But now the hard determinist comes along and says, "No, you never could have chosen the steak". Which makes no sense at all, because, just a moment ago, before I had made my choice, "I can choose the salad" and "I can choose the steak" were both equally true.
If "I can choose the steak" was ever true at any point in the past, then "I could have chosen the steak" will be forever true in the future, when referring to that same past. It is a simple change in the tense of the verb. It is built into the logic of our language.
So, back to your original question. What does it mean to say "something that is not determined cannot possibly happen"? It means we're confusing things.
Why? Because something that can possibly happen may or may not be determined to happen.
Events proceed as determined, no deviation,
Correct.
no possibility of doing otherwise.
Still logically false. Determinism never eliminates any possibility of doing otherwise. The possibility of doing otherwise never requires that we actually do otherwise, but only that we can do otherwise if we choose to. I chose the salad, but I could have chosen the steak. The steak was a real possibility, and my choosing it was really possible, even though I would never choose it under those conditions.