I'm not sure I understand your point. Let me try to summarize where I think we are.

Problem 1: Either some perceptions are true, or else all could be an illusion.
Solution 1: Appealing to Principle of Parsimony, the former is more reasonable than the latter. It thus becomes the Prima Facie.

Problem 2: Some perceptions are true, but we know some are not (e.g sometimes my eyes fail me when I've been drinking). How to validate the perceptions?
Solution 2: Appeal to the Principle of Universal Perceptions. If the perceptions pass the PUP, then the belief that the perceived object is real becomes the Prima Facie.

Is there a problem still pending?

YES. [...] — unenlightened

Well I am genuinely impressed. Nevertheless, this lack of trust, of assuming dishonesty until proven otherwise, is unreasonable. It fails the Presumption of Innocence. And I still maintain that most scientific demonstrations cannot be replicated by most people. If a cancer expert diagnosed you with cancer, would you spend the time to replicate the test yourself prior to going for treatment?

It comes to the same thing. Subjects can only know they perceive the same thing by communicating. — unenlightened

This also applies to some scientific tests such as testing new painkillers. Anyways, I'll do you a solid. Let's add the condition that the PUP is valid as long as the subjects are honest.

Here's one you can do yourself on your next holiday. [...] — unenlightened

This demonstration presupposes that the sun is far away from the earth. Flat Earthers would disagree. :razz:

You could as well have said "Hume says this, but clearly it is absurd, therefore he is wrong". — Echarmion

Not necessarily wrong. It just means he has the onus of proof. Absurd, common sense, reasonable, status quo, all these are terms which serve to establish who has the onus of proof. Once the onus of proof is fulfilled, then the claim stands, even if it is absurd.

Oh that's clever. So you get to set the status quo and then get to ask everyone for proof? — Echarmion

I don't set the status quo. I discover it by experience. If you want to be formal about it, you could survey what most people believe about hallucination and the normal. My money is that hallucinations are not seen as normal.

the teapot is too small to be revealed even by our most powerful telescopes. — Echarmion

Practical limitation does not entail that a thing is theoretically unobservable; unlike spirits for example.

Dictionary definitions are not arguments. That's how the term is generally used. Hume essentially questioned whether that use was actually correct. — Echarmion

My discussion, my rules. By objectivity, I mean "external reality" as per the dictionary, and that's how it will be used in this thread. :cool:

I don't think that those are the two only options. When discussing metaphysics a "true agnostic" position exists, i.e. there are simply things we can't make reasoned statements about one way or another. — Echarmion

Unfortunately, if you don't make metaphysical claims, then philosophy is impossible: Metaphysics is the science of what is real. If no knowledge of reality, then no truth (defined as conformance to reality), then no philosophy (defined as search for truth).

And actually... I just realized that the Principle of Parsimony is nothing but Abductive Reasoning, which is a fundamental law of thoughts.

Precisely. A rainbow of wisdom.

we can only perceive perceptions — Wolfman

So you claim that when we perceive an object, it is never the object in reality. And why would that be? If it looks, sounds, and feels like a duck, is it not reasonable to believe it is in fact a duck, until given a reason to believe otherwise?

Hello.

This is risible. — Banno

Give it time. It will grow on you.

I think you are inconsistent. If you claim that all subjects for the PUP can lie, then all scientists can also lie. How do you know the Earth is round? Did you conduct the demonstrations yourself, or do you rely on the claims of scientists?

Regardless, this is a misunderstanding about the PUP. As described in the OP, it states that "if a large majority of subjects perceives the same object, then [...]". It says "perceives", and not "claims to perceive".

"common sense" won't fly in a serious discussion. — Echarmion

I cannot agree with you there. Have you heard of the "absurd"? Reductio Ad Absurdum? All valid philosophical terms which criteria of judgement is common sense or common life experience.

You have to actually give reasons why it's "not normal" to hallucinate. — Echarmion

No sir. The onus of proof is on he who disrupts the status quo, and the status quo is that it is not normal to hallucinate.

For example, one might say that statements of existence or nonexistence about an object which is defined as unobservable are equally meaningless. — Echarmion

How is a teapot unobservable?

The problem Hume brings up is exactly that there seems to be nothing connecting reality (the things we experience) and objectivity. — Echarmion

Are you confusing the terms objectivity and subjectivity perhaps? Objectivity is defined as "external reality". Source

Philosophy isn't necessarily concerned with predictions. Epistemology, for example, is concerned what we can know, not what we will know. — Echarmion

True. I should have said that both science and philosophy aim for truth, which is conformance to reality.

But regardless of it's origin, the principle must stand for itself. — Echarmion

As previously mentioned, it is defended by the fact that the alternative method (that more complex explanations are more reasonable until proven false) leads to a reductio ad absurdum. Can't prove that invisible unicorns don't exist? Then they exist. And please don't ask me to defend the reductio ad absurdum principle, because we will then have a case of infinite regress.

This is definitely a tangent, but... let's do it.
I think I have a clear enough understanding of the distinction between belief and guess, supposition, and estimate. But what is the difference between belief and opinion? Genuinely asking.

on Hume’s view, there is a problem with how perception operates in the first place. — Wolfman

What problem would that be, that is not covered by the PUP?

And you don’t do this by appealing to the very system he says is flawed — Wolfman

The Principle of Parsimony is flawed? Why is that?

Something that might help in general: The first line of the OP on Hume merely served as an introduction to present the PUP. I am not really looking to refute a claim by Hume, but to determine if the PUP is valid.

Hello.
If I understand your post correctly, you say the PUP fails against radical skepticism, because the explanation of collective hallucination already presumes some things about reality, such as the reality of other subjects, where as the evil demon theory is more radical and makes no presumption about reality (except for the existence of said demon).

This is true. But although outside of the PUP, the evil demon theory also fails the Principle of Parsimony (which falls under rationalism and not under perceptions) which the PUP is also based on, because positing the existence of an evil demon is more complex than not.

I know that people lie — unenlightened

The fact that is it possible for people to lie does not count against the PUP. It is like saying that the scientific method is flawed because scientists who apply it can always lie about the results.

I will trust my eyes [...]
I know that [...] people see what they want to see — unenlightened

Don't these two sentences contradict? Unless you say you are above the second claim; and indeed, that does sound arrogant :joke: .

people conform. — unenlightened

This is true, and we must take it seriously. Fortunately, it can be controlled by doing things like a double blind test, etc.

So...your point is? — Frank Apisa

That I think you are applying the PUP when you say you are more inclined to pick scenario (1) over (2). We are in agreement that reasonableness does not give certainty, but it is powerful enough to tip the scales.

Now...the answer I would much prefer. Neither! I do not do "believing"...by which I mean I NEVER EVER say that I "believe" anything. — Frank Apisa

This is an aside, but I want to say that your demand for certainty, all or nothing, is unreasonable for this world. Sure, this horse experiment is not consequential, but a lot of things are. We are not certain that Climate Change is real, but being agnostic is not a choice in this case. Either we fight it or we don't. And a 97% agreement among experts (let's assume that part is true) is sufficient to pick a side.

Hume would simply say more people [...] are mistaken. — Wolfman

Why is this claim the most reasonable one? Appealing to the Principle of Parsimony, you (or Hume) have the onus of proof to defend it.

"I'm hallucinating" is a very simple explanation — Echarmion

No because it is abnormal (using common sense alone, the normal is to not hallucinate), and so we would need to further explain the cause of that abnormality. In contrast, we don't need to further explain the existence of an oasis, as it is not abnormal.

while I am hallucinating, perhaps I am also hallucinating the people that agree with me. — Echarmion

Might as well believe that the whole world is an illusion, on the mere grounds that it is logically possible. But logically possible does not entail reasonable. For this, we appeal to further principles of reasonableness like Parsimony.

The bigger issue is that you haven't justified the principle of parsimony. Why is the less complex explanation closer to reality? Is reality obligated to be simple and parsimonious? — Echarmion

This discussion defends the PUP on the grounds of Parsimony, which is indeed assumed. I am hesitant to defend that here, with fear that I would need to defend the premises for Parsimony etc. All I will say for now is that it is a perfectly accepted scientific principle, and that the alternative (that more complex is more reasonable) leads to a reductio ad absurdum: Can't prove there is no teapot in space? Then we'll believe there is.

The reason we can use the parsimony as a principle in the scientific method is because we're concerned with making predictions, which means making working models of reality. A simpler, more inclusive model is more useful than a complex, less inclusive one. But it's a tool for of practicality, not objectivity. — Echarmion

I'm not sure that statement makes sense. Reality implies objectivity. And as both philosophy and science aim to predict reality, what works for science for that aim also works for philosophy. Note also that the Principle of Parsimony was first introduced not for science but for philosophy; and that science is a branch of philosophy (ie the search for truth), specializing in what is empirically verifiable.

Hello.

Hume notes that the only things we can perceive are perceptions (i.e. internal and perishing existences), but the vulgar confuse perceptions with actual objects; that is, they confuse representations with what is actually represented. — Wolfman

Sounds good; I accept the correction on Hume's position. Then the PUP also solves that new problem; that the actual objects can reasonably be predicted if the perceptions are consistent among the subjects.

Yeah sure. That "problem" line was more of an intro to present the principle.

Anyway, I would like to be clearer about what exactly is the position you're attributing to Hume before considering whether what you are proposing is or is not an answer to it. — Nagase

It seems I have trouble clarifying to you what I think Hume is saying. But in a way it is not relevant, for the point of the OP is not to determine if I answer Hume's problem, but if the PUP is a valid principle.

This is admittedly nitpicky, but doesn't "knowing" imply certainty? Math is indeed certain. But for the horse story, there is the alternative possibility of collective hallucination (though of course nobody in their right mind would choose it I think).

That aside, whether we use the word belief or knowledge, it sounds like it is a yes. Now consider 2 scenarios with 10 subjects trying to determine if there is a horse in a field:
(1) 9 out of 10 subjects see a horse; the other 1 does not.
(2) 1 out of 10 subjects see a horse; the other 9 do not.

In which of the 2 scenarios is it more reasonable to believe the horse is real?

Hello.

You say a collective hallucination is "less likely" but what is that judgement based on? If you're basing it on empirical research on hallucinations, then you're just referencing another phenomenon, which might be just as illusory as any other. — Echarmion

I think I understand your point, that to quantify the likelihood or probability of hallucination demands a reference that must be more certain. But rather than using Probability, I am using Complexity of the explanation to appeal to the Principle of Parsimony. Regardless of the probability, the explanation that the object is real is simpler than the explanation of collective hallucination, because it would also need to explain where the hallucination comes from, and how come it is so consistent among all subjects etc.

Another example of using complexity instead of probability for reasonableness: If an object looks and sounds like a duck, it is more reasonable to conclude it is a duck than to conclude it is a robot piloted by an alien. This is not because we know the probability of that explanation, but its level complexity.

That is some Sixth Sense stuff right there! You may relax and know you are real because Cogito Ergo Sum. Even Bruce Willis was real; just not visible.

if one can hallucinate a unicorn, one can surely equally hallucinate a crowd of other people — unenlightened

True. Unless you have confirmed before that the crowd is real (through interacting with them in the past, or seeing, hearing and touching them, etc). Let's say that's the case here.

Also, if stuck on the unicorn idea due to it being inconceivable, then let's use a horse instead. Is it more reasonable to believe that the horse is real, or that it is an hallucination along with everyone else in the room and everything else you know in this world?

The idea that reality is to be decided by a vote is repugnant. — unenlightened

I agree only when it comes to votes based on opinions without reason. Otherwise, we do this all the time, and reasonably so. If 9 out 10 cancer experts claim you have cancer, is this not grounds to take the claim more seriously than if it was 1 out of 10?

No. He claims that you cannot draw conclusion about reality from perception.

Still missing the point. Let's tweet the story some more.
Replace unicorn with horse; replace room with "field on the other side of the fence" (so that you cannot verify its existence by touching it). You still wouldn't believe it is real?

I think he is in fact denying there is any connection between perception and reality. To him, making any claims about metaphysics is impossible.

Hello.
But some things CAN be perceived. And the PUP connects the perception to conclusions about reality, which is metaphysics.

Hello.

What they wonder is whether or not what they see is a mirage, which is a form of illusion, not a hallucination. — unenlightened

This is missing the point (which admittedly with hindsight is unsurprising when using the desert example). We could have used the perception of a unicorn in a room instead. If I am the only subject, then I would second-guess my perception, but if many subjects perceive the same unicorn, then it is reasonable to suppose that it is real, until given a reason to believe otherwise.

Furthermore, the case of a mirage does not work against the PUP. First, if there is a mirage of an oasis, then the oasis must still exist. Second, different subjects are not expected to perceive the mirage-oasis in the same fashion if they are seeing it from different locations. Third, is it not still more reasonable to believe the perceived oasis is real, if given no reason to believe it is caused by a mirage? Remember the PUP gives reasonableness, not certainty.

Hello.
Yes, this "intersubjective agreement" is very much what I am trying to describe in the PUP.

Hey there.
I am not sure if your post is intended to address my quote, but if it is, I must admit I don't understand anything you are saying. Sorry bro. Perhaps it could be a bit more concise?

Hello.

So how does the fact my mind does not appear to be my body provide evidence that my mind is eternal? — Bartricks

This is not in the OP, but here is my answer. It does not claim that the mind is eternal (for I believe it begins to exist), but that it survives the event of death.

- The human body can be defined as "all the physical parts of a person".
- Thus if the mind is not the body, then it it follows that it is non-physical.
- Since death is, as far as we know, only a physical event, then it does not affect non-physical things, and thus the mind must survive death.

So you claim that subjective topics, that is, matters of opinions, regard things for which we have little-to-no experience or knowledge, is that right?

I disagree with that. Sticking with the same apple example, even if we both take a bite out of the same apple, I can still make the honest claim "this apple tastes good", and you can make the honest claim "this apple tastes bad"; and this can simply be explained by the fact that I happen to like apples and you happen to dislike apples in general. Another classic example: we both look at the same piece of art, and you claim "this is beautiful" and I claim "this is ugly", and neither of us is wrong, because as the saying goes, beauty is in the eye of the beholder, that is, the subject.

Conversely, I can have zero knowledge and experience about angels, and yet making a claim such as "angels exist" is objective, because it is a matter of fact: they either exist or they don't.

Greatest degree: I know falling out of a tree certainly can hurt because I fell out of a tree once and it hurt like hell.
Lesser degree: I believe falling out of a tree hurts, but never having fallen out of a tree....I might get lucky, fall on a pile of leaves, and suffer no hurt.
No degree at all: experience and possible experience having been accounted for, there is no other degree of truth available, so there is no opinion on falling out of trees. Nevertheless, it is my opinion these statements are true. — Mww

Nevertheless, I mostly agree with these above statements on the degrees of knowledge. I would call the top one "certainty", the middle one "probability or reasonableness or methodical faith", and the last one "blind faith".

Assignment of a property to an object is indeed the activity of a subject, but I don’t think it is merely a matter of opinion. — Mww

That depends on the properties; but maybe the term "property" is confusing. It could be replaced with the term "predicate". Here are examples of subjective properties/predicates:
This song is good. This joke is funny. This story is interesting. Strawberries taste better than bananas.
People could disagree with all these statements, and there would be no right or wrong.

Contrast it with the following examples of objective properties/predicates:
This song is 5 minutes long. This joke is stolen from someone else. This story is in english. This strawberry is smaller than this banana.
If someone disagrees with these statements, then one person must be right, and one must be wrong.

Have you noticed that the propositions “This apple tastes good" and "Samuel thinks this apple tastes good" have the same message, and yet the first one is subjective and the second one is objective?
— Samuel Lacrampe

I’ve noticed it now, insofar as the message is the telling of something about the taste of apples. I’ve also noticed that seemingly the first is objective and the second is subjective. — Mww

To clarify, I am using my definitions of objective/subjective here. So the first proposition is subjective because it is a mere matter of opinion - some people could claim that this apple does not taste good; and the second proposition is objective because it is a matter of facts - it is either true or false that I think this apple tastes good.

reductionism mandates that for the simplest objects, or complex objects perfectly congruent, the particularity of identity reduces to the space and time of it. — Mww

I think this reductionist idea seems correct. If the cause of individuality is the particular matter, and no two physical things (which matter belongs to) can occupy the same space at the same time, then it follows that no two particulars can occupy the same space at the same time. As such, finding the space property of things at a given time is a good way to determine if things are identical or distinct.

E.g. You saw a brown dog at such time, and I also saw a brown dog at that same time, but yours was at location A where as mine was at location B. This is sufficient to conclude we saw two different dogs.

The subjective conscious activity is reason in general, and opinions, beliefs and knowledge are mere matters of degree reason judges of truth. — Mww

Understood. So one definition of subjectivity can be something like "an act that is internal to the thinker (the subject), and is not reducible to a physical act"; and a second definition can be "a property assigned to an object, that is merely a matter of opinion from the subject".

These two definitions overlap in that they both involve an internal act from the subject, but yet seem to be different enough to remain two separate definitions. Shame...

Wonder what the opening salvo would be. — Mww

Here's a candidate.
Have you noticed that the propositions "This apple tastes good" and "Samuel thinks this apple tastes good" have the same message, and yet the first one is subjective and the second one is objective?

If you call out, “here Sparky!!” and I call out “here, Fido!!”, the dog comes to you but ignores me, we have gone further than the establishment of identifying a general conception, that is, we have given an identity to a particular instance of a general conception. — Mww

That's right. This would be naming a particular, for which the main cause of its individuality is the particular matter that dog is made of. That's all that is needed for an object, such as a particular soccer ball. I think in the case of a dog, we could also add its particular set of memories and habits.

At the end of the day, when it’s all said and done, we cannot abide being confused with something that is otherwise identical to us. — Mww

I think we're safe, because I hold that as long as we are made of particular sets of matter, then we are particulars. But things get ... fun, when that matter gets substituted. E.g. I heard that all the atoms in our bodies get replaced every 7 years. This recalls the puzzle of the Ship of Theseus.

Close, but a little further down the line. I agree to identifying a thing by its name, which is the same as my conception of it. Or, I identify a thing by means of its concept. [...] — Mww

I think that is correct. In addition, we name general concepts with common nouns, (e.g. a dog) and particulars with proper nouns (e.g. Fido). The identity of general concepts is their essential properties, and the identity of particulars is their essential properties plus their particular matter. E.g. Pointing to a particular set of matter when saying "Fido is that dog".

Agreed. But what is it that is lost? That is, of what is identity comprised? What is an essential property? — Mww

I think you are asking how to determine if a property is essential or not? In general, a property is essential if, should that property be lost, then the thing would lose its general identity (called "species" as per Aristotle). This can be tested in a thought experiment. Say a particular triangle is made of the following set of properties: "surface with 3 straight sides" + "yellow". If the triangle loses the first property, it is no longer a triangle, where as if it loses the second property, it remains a triangle. Therefore the first property is essential, and the second one is not.

For the objectively valid, the conscious activity of a thinker, the internal domain, is responsible for those objects of reason, which is subjectivity. For the objectively real, the world, the external domain, is responsible, for all that which occurs without any thinker. — Mww

Interesting. While I think your definition of "objectivity" matches with mine, it doesn't quite match for "subjectivity"; because the activity of a thinker is not necessarily a mere matter of opinion; neither in act (it is either true or false that I am thinking), nor in content (my thinking process could be right or wrong). I'll think about it some more and see if the definitions can be reconciled somehow.

Which is why metaphysical investigations are so much fun. How to tell the difference, and what to do about it when the difference is told. — Mww

Yeah this is could be a whole discussion in itself.

If I don't reply to some of your previous paragraphs, it is implied that I agree with them.

[...] are identical twins one-and-the-same? Even if their parents couldn’t tell them apart by their properties, is it permissible thereby to say they have the same identity? — Mww

No; in the sense that I give, "two" things would be identical if they are numerically one. E.g. you say you saw a brown dog at such time and such place, and I say I saw also saw a brown dog at the same time and place, then we conclude that your dog and my dog are identical, that is, we speak of the same dog. In the case of identical twins, "identical" just means that all or most of the properties are similar, yet the twins are numerically two. I'm okay using the term identical in either sense, so long as we are on the same page.

I doubt you think of yourself as “Samuel LaCrampe” just because you are a certain height, because “Samuel LaCrampe“ has been many heights. — Mww

Correct. While I believe that things must have the same identity to be identical, the reverse is not necessarily true. I retain my identity even if I have a few different properties from 2 years ago. The answer, as per Aristotle, lies in the distinction between essential properties and non-essential (or accidental) properties; where if you change non-essential properties, like weight, you retain your identity, but if you change essential properties, like dying, then you lose your identity.

Therefore, some other condition must determine why we are separately identifiable as particulars in the set of all general instances. — Mww

As per Aristotle again, when it comes to things other than persons, the cause of particulars is the matter. E.g. two triangles are numerically two because they are composed of separate atoms. When it comes to persons, I add the soul in addition to matter as the cause of particulars or individuality (but we can leave that can of worms alone).

What do you mean by subject of thought? [...] I offer subjectivity to be the conscious rational activity of a thinking subject. The object of thought is a cognition, an empirical cognition grounded in phenomena is an experience, a rational cognition grounded in abstractions is a judgement, all of which requires a thinking subject, that to which those cognitions, without exception, all belong. — Mww

Ah. So subjectivity means abstract, rational, non-empirical ideas, and objectivity means empirical things, is that more or less correct?

So we are not on the same page on these terms. Here is what I mean. "Object" is the thing observed, thought about. "Subject" is the observer or thinker. E.g. when I think "This apple is round", the object is the apple; the subject is me. From there we get the terms "objective" and "subjective", where a property is objective if it is about the object, and subjective if it is really about the subject. In the previous thought, the property "round" is objective, because roundness is a property of the object. On the other hand, in the thought "This apple is interesting", the property "interesting" is subjective, because it is really saying something about me when I think of the apple, ie, the apple interests me. Objective claims are about reality, and can be true or false, right or wrong. Subjective claims a mere matters of opinions, and cannot be true or false, nor right or wrong.

How about perceiving two things that each have 4 legs, wings, and speaks. It is entirely possible for such things to exist, because there is nothing contradictory about them, which makes explicit the possibility of perceiving them. Damned if I would know what they are [...] — Mww

It sound to me you equate the identity of a thing with its name. In your example, you can describe the things by listing their properties, but then the only thing missing is what they are called, am I correct? A name is only a symbol or sign that points to the identity, but is not it. E.g. say I just learned to speak english, and don't know what the word "bird" means, ie, I don't know what identity it points to. You describe it by saying it is the type of animal that has two legs, a beak, feathers, and can fly. I say "Ah! I get it. We call it 'oiseau' in french." You have described its identity by listing its properties, and now I know it.


Sorry for the long post.

[...] no metaphysical proposition can be shown to be valid without empirical justification. — Mww

If by that you mean the original data must come from empirical observations, then I agree. If you mean that the concluding metaphysical claim must be empirically verifiable, then I disagree. What is metaphysical is not directly observable; it can only be deduced.

Then you should be able to tell me about a real thing unknown to you. — Mww

Of course I can't do that; but I can tell you about a real thing that existed before I knew about it: dinosaurs. My point is that the existence of a thing is not caused by our knowledge of it. So in the stool example, it doesn't matter if a subject does not know if the stool was previously assembled or not.

Then why are you and I not identical? Are our respective identities really from the properties we have in common? — Mww

No; the opposite: our identities are distinct precisely because you and I have different properties. Matter, for one thing: my body is not yours. Then a few other properties I'm sure, like height, weight, etc.

It follows that if either class has even one incongruent thought (properly conception) or perception (properly intuition), the things cannot be identical, for the simplest of reasons that they cannot have the same identity. Assuming correct judgement, naturally. — Mww

I agree with the perception part (assuming true perception), because this informs about a property of the object perceived. But I disagree with the thought part, which I believe you categorized as subjective. Subjectivity by definition refers to the subject of thought, not the object of thought.

Furthermore, whether we grant two things are identical or not, we are given nothing from that, that we can use to establish the identity of just one of them. I can perceive two things which seem identical without knowing what those things are. — Mww

How could that be? As per P1 from this post, "identical" means they have the same identity, which is the list of their properties. It follows that the identity must be known in order to determine if the two things are identical. Could you give an example where we perceive two things which seem identical without knowing what those things are?

I don't understand why you are bringing knowledge and perception in a metaphysical topic. A thing is real/not real independent of our knowledge of it. In my hypothetical example of the stools, it is about facts, not perceptions. Let me try one more time to clarify the reasoning.

P1: "Two" things are identical or one-and-the-same if they have all the same properties that make their identity.
P2: Stool(t1) and stool(t3) as described here have all the same properties.
C: Stool(1) and stool(t3) are identical, one-and-the-same.

Correct me if I'm wrong, but my guess is that your objection is with P1. But in which case, what is your definition of "identical"?

I think your understanding of my scenarios is correct. But now I'm thinking the example of snowball is not adequate, for its complexity creates tangents such as spacetime non-equivalence, Feynman’s sum over histories, and other things I don't fully understand but are likely not relevant for the current enquiry.

Let's try again with a simpler example. Consider a stool composed of only 5 parts: 4 legs and a sit. The stool at time t1 is fully built, then deconstructed into its 5 parts at time t2, and then reassembled with its original parts at time t3. The question is: Is stool(t3) identical to stool(t1)? I would say yes, for all the properties are the same (with the exception of time, but time is not really a property of the stool).

Based on the quote below, I understood that your answer would be no. But maybe I misunderstood?

If I make a snowball, heave it at the barn wall and it explodes, it has immediately ceased to exist as a snowball. If I gather up all the snow from the former snowball, make another snowball from that, there is then a snowball containing the constituency of the former, but not the identity of it. A snowball exists again; the snowball really does cease to exist. — Mww

To be clear, by "identical", I mean not that they are similar, but that they have the same identity, that is, they are one-and-the-same.

With that, two snowballs side by side would not be identical, because even though they share the same properties of material, size, and shape, they are not composed of one-and-the-same matter (ie they have distinct molecules of snow). But when we compare the snowballs in the two hypothetical scenarios previously described, they are then composed of one-and-the-same matter. So it would seem in that case it is correct to call them identical. Granted they have different histories, but this is like two different paths leading to one-and-the-same location.

If I make a snowball, heave it at the barn wall and it explodes, it has immediately ceased to exist as a snowball. If I gather up all the snow from the former snowball, make another snowball from that, there is then a snowball containing the constituency of the former, but not the identity of it. A snowball exists again; the snowball really does cease to exist. The arrow of time does not allow snowballs in general to exist, cease to exist and exist again as the same thing. — Mww

If I may. This is a nice illustration, but how does it demonstrate that the second snowball is not identical to the first one? Let's call your scenario scenario 1. Let's compare with scenario 2, in which the initial snowball was never thrown at the wall, thereby never got destroyed. What is different, property-wise, between the final snowball from scenario 1, and the snowball from scenario 2?

How can pre-existence have a property? — Yohan

The term "nothing" is defined as "that which has no properties". Insofar that pre-existence is not nothing, then it has some properties. Or another way to look at it, if a term is not meaningless, then it has an essence, that is, some essential properties.

How can non-existence BE a property? Do not only things have properties? Non-existence isn't a thing. It refers to an absence of thing. Or rather, it tells you that not anything is being referred to. Like a finger that isn't pointing at anything. — Yohan

Sure, you are correct. "Non-x" is the absence of x. So pre-existence is similar to non-existence in that they both lack the property of existence.

Explain to me how an empty bowl is any way different than a pre-filled bowl. — Yohan

As mentioned above, the essence of a term is found by listing its essential properties. The essence of "empty" can be "absence of being filled". The essence of "pre-filled" is "absence of being filled" + "potential of being filled that will be actualized eventually".

A unicorn and a phoenix are exactly the same while NOT existing. — Yohan

This disagrees with common sense. In real life, neither a unicorn nor a phoenix exist, and yet the definition of a unicorn is different than the definition of a phoenix. The only property (or lack there of) they share is the absence of existence. To use yet another example: A bowl is empty; a bottle is empty; yet a bowl is not identical to a bottle despite both being empty.