An unusual phrasing, but I supose modal logic apples to impossible worlds and is what shows them to contain the contradictions that render them impossible.If all we wish to do is save any aspect of modal reasoning so as to avoid absolute collapse, we have to show such a thing as modal reasoning exists in impossible worlds. — Hanover
Yep.That is, can I not logically reason based upon the antecedent without the antecedent being true in this world? That seems what modal logic is. — Hanover
Now, in the present, certain things have certain potentials. Joe might potentially be asleep at 10 PM or be awake then. A rock, by contrast, cannot be asleep or awake. So, we can speak about possibilities in the future according to the ways in which things in the present possess potentiality. — Count Timothy von Icarus
This is nitpick, but is the definition of "rock" so clear and tight that it cannot allow for the logical possibility of a rock being asleep or awake? I'm thinking of Rock Biter in the movie The NeverEnding Story.So, in no possible world is there a rock that is asleep or awake, and so no world is accessible in which the rock is awake. — Banno
If it rains, I'll get my umbrella is modal logic, and it may or may not be raining at the moment or ever again in the future. Why do these temporal issues of what is happening now or later interfere with our ability to logically assess? That is, can I not logically reason based upon the antecedent without the antecedent being true in this world? That seems what modal logic is. — Hanover
But surely ↪Metaphysician Undercover, there is a way to do counterfactual reasoning, right? So, "if this plant was not watered, it would not have grown." But the plant in question has to be, at least in some sense, the same plant, or else we would just be saying that if the plant was a different plant it might not have grown. — Count Timothy von Icarus
Likewise, in counterfactual reasoning, we speak to the potencies that some thing possessed in the past, and then discuss what would be true if they were actualized differently. — Count Timothy von Icarus
The past is, in some sense, necessary, having already become actual. But when we speak to "possible worlds" with a different past, we are simply talking about different potentialities becoming actualized. — Count Timothy von Icarus
That's the point. You allow indexation for time, but not for possible worlds. Why? — Banno
I hope it is clear, and as the Roman example given above exemplifies, possible worlds can be about the past as well as the future. If we accept rigid designation, the possible Caesar who did not cross the Rubicon is the very same as the actual Caesar who did. That that is, "what might have happened if Caesar had not crossed the Rubicon" is a question about Caesar, and not about some other person in some other possible world who happens to have the same name. — Banno
In trying to throw out the bath water of fatalism, you have wholly thrown out the babe of modality. And needlessly, since accessibility allows us to make choices. — Banno
It handles a wider range of modalities, cleanly avoids category mistakes, and is rigorous enough for computation. — Banno
Okay, that makes sense!We have a choice here, not about whether rocks sleep so much as about how we use the word "rock". — Banno
That is classic logic, not modal logic, though, correct? I understand that if we're referrring to what might be we can't set it out in terms of what it currently is. The antecedent is conditional, and it is useful to logically determine an outcome on a possible world because we require that sort of logic to make our decisions.This future scenario, of me carrying an umbrella at 7AM tomorrow morning, is neither true nor false, and Aristotle described it as a violation of the law of excluded middle. — Metaphysician Undercover
Your objection is that the hypothetical possibility is not ontological in existence and so you therefore cannot logically consider it? This I don't follow. Why can't we logically assess possible worlds that aren't actual worlds? This is the point of modal logic.I believe this is because the object, as thing spoken about, has no temporal extension into the future, and therefore has no identity in that direction beyond the present. To say that there is an object, with an identity, in the future, is a false proposition due to the reality of future possibility. — Metaphysician Undercover
I have no problem with modal logic. — Metaphysician Undercover
Can we agree there's a first cause and an irreducible bottom layer of reality? If we start with that assumption - and call it the "ontolgoical ground" (OG), we can then entertain some possibilities. But first, let's consider whether or not the OG exists contingently or necessarily. (in all cases, I'm referring to metaphysical necessity/contingency, not to confused with conceivability or conceptual modality).if the fundamental laws of nature existed inherently, this would result in a modal collapse, which is usually frowned upon. Therefore, the existence of the fundamental laws of nature are explained by design (type 2), and for a specific purpose. — A Christian Philosophy
Can we agree there's a first cause and an irreducible bottom layer of reality? — Relativist
That is classic logic, not modal logic, though, correct? I understand that if we're referrring to what might be we can't set it out in terms of what it currently is. The antecedent is conditional, and it is useful to logically determine an outcome on a possible world because we require that sort of logic to make our decisions. — Hanover
Your objection is that the hypothetical possibility is not ontological in existence and so you therefore cannot logically consider it? This I don't follow. Why can't we logically assess possible worlds that aren't actual worlds? This is the point of modal logic. — Hanover
You say this, but your objections are directed straight at it. — Hanover
It is not a rejection of modal logic, it is a rejection of the way that modal logic is often applied. To apply logic correctly requires ontological principles. Demanding ontological clarity of the meaning of propositions before performing logical functions is not a matter of rejecting the logic. It is a matter of requesting an adequate explanation of the premises, similar to asking for definitions. If an important term like "possible" is left with ambiguity between two very distinct senses, this is cause for concern, because it allows for the possibility of misuse.You demand ontological reality upon your propositions prior to performing logical functions on them, which is an outright rejection of modal logic. — Hanover
That's fine, but it's not an objection about anything inconsistent with modal logic. It's just a refusal to accept it as a mode of reasoning. — Hanover
This is just to say that if you insist upon actual worlds for the conditions to exist in to perform logic upon them, then you're refusing to consider possible worlds, which is what distinguishes classical and modal logic from one another. — Hanover
Instead I think there are a multitude of possible worlds, but that there is one possible world amongst them that is actual. I take this to be the most common view, almost to the point of a consensus. — Banno
what I am saying is that modal logic is not consistent with classical logic. — Metaphysician Undercover
Trouble is that modal logic includes propositional logic and predicate logic. Every valid proposition in propositional logic and in predicate logic is valid in modal logic. And for every valid syllogism in classical logic there is an equivalent valid formulation in propositional or predicate logic. — Banno
If you insist that modal logic fails because of its failure to adhere to classical logic standards related to ontological status, then you will be de facto rejecting modal logic. — Hanover
Modal logic admits to the incompatibility noted by Aristotle and responds to it, so I don't know how to respond other than to say if you want modal logic to act like classic logic you can't have model logic. — Hanover
In any event, give me a syllogism in modal logic you feel fails by giving an illogical result due to its adherence to modal logic standards and not classical so I can see concretely why you object. — Hanover
Because he's a Christian, he believes there is an OG. I am arguing that an OG does not entail a God.Why? — Banno
All propositional, predicate, or classical logic can be expressed as modal logic. — Metaphysician Undercover
Can you show that there is no OG? — Relativist
Perhaps some things just are the case, unexplained and unexplainable. — Banno
Yes: OG = ontological ground. I don't need to demonstrate there is an OG to someone who already believes there is one.don't know. What's an OG? An ontological grounding...?
And wouldn't it be incumbent on those positing an OG to demonstrate the need for one? — Banno
It really would help if you were to read about and try to understand logic rather than just dispensing your wisdom. — Banno
Fuck the logic, it doesn't qualify as wisdom so why waste time trying to understand it, when all that has ever done is produce faulty interpretations. It's best to leave logic as it is, impossible to understand. — Metaphysician Undercover
Yes, I agree that there is an OG.Can we agree there's a first cause and an irreducible bottom layer of reality? If we start with that assumption - and call it the "ontolgoical ground" (OG), we can then entertain some possibilities. — Relativist
I am unclear from your comment whether you agree with the conclusion from the OP, that the fundamental laws of nature must be designed. If so, then we can infer that the OG has the faculty of being a designer; which in turn implies a free will, because beings that are not free cannot produce things out of design.You believe God is the OG, and probably agree it's existence is necessary, but there's no reason why it couldn't be something natural that includes the fundamental laws of nature in its structure. — Relativist
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