Though the details have changed, concern about the effect of modern civilization on our world has been around a while. When I was kid, the concern was pollution. (I looked it up--the "crying Indian" PSA was 1971.)

So there's continuity there, but also difference. There was this sense 40 years ago that we could (a) stop messing up the planet, and (b) clean it up. Now we know that (a) is a lot harder because it's not littering or the occasional bad actor illegally dumping toxic waste that's the problem, it's the fundamental driver of modern civilization, i.e., burning fossil fuels. And it turns out (b) might not be an option, if we can cause permanent, irreversible damage.

So in a way an environmental activist from 40 years ago could say now "I told you so," but in another way they were probably wrong at the time about the two most important points. Talking about the future is almost always like that--even when you're right, you're wrong.

It's as if you derived Fx and derived Gx, then used &-introduction to get (Fx & Gx), and then told us that you could prove Fx from (Fx & Gx). You can infer Fx from (Fx & Gx), sure. That's just &-elimination. But you could only truly assert (Fx & Gx) in the first place because you could already truly assert Fx and you could already truly assert Gx. Do you see the difference?

You're missing the point.

You have claimed that "one truth about x proves x exists," and given a reconstruction of the cogito along these lines.

Presumably if you are trying to prove x exists, you don't know yet. In particular, you don't know yet whether the expression "x" refers. Your method was supposed to show that "x" refers. (Because it is true that Descartes is thinking, Descartes exists.)

If you must already know that the expression "x" has a reference (the object x) in order to know that "Fx" is true for some F or other, then you are not proving x exists, you are presupposing it.

Of course you can infer from the truth of "Ga" that G is a real predicate and a is an existing individual. But that's not proving anything. You already knew all of that.

I summon Hume's principle that there are no innate ideas, that all conceptions must come from experience; and thus anything that we can conceive must exist at some point. This does not mean that just because I can imagine a unicorn, that unicorns exist, but that the basic components of the unicorn (colours, shapes, sounds, ...) must exist. — Samuel Lacrampe

I have been unable to find a source for the clause beginning "thus." I don't think Hume says anything like this, and it clearly does not follow from the summary of Hume's view of the imagination that you've presented. If you want to keep relying on this idea, you'll need to argue for it without Hume's help.

Maybe you could give me an example of an object causing another to exist, so I know what you mean. — Srap Tasmaner

Nevermind, I've got it.

I just caused that sentence to exist. It has the property of being composed of words; I am not composed of words.

If it is true that unicorns have four legs then unicorns exist.
Truth is that which can be shown to be the case.
To show that 'Unicorns have four legs' is true, we need to verify it.
Verification requires the existence of unicorns and unicorn legs.

One truth about x proves x exists. ..where x is the subject of the truth. — Owen

Suppose I claim there is a smallest positive real number, call it k.

It's easily proven that k < 1, right?

Does that prove that there is a smallest positive real number?

Using the law of noncontradiction, either a thing has a cause or not. This is true regardless if the thing is observable or not, because the law of noncontradiction is an absolute. — Samuel Lacrampe

The law of contradiction would say, roughly, that nothing is both caused and uncaused. You're using the law of the excluded middle. I know it might seem like they're the same thing but they're not.

I think we would get too far into the weeds going through this here, but here's a quote from Michael Dummett that should give you some idea what I have in mind:

Unless we have a means which would in principle decide the truth-value of a given statement, we do not have for it a notion of truth and falsity which would entitle us to say that it must be true or false.

So you should at least be aware that there are philosophers who have qualms about drawing "logical" conclusions about matters we can in principle know nothing about.

Maybe you could give me an example of an object causing another to exist, so I know what you mean.

let's provisionally accept that the statement 'no effect has a property not possessed by its cause' is not patently false, until either a clear exception arises, or a flaw is found in the reasoning of the original argument here. — Samuel Lacrampe

I'm still in the "patently false" camp.

Not according to Quine.

While it may be hard to pronounce, the argument is really a simple syllogism in the form:
If A is B, and B is C, then A is C.
- Replace A with 'all that can exist'
- Replace B with 'anything that we can conceive'
- Replace C with 'anything that must exist' — Samuel Lacrampe

We can clean this up, even without resorting to quantified modal logic, into an actual Barbara like so:

Everything that can exist can be conceived of.
Everything that can be conceived of must exist.
$\therefore$ Everything that can exist must exist.

Remember universals are really conditionals:

If something can exist, then it can be conceived of.
If something can be conceived of, then it must exist.
$\therefore$ If something can exist, then it must exist.

See how the second premise is not what you were trying to use Hume for?

Even S5 only says that anything that is possible is necessarily possible (IIRC), not that anything possible is necessary.

(I think someone, maybe Alvin Plantinga, has argued that if God is possible then he must exist--that his existence in some possible world would be necessary in that world, and that if he's necessary in that possible world then he's necessary in all of them, and therefore he exists. It was something like that.)

I don't know what to say about the event vs. object stuff. Causation between objects--or all this talk about objects having or not having a cause, which even I fell into--it doesn't make any sense to me. I'll stick with events.

we cannot say that 'everything has a cause', only that 'everything that we can observe (the natural universe) has a cause'. — Samuel Lacrampe

Sure, so long as you understand that now you're not saying anything about what's in the natural universe--your predicate is coextensive with it.

But the law of non-contradiction is an absolute. — Samuel Lacrampe

Not what I'm talking about. Bivalence is different. We do not have to accept that "has a cause" is either true or false of entities that are in principle unobservable.

Actually, I don't think that 'everything has a cause'. Only that 'everything in the natural universe has a cause'. There is no need to extend the principle further than the data set that we can observe, which is only the natural universe. — Samuel Lacrampe

You know you just emptied the predicate "has a cause" of all content by extending it to everything, right?

Logically, either a thing has a cause or else it is an eternal being which has always existed, — Samuel Lacrampe

Some of us are going to balk at extending the principle of bivalence to propositions that, as you just told us, are in principle unverifiable. I might.

One more vote against a word-like editor, which they wouldn't do anyway.

This is not the causal relationship between the hammer and the nail. — Samuel Lacrampe

I haven't spent a lot of time thinking about causation, but it seemed most natural to me to describe it as a relation that held between events rather than objects, so there you have me trying to describe a property of an event, which, as I said, is awkward, for me at least.

I still think it makes sense though.

So, you've been at this for over week, how's it going?

There are some things you could try if you get stuck:

• Linguistic ascent: instead of looking at the thing you're interested in, look at how we talk about it.
• Go transcendental: instead of asking, "Is such-and-such the case?" ask what would have to be the case for such-and-such to be the case?
• Theory-crafting: instead of trying to provide an account of something, ask what a theory that could provide such an account would be like, or would have to be like.

Sometimes it will turn out you can answer some question from this list, and you'll learn something important--maybe a new approach, maybe that your original problem cannot possibly be answered, etc.

I was just pestering @Owen for no particular reason.

I'm still not sure what you're up to here. It's starting to look like you're deriving existential generalization in a roundabout way. You don't need to.

$Fa\to\exists xFx$

is already a rule of FOL.

Kind of followed by my understanding of the last line of Owen's post. So perhaps I misunderstood. I'm trying to get a clarification. — noAxioms

I think you followed him okay, but it's not yet clear what he's up to.

Maybe the four-leggedness is not true of unicorns because they would first need to exist to have the four legs, but then the reasoning is circular and meaningless. — noAxioms

Yeah, that's a distinct possibility.

Somehow I missed that you're doing this the other way round. You have the quantifiers ranging over the predicates. Is this deliberately second-order logic or are you just doing it backwards? (Quantifiers can't range over predicates in FOL.)

Where you getting the individuals in this scheme? If you can predicate anything of Descartes, you've already assumed Descartes exists.

If you can prove unicorns exist by saying they have four legs, you know you've done something wrong.

If you're wondering what other way there is to take quantifiers, I think--and I'm no expert--the principal alternative is to take quantifiers as "subsitutional."

Construed substitutionally, $\exists xFx$ says "'$x$ is $F$' is sometimes true, depending on what you substitute for $x$" and $\forall xFx$ says "'$x$ is $F$' is always true, no matter what you substitute for $x$." Quantifiers, on this view, range over expressions, not objects. (Again, no expert.)

It's Quine. He takes the existential quantifier as really talking about existence, in the "ordinary" sense.

So if your system needs a formula such as $\exists x Fx$ then your ontology is committed, as he puts it, to the existence of whatever goes in the $x$ place.

If A caused B, whatever that amounts to and whatever you take as A and B, then B has the property of "being caused by A," but A doesn't. — Srap Tasmaner

Almost forgot--as soon as I wrote that, it occurred to me that anything qualifying as a "greater cause" in the defined sense, would have to be self-caused. Coincidence?

Now if 'all that can exist' is 'anything that we can conceive', and 'anything that we can conceive' is 'anything that must exist', then 'all that can exist' is 'anything that must exist'. (wow that was hard). — Samuel Lacrampe

You're on the verge of reinventing S5.

There is a lot of prior art here, and a lot of disagreement, even controversy, among philosophers on the interpretation of modal logics.

That's okay if you have not heard of God being defined in that way before. You just need to 'buy' into the definition for us to have a meaningful argument; because we cannot argue if we are not on a common ground when it comes to the terms used. We could technically replace the word 'God', with the word 'X', and this would not change the validity of the syllogism, as long as we agree on the meaning of the terms. — Samuel Lacrampe

Cool. I'm glad you see the distinction. What's important is (a) not to assume that what carries the authority of common usage is true, and (b) not to assume every definition, however clear, has some object answering to it.

You could use this as a definition, something like:

We define a "greater cause" to be a cause which possesses all the properties that its correlated effects possess. — Srap Tasmaner

Just nitpicking: Your definition makes the cause 'equal', not necessarily 'greater'. — Samuel Lacrampe

That would be true if I said "all and only," which I didn't.

On the other hand, you could be making the following claim:

No effect has a property not possessed by its cause.

This is patently false, as a moment's reflection would show. — Srap Tasmaner

Can you show me why? — Samuel Lacrampe

If A caused B, whatever that amounts to and whatever you take as A and B, then B has the property of "being caused by A," but A doesn't.

If that seems too clever, here's another: striking the nail with a hammer causes the nail to enter the board. The nail entering the board has the property of wood being displaced by steel; the hammer striking the nail does not. (That's awkward, but I don't really know how to talk about cause and effect perspicuously.)

[As an aside: I did some googling, and it looks like a lot of your ideas come from apologetics. I just want to commend you for coming here to test them out among people with different backgrounds and commitments.]

'Greater' here means that the effect cannot possess a property that was not present in its cause(s). — Samuel Lacrampe

You could use this as a definition, something like:

We define a "greater cause" to be a cause which possesses all the properties that its correlated effects possess.

I'm not sure what use this is, but okay.

On the other hand, you could be making the following claim:

No effect has a property not possessed by its cause.

This is patently false, as a moment's reflection would show.

I don't see how you can say that when you talk about something that you're referring to visual imagery, or a sound, or a feeling, etc. but when it comes to obligations, you aren't? An obligation is one of those things that are composed of many different concepts and sensory impressions - like the feeling you get when you don't uphold your obligations, or the feeling you have when you do, or what that obligation is composed of, like going to work, your co-workers who depend on you, your clients who you've built a nice relationship with, etc. - all of which are composed of visual imagery, etc. — Harry Hindu

This is my starting point:

• Words (like anything else) have associations for you based on your life history and can be quite complex. Some of these associations can be described--i.e., put into words--but some can't, some you're not even (quite) conscious of, and it is inconceivable that you could share the entirety of your associations with someone else. They are in an obvious way private, taken as a whole, even though they may be similar to another's associations because we are broadly similar to each other living broadly similar lives.
• Words have meanings as sentence-parts. These are public, and shared. It is because "red" means what it does in English that your mother taught you to say "red" in the presence of red things rather than something else.
• In between there are connotations, which are shadings of meaning based usually in the history of a word's use within a language community. The use of a particular word in particular sorts of sentences can itself be a source of associations for people, but these associations are inherently public. (Any given member of a language community may or may not be aware of the connotations, depending on whether they are familiar with the history of the word's use, but that history is public.) Racial epithets are the obvious examples.
• Words can be used to refer to objects, taken broadly, and not excluding words themselves. (It is not clear to me that a word or name "has a reference" in the way it "has a meaning"; whether a word is being used to refer seems dependent on its use in an assertion/question/command/etc.)

The "meaning" and "reference" bits there are the least fleshed out because they're the interesting (i.e., hard) bits. What's certain, though, is that the meaning of a word is not whatever associations you have with that word.

Thinking and imagining are composed of sensory impressions. I'm arguing that you cannot think without your thoughts taking some form. Words are simply other visuals and sounds that we associate with other things. We even associate other things that aren't words with other things, like the taste of a cookie with the visual of a cookie, or maybe even your mother who makes the best cookies - associations that one can establish without even knowing a language. — Harry Hindu

I will not pretend to know how thinking, taken broadly, works, or how language use and thinking go together. Just as, above, we were drifting into linguistics, here we drift into psychology. I'll make just a few "points" that seem to apply to much of our thinking and language processing:

• It is incredibly fast. The vast majority of your language production and consumption happens without any pausing to reflect, puzzling out, deducing, etc. Mostly it just works, and works so far as you're concerned instantly.
• Much of it is involuntary. You do not "decide" whether to understand words you hear in a language you know, you just do. You often do not "decide" which words to use when you speak--the intent to communicate something leads directly to the right words without conscious effort.
• And those two points lead directly to the third, which is that a whole lot of language processing (and thinking) is unconscious, quite likely carried out by specialized structures in your brain.

We tend to be aware of the exceptions, trying to find words to express a thought, puzzling out what someone means, etc. With thinking as well, the exceptions, where the incessant flow is interrupted, seem to be where conscious rationality finds room to work.

But that also means that the sort of empiricist view you express here is missing a whole lot of data. I love Hume too, but linguistics and psychology have moved on.

Yes, I believe I experienced my mother before I learned the word "mother." (I don't know why you would think I had claimed otherwise, but no biggie.) — Srap Tasmaner

Of course it's a biggie because it shows that your words refer to other things, and that is what you mean when you say them. I should just drop the microphone here, but I'll indulge you a bit more. — Harry Hindu

You seem to be under the impression that I denied words can be used to refer. As I said before, I don't know how you got that impression, but I hold no such view, and do not believe I have expressed such a view here.

(If you could point out to me what I said that gave you that impression, I would be grateful; perhaps I expressed myself poorly. It happens.)

So, prior to typing something on the screen, you don't have an idea composed of a visual of how things actually are, and then use that idea to come up with words to communicate that idea? Are you seriously saying that the only thing that comes to your mind is words that get typed out on a screen? — Harry Hindu

I'm not aware of having "an idea composed of a visual of how things actually are" before I speak, or write, except when I'm trying to describe something I'm imagining visually. — Srap Tasmaner

Then what are you talking about when you say or write anything about some state-of-affairs that exists? — Harry Hindu

I simply do not understand how these are connected. If I talk about something I am visually imagining, that's what I'm talking about. If I talk about something I'm looking at, I'm not talking about something I'm imagining. I can talk about having an obligation, even though I don't know how to visualize an obligation. I talk about music all the time without ever visualizing it.

I just really have no idea why you would think I have to visualize something in order to talk about it. Maybe I've misunderstood you.

What about what I said about translating words from different languages. What are we translating if not the meaning of the words? — Harry Hindu

If you're suggesting that I think words don't have meanings, I'm once again at a loss, as I don't think I've said anything to suggest I think that.

We use the words we do to form novel assertions (questions, commands, etc.) because of the meanings those words have. — Srap Tasmaner

Wait a second, are you even reading my posts? — Harry Hindu

Yes, of course. It wasn't clear to me what you were saying, so I wanted to focus on one thing at a time, make sure we're talking about the same thing, and then it would be clearer where we agreed and where we disagreed.

Are you agreeing at all with what I said about your mother,

Yes, I believe I experienced my mother before I learned the word "mother." (I don't know why you would think I had claimed otherwise, but no biggie.)

about typing words on screen,

Here I disagree. I'm not aware of having "an idea composed of a visual of how things actually are" before I speak, or write, except when I'm trying to describe something I'm imagining visually.

and all those other questions I asked?

I honestly thought some of them were rhetorical, and I'm still not sure which is which.

Do you think that you are the only one that can ask questions and receive answers? If you expect me to answer questions, you need to do the same.

Fair enough, and in that spirit I have directly answered the questions you mentioned, and I will answer each of the questions in the last paragraph:

What made you say, "I have to be at work by 2:30 today."?

We don't know. There are quite a few possible scenarios. For the record, I would take "what made me say it" as something different from "what I meant by it," which is in turn different from "what the sentence means."

Why are you saying it?

Also don't know, and now we can add "why I said it" to that list. These things are all different to me.

Isn't it because there is a state-of-affairs that needs to happen in the future?

Maybe? That's an odd way to put it. It's also possible that I was lying when I spoke, which would change "why I said it" but not "what it means."

Isn't it a prediction that you are referring to?

I really hadn't thought of that one. It doesn't sound like a prediction to me. I would have assumed most English speakers would hear "I have to be at work by 2:30 today" as expressing an obligation. (For comparison: "I will be at work today by 2:30" I would hear as a prediction, or more likely an expectation.)

[As an aside, and I sincerely hope you don't take offense here, but may I ask if English is your native language? I only ask because I might mistakenly rely on our hearing things the same way, and if we don't there could be needless misunderstanding.]

After all, there could be an accident on the way to work and you could be late. How is it that you could be wrong about being at work by 2:30 that doesn't have to do with how you used your words?

I really don't hear that sentence as a prediction, but if it were then of course it would be vulnerable to going wrong in the usual ways, as you suggest, which don't have to do with how I use words.

So I've answered your questions as best I could. I hope it helps.

[Retracted: @darthbarracuda correctly spotted a risk that his thread would be hijacked. (Sorry, man.)]

Let's look at a specific example.

Suppose I tell you, "I have to be at work by 2:30 today."

Maybe as I say this, there are various images in my mind--flashes of my workplace, the people there, driving, getting ready for work, saying goodbye to the kids. Maybe all of these and a lot more, maybe only some, maybe interspersed with other images and thoughts--I am conscious at the moment and also thinking about other things, taking in my surroundings and so on.

I want to say, just to start with, that none of this stuff going on in my head is the meaning of the sentence "I have to be at work by 2:30 today." I want to distinguish all that stuff from, as you put it, the idea I intend to communicate to you.

Can we agree on that much?

I guess we part company here then. Best of luck to you.

It's almost like in the absence of sensory input or (what usually passes for) conscious thought, you end up eavesdropping on (other parts/systems of) the brain going about its business, and you don't understand what the hell you're listening to.

(Just speculative chit-chat.)

Premise 1: God is traditionally defined as 'that which nothing greater can be conceived'. You can look it up; I did not come up with the definition.
Premise 2: No effect can be greater than its cause(s). This is a principal in causality. If you object, you would need to find an exception to this principal. — Samuel Lacrampe

Premise 1 is a claim about language use among I don't know what community of speakers, which doesn't seem like it would suit what seems to be a metaphysical argument. There's also something there about this community's imaginative capacity, and I don't know what to do with that that either. I don't know how to verify any of those claims, or what I would have if I did. Even if Premise 1 is true in some specified sense, what good is it?

I don't have the faintest idea what Premise 2 means. I guess that's on me. What does "greater" mean here? That would help. I'm not even sure what kind of statement it's supposed to be. Is it a natural law, or some sort of metaphysical law?

Whatever sort of statement Premise 2 turns out to be, it seems like a different kettle of fish from Premise 1, so I don't see how they're supposed to be linked.

I do not feel contradiction with apokrisis - I view my dreams differently and told him it was his prerogative to see it his way. There can be more than many truths. I really believe it is entirely subjective. There is no grand formula for interpretation and meaning. The value and purpose we place on dreams is totally subjective. Dreams mean what you think they mean – don’t let anyone tell you otherwise. — woodart

In a sense, that's saying there's just nothing for philosophy to do here, and that's fine.

But maybe there is some stuff to get into here. Our non-dream experiences include a bodily component that others can (at least in principle) witness. And our bodies are not so dramatically different from each other that when we talk about those sorts of everyday experiences, we can assume a lot of that experience is similar. Often when someone says, "I know how you feel," that can be literally true.

Dreams, though, seem to be a unique class of experience. Even though our minds are broadly similar, just as our bodies are, the whole range of physical correlatives is missing. You get mentation naked, so to speak, and that seems like something philosophy, as well as psychology, would want a look at. Only you can't have that. All you get is people's reports.

Even if dreams were uniquely subjective, how could we know?

Where do you see a flaw in the logic? — Samuel Lacrampe

I guess if I had to pick something, I'd say, "All of the premises and inferences."

we deduce — Samuel Lacrampe

No we don't.

People find meaning and value in all sorts of experiences, whatever their source.

You don't have to see what @apokrisis said as contradicting your view. Your brain does stuff; you experience that in a certain way. What the brain does has side effects; you experience that too. There may be a "physiological purpose" of some kind to what goes on while you sleep; I think some researchers have also suggested it's the brain finishing processing the day, so that's a more "cognitive purpose," more directly related to your experience. Whatever it's doing can be a real and meaningful experience for you, especially since what it has to work with is mostly your life.

I do wonder how we could possibly resolve a conflict about the nature and meaning of dreams. Philosophers have had a hard enough time dealing with "intuitions." One place to start might be taking a closer look at what I casually described as "experiencing" your dreams. It's clearly way different from other sorts of experience we have.