Would a falling tree still make a noise if no one was around to hear it?
Yes. — Qurious

It would make sound waves, but if there are no ears around, then there would be no sound as a phenomena. This is where it gets tricky. Does the tree look brown and green? Well, it does given the sort of eyes we have. But what about when nobody's looking? Well then it's reflecting light with wavelengths that correspond to brown and green perceptions, in addition to any light humans can't see that would be reflected by a tree. There's also all the light that passes through objects like trees, such as radio waves.

It makes you wonder what the sky would look like if our eyes could take in the entire EM spectrum.

Is metaphysical realism equivalent to belief in objective reality, or is there something more to it? — T Clark

I would have said that, but then skeptical scenarios like the Matrix would qualify. I think Michael put it better:

Metaphysical realism also seems to require that the kinds and categories that the things in experience belong to are also the kinds and categories that those mind-independent things belong to, but I think there's a case to argue that this isn't the case. — Michael

How similar does reality need to be for metaphysical realism to be true? Does the fact that tables are mostly empty space mean that solid tables don't exist? Or can we just say that within the light we see, and given that our bodies and ordinary objects are held together molecular in a similar fashion, tables are solid?

Or what if we take Banno's approach to objects, and say that there are different ways to carve up the world? Can there be a multiplicity of conceptual schemas about the world, but the world is still real?

The philosophical error here is to mistake a question of grammar for a question of ontology. — Banno

So basically, we can carve up the world anyway that makes sense, but asking whether our carving exists is to mistake carving for ontology.

What counts as a simple is utterly dependent on what we are saying.

The rest of this thread is confusion. — Banno

Many things we consider to be objects are made up out of parts. The question is whether something made up out of parts can be singular. I think of myself as a single animal, a person, a mind, etc. But I'm made up of tons of cells. And those cells are made up of molecules, and so on.

Are people, rocks, stars actually objects or do we mistakenly think they are?

Since this is an ontological question, the concern is with what really is, not how we conceive of people, rocks, stars.

But we only ever experience our experience, ie the model. — Agustino

What does it mean to experience our experience? Isn't that how we get in these philosophical muddles in the first place? Do I experience the tree, or do I experience the experience of the tree?

Yet the abstract mind can see the ultimate futility of all plans. There is no future, or (apparently) no stable and ultimate future. So our best laid plans are haunted by absurdity. — ff0

Vanity of vanities, says the Preacher, vanity of vanities! All is vanity.
What does man gain by all the toil at which he toils under the sun? — Ecclesiastes

I was on vacation, and I realized it would quickly pass and I would never get to do the vacation over again. That was a bit depressing.

Not everything has to be of practical importance to be worth doing. Humans watch and debate sports, movies, read comic books, they go to art galleries and concerts, etc.

Not all science has a practical effect on our lives. It really doesn't matter if there is massive black hole at the center of the Andromeda Galaxy. But it's interesting.

That's why I cringe whenever the argument comes up that science exists for technology's sake. No, science, like philosophy, exists first and foremost because we're a curious species. We like to ask questions. We want to understand. We're puzzled by the world and ourselves.

This narrow prejudice ignores the fact that as embodied we feel the forces involves in causal efficacy; we feel ourselves being pulled, pushed, impacted and generally acted upon by natural forces in phenomena such as sunlight, wind and water, and also we experience pulling, pushing, impacting and generally acting upon other things. The bodily feeling of these forces is the source of the concept of force which distinguishes causation from mere impotent correlation. — Janus

Good point. Perception in philosophy is so often focused on vision that I wonder if it doesn't sometimes lead philosophers astray. If we're the billiard balls feeling the strike as we move in response, does Hume still make the claim that we don't perceive causation?

To doubt, you need a reason to doubt, not just a contextless wondering whether things might be different than you think they are. — gurugeorge

Right, so for example you can imagine this is all a dream, but then we understand the distinction between dreaming and waking because we spend part of our time awake. But what does it mean if we were only dreaming the entire time?

Just like we can imagine taking a brain and putting it in a vat, but what would it actually mean for us to be brains in vats?

I understand what a simulation is because of the real things it's simulating, but what if everything was simulated? Then what does "simulated" mean?

See the Sime & Willow posts above my response. Also see other posts in this thread talking about habit or passion, including yours.

What Hume was puzzled by was how we came to have a concept of causality since it's neither empirical nor a logical deduction. I've been arguing that habit in response to constant conjunction is not enough to arrive at the concept of causality.

Beyond that, I think very few people actually have world views that you would consider "realist." In the US, something like 45% of adults do not believe in evolution. More than 80% believe in God. — T Clark

That doesn't make you non-realist. That just means you think reality is different than the naturalistic version. Metaphysical realist means a belief in a mind-independent world. I grew up Christian, and most of those folks believed God created a material world that may or may not be compatible with what scientists say. I don't recall anyone espousing Berkeley's idealism, other than reference to Christian Science or gnosticism, which was considered heretical.

The point is that we do have the concepts of necessity and causality, contrary to what the Humeans in this thread have been arguing.

It's not that we can't be wrong about what's actually necessary/causal, only that we can and do conceive of such things. Kant was right that causality is fundamental to our thinking.

Hence to say that "B necessarily follows A" is in some sense compatible with saying "B doesn't necessarily follow A". — sime

The laws of thermodynamics prohibit perpetual motion machines from being invented.

Nothing with mass can be accelerated to the speed of light.

It's impossible to know both the position and momentum of a particle with 100% certainty.

You can't build a storage device consisting of a sphere of 6.7 cm or smaller containing more than 2.6 X 10^42 bits.

You can't build a computer that carries out more than 5 X 10^50 operations per second.

You can't transmit information faster than the speed of light.

You can't perform a measurement below the Plank scale.

You can't have a temperature below 0 degrees Kelvin.

All of the above and more is necessarily the case without exception.

Presumably not so much for someone who actually believes it. — Wayfarer

That would be called faith, not a fact, would it not? Or even imagination, if we moved God from heart to head, depending on the person in question.

Do you expect an answer? I don't know. I don't know what you mean. — T Clark

That's one problem with God being a fact.

That's definitely a metaphysical question. — T Clark

God exists in my heart. True or false?

Hume says we are creatures of passion primarily not rationality; don't expect him to derive shit, he's busy pointing out how underivable it is. — unenlightened

That still fails to explain how we came up with the concept of causality. Saying that it's a habit of mind is not explaining how the concept could form.

And since Hume was an empiricist, he has nowhere else to go.

There is a passion to find a pattern, a passion to predict. — unenlightened

A passion isn't a concept. We have a concept of causality. Hume wasn't able to provide a good explanation for how we arrived at such a concept.

As has been noted earlier in this thread (in correction to something I posted), correlation isn't causation. So you can't derive the concept of causation from constant conjunction.

But the way it is interpreted has considerable metaphysical implications. I have no doubt at all about the facts of the matter, but considerable doubts about what they are taken to mean. — Wayfarer

You and me baby ain't nothing but mammals?

Darwin's theory of evolution by natural selection is not metaphysics. Evolution is a fact in the world. The theory that natural selection is the primary mechanism of evolution is well supported by factual evidence and is believed by a consensus of those with a strong understanding of human biology, geology, and paleontology. — T Clark

Right, but science has taken over for metaphysics in the past on questions that can be empirically investigated. At one point, the idea of evolution was metaphysical. That was before Darwin, of course. Same with atomism.

I don't understand what passion has to do with causality.

As I've said many times on many threads and I will say many times more - metaphysical systems, of which science is one, are not right or wrong, there are more or less useful in particular situations. — T Clark

Do you think any other metaphysical system has a more useful answer than evolution as to how humans came to exist?

Actually, I'm not that interested in useful since a creationist can easily argue that their faith about creation is useful to them. Do you think anymetaphysics than science (really naturalism) has a more true answer?

I don't think what I have asked for is certainty at all. All I have asked for is that the Realist have some account, which he can at least convince himself is true, of how human beings can have any reliable basis at all for the belief that Realism is true. — PossibleAaran

Wouldn't realism being the most likely inference from experience qualify? We don't need to posit demons or computer simulations. We can just say the things in perception continue to exist while not being perceived, along with other things we can't perceive, but we can infer from things perceived, like elementary particles.

That goes well with science, which doesn't infer demons or simulations or brains in vats, but does infer plenty of unobservables that make good sense of what is observed, along with object permanence.

whatever it is, sounds good to eat. — Wayfarer

It does. Certainly better than the tofu-turkey I had recently.

Also, someone made a shrimp-eating addendum to Stove's worst argument. So if anyone manages to eat a trout-turkey, then we can be sure it exists.

I rather like the idea of doing philosophy through eating. Vision has been abused for centuries. Time to take a culinary turn.

That's a good answer, and some philosophers are committed to living things being an exception. Living things can have parts.

Seems to me the same argument can be made for machines.

The problem with things like rocks is we can easily get into sorites issues. How many mineral parts are needed to make a rock? Is it the same rock after it's been weathered? If you have a bunch of rocks piled together, do they form a rock heap? What's the fundamental difference between a heap of rocks, and the rock minerals inside a rock?

Are these "priors" not temporally prior? If the "prior" is necessary for the existence of the thing, then isn't the prior necessarily temporally prior to the existence of the thing — Metaphysician Undercover

Right, but it's not the the temporal priority that is sufficient, it's the nature of the prior. If the universe was filled only with inert gasses, then their prior existence would not lead to any chemistry.

So Kant wouldn't have said anything to a hand waving argument either?

Neither would Wittgenstein, but for a different reason.

If you analyze "logical priority" you will see that the only valid way that something can be prior to another is that it is temporally prior. — Metaphysician Undercover

Some things can't come to exist without the priors. Babies exist because of mothers. Life exists because of chemistry. Chemistry exists because of physics. In fact, chemistry has a close mathematical relationship to physics. The physics of atoms dictate that molecules will form under the right conditions.

Are you saying that our experiences are objective? I'm not even sure what that means. I would have thought that personal experiences are the essence of subjectivity. — T Clark

Some of our experiences are subjective, but it's not clear how perception should be classified.

Which is begging the question. Who says being in the world is primary (other than Heidegger)? — T Clark

Heidegger makes the argument that we're always actively doing things with goals in mind which make sense in terms of a world, and it's only by abstracting from those activities that you can put yourself in a position to have radical doubt, which is an act of forgetting your constant worldly activity.

Or something along those lines, as I understand it.

Since we can't step outside of our perceptions, there's no reason to supposed we're inside an objective reality. It's merely a philosophical exercise in what sort of wild scenarios we can imagine which aren't incompatible with our experiences. — T Clark

A Heideggerian critique of that might be that our being in the world is primary, and so abstracting away from that to ask radically skeptical questions about our perceptions of the world is to make a fundamental mistake.

You're asking this question by starting out saying objective reality exists. We're not in a situation were we can do that. We can only imagine the possibility. — T Clark

This is assuming that our perceptions are subjective, and thus there is an objective gap that needs to be crossed to get at an external world, if it exists.

But one might start over by rejecting the notion that perceptions are subjective, or at least deny that perceptions make us aware of subjective objects (sense datum).

I think you are a victim of a failure of imagination. It is a common intellectual malady to believe that words and the world are the same thing. — T Clark

I can understand the brain in a vat argument. But I'm not sure that's the same as being in the world. Maybe we're just imagining that an envatted experience could be indistinguishable from an embodied one, because we don't know enough to rule it out.

I studied Hume under David Stove. He was a great guy, and a terrific teacher. Very sympathetic to me, who was kind of a rebel without a clue. But I don't think Stove 'got' Kant at all. — Wayfarer

Really? That's interesting. What would be Kant's response to Stove's worst argument critique?

think what the realist does, and this is something Schopenhauer is explicit about, is that s/he forgets to take account of him or herself, the sense in which all of our knowledge of the world is mediated by the senses, assimilated by the understanding, and represented in the intellect. Realism, generally, doesn't critically reflect on the nature of experience, and the contribution the mind makes to it. — Wayfarer

Also known as Stove's worst argument?

But as far as I can see "synthetic a priori judgements" are just a long-winded way of saying "sentiments". — unenlightened

But since Hume was an empiricist, isn't he ceding ground to rationalism here by saying we have a sentiment toward causality? He's admitted there's something fundamental in our thought processes which we use to make sense of the world that doesn't come from sensory experience.

You can't get a will-be from a was, any more than you can get an ought from an is. The gaps are bridged by habit and sentiment. — unenlightened

I don't buy the argument that the gaps are bridged by habit and sentiment anymore than Kant did, even though unlike Kant, I think causality is real.

It's just obvious to me that we inhabit a causal universe, otherwise there would be no reason for it to have such a deep, uniform order to it over billions of years.

For just as we cannot rationally infer causation, we cannot rationally infer correlation. — sime

The problem is that we do both all the time. Our technology and science is based on being able to make predictions from what we consider to be correlation or causation.

It's not just that we observe past Bs following As, it's that we infer C will follow B given AB. If we know that all objects fall to the Earth at 9.81 m/s, then we can propel something into outer space with an acceleration greater than 9.81 m/s. Then given other Bs following As in chemistry, we can create the fuel to make this propulsion work. And so forth to the point that we can land spacecraft on other planets we've never been to.

That's why it's hard to take Humean skepticism seriously outside of a philosophy discussion.

Strange as Idealism is, we never found any reason to think that things exist unperceived. — PossibleAaran

What do you mean by never having found any reason? Do you mean any reason the idealist would accept? I think there are good reasons for being a realist. They might not be good enough to convince an idealist or skeptic, but that's their problem.

Interesting. So objects on the Earth cannot but be pulled at the rate of 9.81 m/s, because that is simultaneous with the Earth's gravitational field.

what was the tradition understanding?

As a realist, I would say that if we observe constant conjunction, we're observing causality. But we often have to infer the nature of it, and it's always possible to infer incorrectly or incompletely. Something is causing everything to fall to the Earth at a rate of 9.81 m/s, otherwise why would a cannon ball fall at the same rate as a feather, once you factor out air resistance? That's totally unexpected.

Oh, it might be because causality really is a thing out there in the world, hmmm, I see... — Agustino

Might just be.

If I were to take the Idealist route, I would likely answer you like this. The Idealist view is not that nothing exists unperceived by me, but that nothing exists unperceived by some mind. The starving kids in Africa obviously perceive themselves and their starvation, so the Idealist need not say they don't exist. The same with terrorists. The rain forest being cut down is obviously being perceived by the people cutting it down. — PossibleAaran

Sure, but the idealist knows about other perceivers the same way they know about laptops. I see you. I close my eyes and then open them. I see another you.

The rain forest being cut down is obviously being perceived by the people cutting it down. — PossibleAaran

I don't really understand caring about a rainforest that only exists as perception.