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"A priori" in the scientific vs. philosophic case?

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Please give me an argument from "existence exists" to some sort of conclusion on whether the universe is expanding.

Personally I'll go with the simple observation of the red shifts of distant galaxies to reach the conclusion on this, but please give me the a priori rational argument here.  Please include detailed steps, as I seem to be confused.

'A priori' is Kantian nonsense; there is no possible knowledge before experience.

Edited by softwareNerd

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'A priori' is Kantian nonsense; there is no possible knowledge before experience.

The fact is statements about things like infinite/finite space, beginning the universe, nature of the universe, are questions of a scientific nature and shouldn't be addressed without an appeal to empirical evidence. Any analysis which doesn't address empirical scientific data is worthless.

Also the terms "a priori" and "a posteriori" are perfectly valid philosophical terms predating Kant. You should do some research.

Edited by softwareNerd

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Also the terms "a priori" and "a posteriori" are perfectly valid philosophical terms predating Kant.  You should do some research.

Valid to whom?

Not to Objectivists. Objectivism rejects this as a false dichotomy. As already said by N_T

there is no possible knowledge before (apart from) experience.

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a posteriori refers to something that has been directly empirically observed

a priori refers to something which is inferred without direct empirical observation

There is a difference between a priori/a posteriori STATEMENTS and a priori/a posteriori KNOWLEDGE.

Let's take a somewhat contrived hypothetical situation:

Imagine a chemist friend of yous synthesizes a new substance and hands you a ping pong sized ball of it. You have a chamber which produces a vaccuum and is able to shield its interior from electro-magnetic fields. You ask yourself "How fast will this ball of stuff fall if I drop it in there?" A resonable conclusion is 9.8 m/s^2 as this has been observed to be the acceleration of freely falling objects in the Earth's magnetic field. This is a very well-tested result with a lot of theoretical backing. If you ask physicists most will be quite confident that is what you will see. However since this is a new substance, it has never had its free fall acceleration measured. Thus at this point the statement that it will fall at 9.8 m/s^2 is still *A PRIORI* since it has never been empirically observed, even though the statement is based on much empirical data of other falling substances. Once we drop the ball and measure it the result is now *A POSTERIORI*.

You can see that the vast majority of our reasoning is a priori in nature as we assume things will happen without having empirically observed. This is why we are wrong so often.

This is the basic pre-Kantian usage.

When getting into Kant the issue is a priori/a posteriori KNOWLEDGE, which requires an appeal to CERTAINTY the truth or falsehood of the statements that for by far the majority of statements would require some godlike omniscience.

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a posteriori refers to something that has been directly empirically observed

a priori refers to something which is inferred without direct empirical observation

There is a difference between a priori/a posteriori STATEMENTS and a priori/a posteriori KNOWLEDGE.

In "For the New Intellectual" Rand describes: "those who claimed that man obtains his knowledge of the world by deducing it exclusively from concepts, which come from inside his head and are not derived from the perception of physical facts (the Rationalists)---and those who claimed that man obtains his knowledge from experience, which was held to mean: by direct perception of immediate facts, with no recourse to concepts (the Empiricists)."

Which makes me think there is still an error here where you are divorcing statements from the concept or knowledge they represent.

Because Objectivism is based on axioms and this is an example (as I understand) of your own failure to grasp the axioms. Similar to the issue with existence exists that was brought up earlier. (trying to stay on topic)

I would say what you mean by an a priori statement is actually a theorum.

I'm getting a little over my head here though, so perhaps someone else can jump in?

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In "For the New Intellectual" Rand describes: "those who claimed that man obtains his knowledge of the world by deducing it exclusively from concepts, which come from inside his head and are not derived from the perception of physical facts (the Rationalists)---and those who claimed that man obtains his knowledge from experience, which was held to mean: by direct perception of immediate facts, with no recourse to concepts (the Empiricists)."

Which makes me think there is still an error here where you are divorcing statements  from the concept or knowledge they represent.

Because Objectivism is based on axioms and this is an example (as I understand) of your own failure to grasp the axioms. Similar to the issue with existence exists that was brought up earlier. (trying to stay on topic)

I would say what you mean by an a priori statement is actually a theorum.

I'm getting a little over my head here though, so perhaps someone else can jump in?

This is getting dangerously close to merely quibbling over the definition of words rather than getting to the underlying issue.

Most people try to use "knowledge" in a way so that one cannot say "I know that A" if A isn't true. However most scientific hypotheses are wrong, so we wouldn't call them "knowledge". However they are still meaningful, so we need a broader term to include what falls under "knowledge" as well as things as hypotheses that can be wrong. I used "statement" if you want a different term for this, use it. But let's not debate the terms to use.

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This is getting dangerously close to merely quibbling over the definition of words rather than getting to the underlying issue.

Most people try to use "knowledge" in a way so that one cannot say "I know that A" if A isn't true.  However most scientific hypotheses are wrong, so we wouldn't call them "knowledge".  However they are still meaningful, so we need a broader term to include what falls under "knowledge" as well as things as hypotheses that can be wrong.  I used "statement" if you want a different term for this, use it.  But let's not debate the terms to use.

In this case I'll have to come back. I'm not clear on all the issues here, but you've given me something to think on and I'll come back when I understand it better myself.

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Ok, actually, I've got my OPAR out now, let's see if I can use it.

On pg 148 Peikoff states: "This is the cause that explains the popularity of the notion that an idea may be "good in theory but not in practice"

[...] The theory-practice dichotomy is itself a theory; it's source is a breach between concepts and percepts. Given such a breach, thought comes to be viewed as pertaining to one world (the world of Platonic forms, or of Kantian "phenomena", or of linguistic constructs), while action is viewed as pertaining to an opposite world (the world of concretes, or things-in-themselves, or of empirical data). In this set up, one expects to be schizophrenic. [...]"

Ok, so I interpret that to mean that there is still a flaw in your distinction, which is the root of the contradiction you (punk) are holding.

I am still trying to process this myself, so the more specific you and others can be the better (am I off-topic? If so please split the thread Felipe-I'd like to continue discussing).

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punk's definitions of "a priori" and "a posteriori" are a good starting point:

a posteriori refers to something that has been directly empirically observed

a priori refers to something which is inferred without direct empirical observation

This discussion arose from a thread about Physics, space etc.. Just in case there is any misunderstanding, I'd like to clarify that Objectivism does not hold "Existence Exists" to be "a priori" knowledge. [One might -- very loosely -- say that Objectivism holds that all knowledge is "a posteriori". More precisely, since Objectivism rejects the existence of "a priori" knowledge, the concepts to distinguish between the two types are rendered useless.]

In the previous thread, Felipe made the following point.

... there can be no valid theory supported by scientific data which contradicts existence exists...

This is sometimes misunderstood to imply that "Existence Exists" is an "a priori" proposition. It does not. According to Objectivist epistemology, axioms are not "a priori" knowledge.

Punk, while I think your definitions of the terms work, I think your example does not. You give an example of a prediction. Your example assumes that the prediction is based on previous empirical observations. The example seems to imply a proposition such as: all predictions are "a priori".

This is not how many philosophy books and professors would describe "a priori". Most would describe "a priori" and knowledge that is "obvious" in one of the following senses:

- obvious from the way the terms have been defined ("a cube has six sides")

- obvious from the premises ("seven plus five equals twelve")

Here is a brief article. Not Objectivist, but a summary of popular usage of the terms.

It's not an issue of "quibbling over the definition of words" but rather quibbling over their meaning.

I think the best way for someone who would like to play "devil's advocate" to the Objectivist position would be to point to an example of knowledge that is truly "prior to experience". The example does not do that, the prediction about how fast a ball will fall is based on a lot of empirical evidence.

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I would say what you mean by an a priori statement is actually a theorum.

I'm getting a little over my head here though, so perhaps someone else can jump in?

Gladly: It's a theorem. :P

softwareNerd is right, too, when he calls that specific example a prediction; in fact, that was my first reaction to it as well. "Theorem" is more general, though; it covers more of the kinds of other examples that punk might come up with.

So you win again! :D

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Gladly: It's a theorem. :D

softwareNerd is right, too, when he calls that specific example a prediction; in fact, that was my first reaction to it as well. "Theorem" is more general, though; it covers more of the kinds of other examples that punk might come up with.

So you win again! :D

Thanks CF :D

What would I do without you? :P

One more question though-am I correct in saying that Objectivism rejects the notion of a priori anything-and altogether? So in other words it is never an appropriate term?

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A priori knowledge is knowledge you acquire without applying any actual means of acquiring knowledge. The use of the concept implies that knowledge, to be acquired, does not have to actually be acquired. In shorter form, it's the statement that A is not A. It is never a valid concept.

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However most scientific hypotheses are wrong, so we wouldn't call them "knowledge".  However they are still meaningful, so we need a broader term to include what falls under "knowledge" as well as things as hypotheses that can be wrong.

My knowledge is composed of what I know.

The only way to know something is for it to be proven to you.

Hypotheses are educated guesses that you attempt to prove.

It is because hypotheses are unproven, that they do not qualify as knowledge.

[...]

Also, why would I integrate something that is wrong into my knowledge? Doing this can never lead to good.

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A priori knowledge is knowledge you acquire without applying any actual means of acquiring knowledge. The use of the concept implies that knowledge, to be acquired, does not have to actually be acquired. In shorter form, it's the statement that A is not A. It is never a valid concept.

Ok, thank you, that's what I thought but I wanted to make sure.

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Also the terms "a priori" and "a posteriori" are perfectly valid philosophical terms predating Kant.  You should do some research.

[P]unk, terms are neither valid nor invalid. Terms are labels for ideas, and it is ideas that are either valid or invalid, that is, either drawn logically from the facts of reality -- and from nowhere else -- or not drawn logically from the facts of reality.

Of course, if you are trying to say that some ideas about present events are deducible from or predictible from principles developed earlier (and traceable back to sense-perception), then of course you would be right. But if that is your purpose, why not say so? Why adopt the ruinous package of Kantian terms and ideas? Unless of course, you are trying to chip away at Objectivism.

In your post 4, yesterday, you said: "a priori refers to something which is inferred without direct empirical observation."

Why say "empirical"? Are you once again insinuating a ruinous dichotomy into the discussion -- in this case, the dichotomy of rationalism and empiricism? I wonder if you are, because you add nothing by saying "empirical" that you haven't already said with "direct ... observation" or even more simply, "observation."

Speaking of research, please name an example of a pre-Kant philosopher's use of the term a priori naming a "perfectly valid" idea. Then please sketch how that philosopher validated his "a priori" ideas -- that is, took them back to sense-perception.

On the other hand, are you trying -- in your usual manner -- to say that some philosophers before Kant used the words a priori and a posteriori? I haven't made any special study of that, but secondary sources I have read certainly confirm it. As I understand it, a priori was sometimes used to describe syllogisms that inferred (or "demonstrated") effects from causes, and a posteriori described syllogisms that inferred causes from effects. That is interesting information in the anatomy of argumentation, but what does it matter unless all ideas are traceable back to sense-perception?

[Edited to correctly identify past posts.]

Edited by BurgessLau

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The terms "a priori" and "a posterior" should be traced back to the literal Latin meanings.

Let's say something is going to happen (call it "event A", it could be dropping a ball, mixing two chemicals, etc.). Literally "a priori" is just something like "from before", and "a posteriori" is something like "from after", or "prior to" and "posterior to".

A priori refers to everything we state will be true of event A prior to it happening. A posteriori refers to everything we state is true of event A after observing it happen. It is perfectly fine to use "a priori" to be equivalent to simply predictions. But in the case of my holding a ball in my hand and letting go, to take the statement "the ball will fall to the floor" as a prediction seems a little weird as we tend to use "prediction" as a statement of what will happen when there is a relatively higher amount of uncertainty. In this case the statement "the ball will fall to the floor" seems more certain so to call it a "prediction" a bit odd, but its just a choice of how to use words.

Again the issue with Kant is one of "a priori knowledge", the key being KNOWLEDGE. "A priori" can be used find in a sentence like "What can you say a priori will happen when I let go of the ball." without invoking Kantian overtones.

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"A priori" can be used find in a sentence like "What can you say a priori will happen when I let go of the ball." without invoking Kantian overtones.

I’m afraid you’ve got the wrong end of the stick here Punk. The terms a priori and a posteriori refer to ways of knowing, while analytic and synthetic refer to statements. Thus, “all circles are round” is an analytic statement, in that it’s true by reference to the terms used, and it’s known or justified a priori, that is, independently of experience of the external world.

The statement "What can you say a priori will happen when I let go of the ball" is meaningless, since a priori has nothing to do with prediction. The statement "the ball will fall to the floor" is of course a synthetic statement, and its truth is known a posteriori. It’s a synthetic statement because its truth is determined by the way the world works, and it’s known a posteriori because its truth is known or justified by appeal to experience of that world.

Where I think you’re going wrong is in assigning a temporal or chronological priority to the term a priori, when the priority is in fact a logical one.

Eddie

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Eddie is correct. In any case, your knowledge of what would happen when you let go of the ball would be a posterior since it is derived via induction from your experiences of similar objects acting under the influence of gravity. A newly born baby would have no more reason to believe that a dropped ball would fall to the ground than he would to believe it would float up towards the sky and explode.

Edited by Hal

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Is it possible to know that A is A, a priori?  Seems to me that doesn't require any experience.

“A is A” certainly appears to be an analytic statement that is known or justified a priori. As long as we understand the meanings of the terms involved, there is no need to appeal to experience of the world to justify the truth of the statement.

Eddie

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As long as we understand the meanings of the terms involved, there is no need to appeal to experience of the world to justify the truth of the statement.

But, how can we know the meanings of terms -- how can we even form terms -- without experience? Before we say "A is A", surely we must say "A". How can we do that without experience?

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But, how can we know the meanings of terms -- how can we even form terms -- without experience? Before we say "A is A", surely we must say "A". How can we do that without experience?

Sure, we need experience in order to have knowledge, including the meanings of terms. That’s why I said “experience of that world”, as a way of clarifying my use of the term experience in relation to a posteriori knowledge. More importantly, my comment wasn’t just about knowing the meanings of terms. It was primarily about justifying the truth of statements. The two are separate issues.

Using the example of “A is A”, we certainly need experience to know the term “A”. But just knowing “A” is not sufficient to justify the truth of the statement “A is A”. In order to do that, we must apply our understanding to the relevant terms “A” and “is”. “Is” in this case means “is identical to”, or "the same as", so “A is A” means something like “A is identical with itself”. We don’t need to appeal to experience to justify the truth of that statement.

In the case of “the ball will fall to the floor”, just knowing the meaning of the relevant terms is insufficient to justify the truth of the statement. To do that, we need to observe the actions of a real ball. In that case, the statement will be justified by experience.

Eddie

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"A is A" is an application of the law of identity. Once that is proven, then the application is proven as well.

The law of identity is obviously depedent on experience. In order to understand identity, you must be able to be aware of an entity.

In a Kantian sense (one of them anyway, he uses many contradictory definitions), the only things that qualify as "A priori" are things that someone born into a sensory deprivation chamber would know. And I think it is pretty clear that such a person couldn't even be referred to as conscious.

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I'm reading the Critique of Pure Reason now and I'm also dabbling in Objectivism -- I'm good friends with a knowledgable Objectivist and learning a lot from our discussions, and I've read several ARI articles, Objectivism synopses, and have slated ItOE as the next book I will read :thumbsup: . I want to study Kant's and Rand's philosophies comparatively. I have an idea on a priori, a posteriori knowledge re: the metaphysical views of both philosophers that I'd appreciate other's views on.

For Kant, a priori knowledge (analytic knowledge) was knowledge inexorably tied to the nature of reason or mind itself, e.g. concepts like time, space, which are conditions of perception imposed on us by our own minds.

I'm familiar with the Randian dismissal of Kant's Analytic/Synthetic dualistic approach to viewing knowledge in this manner. And I'm familiar with her approach which denied that human perception impinged on our ability to perceive things in themselves, absolutely, i.e. her theory of concepts.

I realize that to adopt Kant's view lands you on a slippery metaphysical slope. Kant's philosophy attempted a dissection of reason itself and the difficulty in avoiding a logical ouroboros in any serious examination of reason here is clear.

Still, I find it presently impossible to deny with certainty that perception is not colored by a prior, analytic truth. The brain is a physical, ordered structure that demonstrably imposes itself on our perceptions -- from our perceptions regarding the speed at which time passes to inferring distance and 3 spatial dimensions via the 2-dimensional patterns of light that strike our retinas. With Kant, a comprehensive understanding of the human brain and its functioning may one day dissolve his dichotomy and make deeper inquiry into what he labeled a priori or analytic knowledge possible.

The Randian avoidance of Kant's aforementioned distinction, vis-a-vis denying that perception at least MAY be affected by the brain, seems irrational and maybe a facile way of stepping over an important metaphysical issue. It troubles me as a new student of Objectivism.

I'd appreciate any comments. Thanks!

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