I'm not checking, but I think of there being two different arguments: one is about whether we can genuinely infer causation by induction from (so far) constant conjunction; the other is about the status of induction itself. I think Hume ends up giving more or less the same answer to both. I'm not sure what to think about causation, but I always found the argument that induction cannot be rationally grounded persuasive.

Yes, I think both the sceptical argument and his sceptical solution are both valid and sound. In fact, I think this is one of only a handful of knockdown arguments you will find in the history of philosophy.

Conclusion: it's not possible for us to gain or obtain knowledge about anything that goes beyond our senses, memory and testimony. — Humelover

Or is it?...

But here it may be proper to remark, that though our conclusions from experience carry us beyond our memory and senses, and assure us of matters of fact which happened in the most distant places and most remote ages, yet [...]

In a word, if we proceed not upon some fact, present to the memory or senses, our reasonings would be merely hypothetical; and however the particular links might be connected with each other, the whole chain of inferences :wink: would have nothing to support it, nor could we ever, by its means, arrive at the knowledge of any real existence. — Hume, Enquiry, section 37

Had not the presence of an object, instantly excited the idea of those objects, commonly conjoined with it, all our knowledge must have been limited to the narrow sphere of our memory and senses; — 44

Hence likewise the benefit of that experience, acquired by long life and a variety of business and company, in order to instruct us in the principles of human nature, and regulate our future conduct, as well as speculation. By means of this guide, we mount up to the knowledge of men’s inclinations and motives, from their actions, expressions, and even gestures; and again descend to the interpretation of their actions from our knowledge of their motives and inclinations. — 65

(My emphasis.)

5. You can't get knowledge of things that are empirical unobserved — Humelover

I wonder how much Plato's Theaetetus had to do with this powerful argument. The key to understanding seems to be recognize equivocation in both arguments on which kind of knowledge we are talking about.

.

..

What do you think? — Humelover

“...It must certainly be allowed, that nature has kept us at a great distance from all her secrets, and has afforded us only the knowledge of a few superficial qualities of objects; while she conceals from us those powers and principles on which the influence of those objects entirely depends....”
(E.C.H.U., 4. 2., 1739, in 2ed, 1777; 1963 ed. sec. 29)

“...Reason must approach nature with the view, indeed, of receiving information from it, not, however, in the character of a pupil, who listens to all that his master chooses to tell him, but in that of a judge, who compels the witnesses to reply to those questions which he himself thinks fit to propose....”
(CPR, Bxiii, in Kemp Smith, 1929)

So.....valid or sound skeptical arguments? From his perspective, it may be either or both. With the premises from which the argument ensues, his conclusions follow logically. But that’s not really what should be asked, given the professed notion that reason and thought in general is not to be considered of greater import than experience, with which the empiricist philosophy of the day concerned itself. If reason and thought are given more substantial influence, experience must release some of its influence, which indicates Hume’s initial premises, while not exactly false, where at the very least, incomplete, as they are predicated on insufficiently explanatory conditions.

Hume wasn’t so much wrong as uninformed. And he was uninformed because, as a philosopher, he didn’t allow himself to think deeply enough to recognize the power reason actually has, a priori. In effect, he didn’t inform himself. He came so close, in the affirmative, in his argument on the missing shade of blue, which he professed a mind enabled to supply, yet in the negative, failed to recognize that same principle with respect to arguments in, e.g., geometry, insofar as he professed the mind has no power to arrive at the sum of interior angles synthetically. Which is exactly how the mind, or pure reason, supplies the missing shade.

Hume’s philosophy wasn’t so much refuted, as it was expanded.

Okay, let's look at the argument you've presented, leaving aside exegetical questions about Hume.

1. You don't get knowledge of the empirical unobserved by reason or by observation. For example, I cannot tell that the sun will rise tomorrow by thinking about it, and by looking at it. — Humelover

First premise. Is it true that you cannot tell by looking at the sun rising right now or by reasoning about it rising right now that it will rise tomorrow?

What does the question mean? Do we mean looking at it and knowing nothing about it? Just gazing as a newborn might or a visitor from another dimension unfamiliar with our universe and how it works? What are we allowed to assume and not assume?

It's hard to say. At the very least we want to rule out any of the sorts of knowledge that are at issue in the rest of the argument, and we haven't looked at that yet. We'll err on the side of caution and not rely on anything else until we know it's okay.

Bringing no previous knowledge with us, can we tell what will happen tomorrow? No, not just by looking and not by thinking about what we're seeing. That seems obvious.

2. Causal inference will be the only way which will give you this knowledge. — Humelover

Maybe. What else could there be? We could just hypothesize that there is a regularity, a predictability to what happens without thinking of one event causing another. The sun just does this everyday, full stop.

3. To gain knowledge with the use of causal inference, we have to know causal relations. — Humelover

Causal thinking is convenient though, so we'll go with it. Then presumably what we want to predict future events is knowledge of lawlike relations: whenever A happens, B happens. Then we could use that knowledge, together with the knowledge that A has happened to predict that B will happen. We might even claim that we know that B will happen.

4. Causal relations could not be known by observation and reason. — Humelover

Now we're back to something like the first premise. How can we come to learn a lawlike fact of the sort "B happens whenever A happens"? By looking at things? Seems unlikely. By thinking about them, reasoning about them? That's more promising, if you collect in your memory all the instances of A happening and check to see if B followed. But what does that really tell you? Only that the instances you know of fit the pattern. For all you know, the very next time you're aware of A happening, it won't be followed by B. This looks like a dead end, so far as knowledge goes.

5. You can't get knowledge of things that are empirical unobserved — Humelover

What would we do to gain knowledge that the sun will rise tomorrow? We would want to know a law something like "Everyday the sun rises" and then when tomorrow comes around we could say, "Here's another day, I know the sun is going to rise". But how can we come to know this law? By watching the sun rise right now? No. By thinking about it rising now? No. By recalling that it has risen everyday up to today? No. By thinking about that? No. There's nothing left. We can't come to know such a law, so we have no rule that will allow us to infer that when tomorrow comes around the sun will rise. We can predict that, assign it a probability, but we have no justification for claiming to know it.

Does the argument make sense now? Does it seem to you both valid and sound?

I think it's okay. We've picked out the importance of lawlike statements, their use in inference, and nodded at their potential justification via induction. It's not bad.

If you were to argue against the argument you presented, what would you say? Do you disagree with a premise? An inference?

I faced some initial problems understanding your take on Hume's argument but finally managed to make some sense of it...

First off, your argument, to me, proves that even the senses are unable to guarantee knowledge of any kind because, as you said, and I quote,

You don't get knowledge of the empirical unobserved by reason or by observation — Humelover

At this juncture, it's helpful to make the distinction between tentative knowledge and certain knowledge. The former being probabilistic, uncertain, liable to change, based on new observation and the latter being absolute, certain, not subject to modification. Hume's skepticism is about how certain knowledge is impossible but we can, in that case, run with tentative knowledge.

Hume's skepticism is about how certain knowledge is impossible but we can, in that case, run with tentative knowledge. — TheMadFool

This was my understanding too. Essentially Hume is stating that it is impossible to know what the future will bring. So any knowledge that asserts with certainty of anything beyond the present cannot be true. The only way we could know with certainty, is if we saw the result in the future. Of course, we can't function at all if we don't have some belief that things are repeatable, or that certain rules and laws will remain as such in the future. The lesson is we should always be aware that knowledge is a tentative grasp, and that we can never escape needing some induction about the future in our lives.

What do you think? Is his sceptical argument valid? And is it sound? — Humelover

The way you explain it seems pretty confusing. The best thing is to go to Hume himself in his "Abstract", where he talks about himself in the third person. Hume states that there are three sources of knowledge: experience ("impressions"), relationships between concepts ("ideas") and
habits (cause, substance, principle of uniformity from the past, necessity…)

“The first proposition he [Hume] advances is that all our ideas,
or weak perceptions, are derivedfrom our impressions, or strong perceptions, and that we
can never think of anythingwhich we have not seen without us, or felt in our own minds.
This proposition seems tobe equivalent to that which Mr. Locke has taken such pains to
establish, viz. that no ideasare innate”. (Cursive by Hume)

“By all that has been said the reader will easily perceive that the philosophy contained in
this book is very sceptical, and tends to give us a notion of the imperfections and narrow
limits of human understanding. Almost all reasoning is there reduced to experience; and
the belief, which attends experience, is explained to be nothing but a peculiar sentiment,
or lively conception produced by habit. Nor is this all; when we believe anything of exter
nal existence, or suppose an object to exist a moment after it is no longer perceived, this
belief is nothing but a sentiment of the same kind. Our author insists upon several other
sceptical topics; and upon the whole concludes that we assent to our faculties, and employ
our reason, only because we cannot help it. Philosophy would render us entirely Pyrrho-
nian, were not nature too strong for it”. — Hume's Abstract, #6 y #27

If all knowledge comes from impressions, what are the relationships between ideas and habits?
The former only give coherence to our thinking. They indicate that something is greater or lesser that other or that you cannot affirm one thing and its opposite without contradicting yourself. They are merely formal.
The latter are not knowledge, strictly speaking, but mere habits, psychological habits, which come essentially from seeing the same impression constantly repeated. But they say nothing about reality.

Of course, all our knowledge of nature is based on these habits. We (almost) cannot think of a single natural law without the concept of cause, which is the one to which Hume devotes most time. But Hume seems to reduce them to nothing, pure belief.

Hume himself admits that his theory would be as sceptical as Pyrrho of Elis, the model of all scepticism, if it were not for the fact that nature comes to the rescue of knowledge. How?

Because when you have a rational and universally shared belief it would be absurd to do without it. This is a very simple principle, but it seems to be quite solid. At heart, all science is based on it. And it is the only way to bring down the solid edifice of pyrrhonean scepticism. In my opinion.

What do you think? Is his sceptical argument valid? And is it sound? — [b][/b]Humelover

Yes of course it is valid and sound. You cannot get an ought from an is, and you cannot get a will be from a was. But don't expect people to stop talking about what ought to be and what will be any time soon, because we simply do expect things to go on much as before, because that's all we got. It's not reason, but the necessity of knowledge poverty aka ignorance.

We (scientists) expect by extrapolation from the observation of the 'main sequence of stars' and other considerations, that one day the sun will not rise, but expand to envelope our planet. But there is no reason why it cannot happen that in 2 minutes the Great Cookie Monster gobbles up the universe and there is no future at all.

This was my understanding too. Essentially Hume is stating that it is impossible to know what the future will bring. So any knowledge that asserts with certainty of anything beyond the present cannot be true. The only way we could know with certainty, is if we saw the result in the future. Of course, we can't function at all if we don't have some belief that things are repeatable, or that certain rules and laws will remain as such in the future. The lesson is we should always be aware that knowledge is a tentative grasp, and that we can never escape needing some induction about the future in our lives. — Philosophim

Are you, by any chance, referring to the problem of induction? If you are then here's the problem:

Suppose we've made some observations and we've noticed that something, say X, repeats. In this regard, we have two options: 1. Believe that X will repeat or 2. Believe that X will not repeat. The current attitude, if it can be referred to as such, is to go/run with 1 i.e. most people will think X will happen again. Hume, in his wisdom, informs us that we have no valid reason to think so.

Alright! I won't argue with that but look now at the other option, the only one, left for us viz. 2. Believe that X will not repeat. Do we have a reason to believe this? Are we justified, to the same degree or more, to reach the conclusion that X won't repeat?

In a sense I'm reversing the polarity of Hume's argument - it's not just that we aren't justified in believing X will occur again, we're equally in error if we think that X won't repeat. Do you see light at the end of this tunnel?

Are you, by any chance, referring to the problem of induction? — TheMadFool

Yes. And you are completely correct. While we cannot ascertain that something will repeat, we cannot also ascertain that something will NOT repeat. Its why I liked your answer of tentative vs certain knowledge. We can be certain of what we know now. We can even make logical conclusions about the future of something based on what we know now. But that knowledge is tentative, as repeatability of the same knowledge in the future is something we cannot be absolutely certain of.

Hume himself admits that his theory would be as sceptical as Pyrrho of Elis, the model of all scepticism, if it were not for the fact that nature comes to the rescue of knowledge. How?
Because when you have a rational and universally shared belief it would be absurd to do without it. This is a very simple principle, but it seems to be quite solid. At heart, all science is based on it. — David Mo

But not Hume. Hume's philosophy is an understanding and lack of appreciation for Galilean-Newtonian science. Instead, he starts with modern Aristotle and winds up with Platonic skepticism even of well-justified opinion.

Yes. And you are completely correct — Philosophim

:rofl:

knowledge is a tentative — Philosophim

Tentative as in the future may be different from the past and the present?

Right, but just as we lack reasons to believe that the future will be same, we also lack reasons to believe that it'll be different.