"There is no logical impossibility in the supposition that the whole of life is a dream, in which we ourselves create all the objects that come before us. But although this is not logically impossible, there is no reason whatever to suppose that it is true; and it is, in fact, a less simple hypothesis, viewed as a means of accounting for the facts of our own life, than the commen-sense hypothesis that there really are objects independent of us, whose action on us causes our sensations."

Russell says "belief in an independent external world" may be called "an instinctive belief."

He notes that "in the case of sight, it seems as if the sense-datum itself were instinctively believed to be the independent object, whereas argument shows that the object cannot be identical with the sense-datum."

So he allows that a particular instinctive belief may conflict with "argument." But the instinctive belief that "there are objects corresponding to our sense-data" remains undiminished. So just because one instinctive belief makes no sense, we can still rely on the ones that haven't been fractured by argument. And in fact, "We may therefore admit--though with a slight doubt derived from dreams--that the external world does really exist, and is not wholly dependent for its existence upon our continuing to perceive it." How do we admit this? Because there seems no good reason for rejecting it.

What does he mean by admit? "It is of course possible that all or any of our beliefs may be mistaken, and therefore all ought to be held with at least some slight element of doubt. But we cannot have reason to reject a belief except on the ground of some other belief. Hence, by organizing our instinctive beliefs and their consequences, by considering which among them is most possible, if necessary to modify or abandon, we can arrive, on the basis of accepting as our sole data what we instinctively believe, at an orderly systematic organization of our knowledge, in which, though the possibility of error remains, its likelihood is diminished by the interrelation of the parts and by the critical scrutiny which has preceded acquiescence."

So we have the idea of slight doubt, and diminished likelihood of error. All you have to do to enjoy diminishment of the likelihood of error is avoid contradicting yourself and bother to ask if you might be wrong before you acquiesce. Aquiesce comes from a Latin word that means to be quiet. In English, it means to passively consent.

Can we say though, that our instinctive belief about objects in space and time does not conflict with other beliefs? Can we hold this instinctive belief without contradicting ourselves? Let's see:

Aquinas draws our attention to some instinctive beliefs:

Objects move. An object moves because something causes it to move. Unless we stop the chain of causes somewhere, we end up with an infinite regression. An infinite regression of time is inconceivable. So we either have to contradict ourselves and say there is a self-moving thing, or we have to admit that our image of events contains an inconceivable element. How does Russell address this?

"There is no good reason why a regress should be rejected, provided only it leads to no contradictions. The series of rationals greater than zero up to and including one is infinite, and yet has no first member. In the case of motion, the question of a regress need not even arise. Two gravitating particles circling round each other like sun and planet will continue to do so indefinitely."

The best I can do to make sense of what Russell has said here, is to first notice how fabulous empiricism becomes for him when talking about Aristotle. I think Russell is basically finding fault with Aquinas' argument by saying that Aquinas has failed to prove that we have to answer the question at all. There's no reason that we have to either contradict ourselves or accept an inconceivable explanation for mundane experience.

This might be more satisfying if we assumed that Aquinas was making any demand that we answer a question and had, in fact, answered one. Since Aquinas started by saying objects can't be self-moving, it follows that he understood that a prime mover doesn't make sense.

(all quotes are from The Problems of Philosophy except the one about Aquinas: Wisdom of the West)

Objects move. An object moves because something causes it to move.

Not, according to Newton's first law of motion:

Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

According to Newton, the natural state of a body is to be in motion and it will remain in motion unless stopped. This is called the law of inertia. So, it looks as if either Aquinas or Newton is wrong. I am inclined to bet on Newton.

The fact that there is no logical impossibility in supposing something is true is no reason at all for supposing it is true. It is only a reason for not supposing that it is necessarily false. Not very much, when you come to think about it.

Russell does reach that conclusion: that we do well to be modest in our expectations of philosophy.

I don't see the conflict between Aquinas and Newton. I think the law of inertia starts with "a body at rest will remain at rest unless acted upon by an unbalanced force..." then we get to how once they're moving they stay moving. But that brings up a question: which of Aristotle's four kinds of cause is inertia? Material, formal, efficient, or final?

Aquinas holds that there must be a First Mover, otherwise, motion is inexplicable by virtue of an infinite regress. Newton holds that it is not motion that requires explanation, but rest, since there is motion until some external force stops it. Aquinas assumes that the continuity of motion requires explanation, and if there is no continuing force to cause motion, the motion would stop of itself. Newton holds that just the opposite is true. That what is in motion will continue in motion until it is stopped by some external force. The views are completely opposite.

Oh I see.

The idea of inertia suggests that objects resist change in their status (whether moving or not.) So Newton has said there's no need to find an external cause for continuity of motion. The object with mass has a built-in impediment to change.

So what about this passage:

" In the world of sense we find there is an order of efficient causes. There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible." By this he means that any thing, circumstance or event cannot change itself, but can only change something else (concept of efficient cause). Since there is a string of causes in which the string cannot be infinite (see premise #1), then all causes must attribute themselves to a first cause: God."
Philosophical Proofs on the Existence of God

What is the efficient cause of an event? Isn't it a preceding event?

I don't really see how what you say Russell says has to do with my comment.

Aquinas holds that there must be a First Mover, otherwise, motion is inexplicable by virtue of an infinite regress. Newton holds that it is not motion that requires explanation, but rest, since there is motion until some external force stops it. Aquinas assumes that the continuity of motion requires explanation, and if there is no continuing force to cause motion, the motion would stop of itself. Newton holds that just the opposite is true. That what is in motion will continue in motion until it is stopped by some external force. The views are completely opposite.

Aquinas does not seem to know much physics, which is not surprising since the science of physics had not started.

If we exclude total emptiness from the equation why would something have to be caused ? ...in fact, the only way of something being ultimately "real" implies the necessity of not being caused...as cause implies change, and change implies dependence of nature...

---------- Post added 03-22-2010 at 03:05 PM ----------

...Cause is not cause... (not as we think of it anyway)...what cause is, is proof of Being !...

Newton doesn't seem to accept the old theistic argument that God is some kind of sustainer that keeps things going.

I don't know. I think that the theory you are talking about concerns the existence of the world. Not motion.

Russell says "belief in an independent external world" may be called "an instinctive belief."

True, but the science of physics didn't "start" with a complete departure from previous human thought about time and space.

So if something is dependent of nature, it's not ultimately real? For something to be ultimately real, it has to be able to exist even if you took everything else away. There isn't anything in the universe that would pass that test. Only everything itself would qualify. Is that what you mean?

So we experience change. Our images of it aren't logically self-contained. But somehow we know things about Nature. And space and time are metaphors for what we know. The mistake comes from trying to stretch the metaphor to meet the experience. Blue is a metaphor for an experience. Color and wavelength are also metaphors. You can't build a staircase from the metaphor to the experience. If you could, you could cure blindness with words. Yes? Sort of?

reveal

Sure, but it seems closely related to motion or anything else continuous.

there is no " belief " in the first place , thats the thing

the " independent external world " is necessary for any thought in the first place

for example , how does one become if not for air to breath

without air how does any living thing , evolve to thought ?

---------- Post added 03-23-2010 at 09:49 AM ----------

...Is Local, Universal ?

Local -- Universal... the difference is: one has a perspective, the other has none. There is no all-encompassing point of view.... or rather it's view is of oblivion: the opposites cancel each other out (I'm aware that sounds silly... maybe it is?)

I agree in a classical perspective of course...now, the question is if Local is not indeed Universal and whole encompassing in some odd way ? (given my above example)

---------- Post added 03-23-2010 at 10:15 AM ----------