Jack asked:

Aristotle, Newton and Einstein proposed radically different explanations of gravity. And yet, according to Hume, they associated their sense experiences together by using the same patterns. According to both Descartes and Hume, they accepted the same fundamental principles of logic. If Hume and Descartes are correct, why did Aristotle, Newton and Einstein disagree about gravity? Is there simply no foundation one can use to determine whether or not Aristotle, Newton or Einstein was correct?

Answer by Craig Skinner

What a very good question, bringing in key issues in both general philosophy and philosophy of science.

The short answer is that the foundation one can use is the scientific method of conjecture and testing. Put simply, we formulate a hypothesis (conjecture) as to how things work, and test it against the world by observation/experiment looking for confirmation (findings support the hypothesis, we can run with it meantime) or refutation (findings rule out the hypothesis, we must amend or replace it).

To deal first with the three hypotheses.

Aristotle

Hypothesis: things move to their natural place.

His conceptual framework was Earth as centre of the world surrounded by moon, sun, planets and stars going round it. He conjectured that things moved to their natural place. A stone, composed of the element earth, fell to Earth; a flame, composed of fire, moved up to the (fiery) heavens. He had no notion of gravity. If we ask why doesn’t the moon fall to Earth, he might say that it isn’t composed of earth (the moon wasn’t known to be a rock then), or that, like the planets/sun/stars, it is constrained in its orbit by a crystalline sphere. Why don’t we see the latter? Ah, it’s invisible. You can already see that the account is made resistant to refutation by what we think of as ad hoc auxiliary hypotheses such as crystalline spheres. And it appeals to purpose (things go to natural places) rather than mechanism. So it’s not a scientific hypothesis.

Newton

Hypothesis: things move under the influence of the force of gravity.

His conceptual framework was heliocentric. He saw that the movement of apples, stones, moons, planets, sun, Earth, comets and cannonballs alike could all be explained in the same way, namely as masses moving (as described by his laws of motion) under the influence of a single force (gravity). It was a wonderful synthesis of all motion, on Earth and in the heavens, and its empirical success assured its acceptance. It predicted the exact times of future eclipses and of cometary returns, and in due course Newtonian calculations were good enough to get men to the moon and back. This success rather silenced it’s philosophical critics.

Leibniz complained that, whereas Descartes proposed things stayed in orbit by being caught up in vortices, at least a coherent notion, Newton was as bad as Aristotle, proposing a force mysteriously acting at huge distances. Put simply, how could the moon know that the Earth is there, being 250,000 miles away, and so go round it. If the Earth was snatched away, how could this affect the moon – would it still go round the void where Earth had been? Newton was acutely aware of this “spooky action at a distance” criticism, and made clear he was only describing (modelling we would say these days) reality, and as regards what the force of gravity actually WAS, “framed no hypothesis (“hypothesis non fingo”). Neither did anybody else for 200 years.

So, despite the philosophical conundrum, this account is a good (excellent) scientific hypothesis, and all observations were supportive, save for anomalies in Mercury’s motion, which were just ignored.

Einstein

Hypothesis: things move freely, acted on by no force, through curved space.

His conceptual framework was the same as Newton’s. In addition, he formulated the Principle of Equivalence: me, standing on Earth subject to downward gravity and feeling upward pressure on my soles is equivalent to me in outer space being accelerated by a force acting up through my soles. Similarly, me falling freely to Earth from a balloon is equivalent to me at rest in outer space – I feel no force. So, in his theory of gravity, a body falling to Earth is subject to no force. It falls freely BUT its trajectory depends on the curvature of space itself, and this depends on mass in that neighbourhood. – mass tells space how to curve, space tells mass how to move, as we can put it.

Einstein’s and Newton’s theories made different predictions as to Mercury’s orbit and as to stellar appearances at the time of a solar eclipse. Observations confirmed Einstein’s view. And no observation contrary to the theory has so far been made. And, a practical note, although Newtonian calculations get us to the moon safely, they are not good enough for accurate satnav location in city streets, the software is Einsteinian.

So, a better theory than Newton’s (which was already an excellent one), and no problem with action-at-a-distance (there is no force so acting), although one worries about whether space curving is philosophically squeaky clean.

But not the last word. Quantum mechanics is equally well established, and the two theories are incompatible at the ultra-micro level. So, much current effort in physics goes into looking for a quantum gravity theory (string theory and loop quantum gravity are contenders).

So, to summarize, the scientific method replaced Aristotle’s view with a better one (Newton’s), the latter has been replaced by an even better one (Einstein’s), and it is likely that a quantum gravity theory will replace that. No theory can ever be PROVEN to be correct (although probably many are).

To deal now with the cognitive part of your question – how come different people, using the same logic (Descartes, Hume), seeing the same things and associating their perceptions using the same patterns (Hume), come up with different explanations of, say, gravity.

Many everyday truths are manifest, such as now it’s autumn, I’m drinking a glass of wine as I type this, etc. But many truths about the world are hidden, not manifest, such as what makes the moon go round the Earth. So we must grope our way towards them by conjecture and testing, and new conjectures can occur by association/ connection of ideas that nobody thought of before. Let’s accept the Humean story that we associate ideas by contiguity, by similarity (resemblance), by cause-and-effect. Newton saw a similarity that nobody had thought of. He saw that the moon and an apple SIMILARLY fall to Earth. In the apple case, the trajectory hits Earth. In the moon case, although forever falling to Earth, this is counterbalanced by its inertial movement tending to carry it off into space, so that it orbits rather than hits the Earth.

Another famous new connection of ideas by similarity was Darwin’s. Everybody knew that plants/animals could be changed by selective breeding (artificial selection), Darwin saw that nature SIMILARLY worked by selective breeding (natural selection). Finally, Einstein’s realization that falling freely to Earth is SIMILAR to being at rest in outer space (Principle of Equivalence) helped him formulate his theory of gravity. In short new links can be made between different conceptual maps, and cognitive neuroscience has gone some way to clarifying the physical (neuronal) basis of this.

Craig Skinner at PhiloSophos.com

 

Answer by Helier Robinson

Aristotle, Newton, and Einstein were doing philosophy of nature, which later came to be called empirical science. And empirical science is an excellent foundation one can use to determine which was correct. Aristotle was weak on physics (but strong on biology); he thought gravity was simply the desire of things to reach their own place. Newton had the advantage of knowing Galileo’s principle that thins always move in a straight line unless acted upon by an outside force (he made it his first law) and of knowing Kepler’s laws of planetary motion. Also, Galileo had pointed out that the book of nature was written in the language of mathematics; and Newton was one of the greatest mathematicians who ever lived, while Aristotle disliked mathematics.

Notice that Newton did not have an explanation of gravity: he explained motion and forces, velocities and accelerations. His physics is very good for everyday purposes; it fails only under extreme conditions that he could not have known about in his day, such as very high velocity. Einstein improved on Newton, and also explained gravity as being due to the curvature of space-time. The main difference between all three is the amount of known science they had available to them.

Helier Robinson is Emeritus Professor in Philosophy, University of Guelph. His books are available from http://SharebooksPublishing.com.

 

Ashley asked:

First of all, thank you for this! My question is regarding the philosophy of colours. What is the use of having a philosophical account of colours if science already has an explanation to the nature of colours, or explanation as to why we experience them? Also, why is it important that in any philosophical account of colours, we must preserve the common sense view of colours (common sense reflection tells us that objects ARE coloured, objects have colour). Why is this so important? Couldn’t we just say that our common sense views can sometimes be wrong? I mean isn’t it known in the philosophical landscape that some common sense views are deceiving?

Answer by Jürgen Lawrenz

Too many presuppositions for such a short question! What makes you say that science ‘already’ has an explanation of colours and why we experience them? It has no such thing. Whatever you read (providing you understood it) must have led you up a garden path. But I think you probably misread, because any proper science text would tell you that colours do not exist. Therefore the question does not concern colours as such, but why we humans see colours when (objectively) there are none.

So now that we have cleared this up, we can start with a differentiation such as you seem to be asking for. Philosophy sought an answer to this dilemma centuries before there was any science. For instance Th. Hobbes said exactly the same thing as I just did about 400 years ago. What science achieved was basically the knowledge that our colour vision formed itself on the basis of certain radiant energy emanating from the Sun which is was important for humans to understand. Since everything we see involves the reflection of sunlight, it was a survival advantage for us to be able to see certain phenomena in a certain way, that is, in colours. Essentially therefore colours inform us about objects in the world which we would otherwise have great difficulty discerning properly. This is neither deception nor illusion: it is survival necessity. Hence it not ‘common sense’ to dismiss colour vision, but plain nonsense.

When you prick your finger with a needle you have a pain. No arguments. But the pain also does not exist, any more than colour does. It is merely another species of energy travelling up a nerve. So you need to put your dismissive tone of voice away, because as a human being, you need colour vision just as you need a pain sense. To be a human being means that you need some means of orienting yourself in the world to avoid becoming extinct; and colour vision as well as pain are pretty good techniques to help us along!

Philosophy comes in where science cannot make sense of things at all. Namely: why we feel pleasure or displeasure seeing certain colour combinations. This also has something to do with survival values, although it goes back so many generations that we’ve basically lost track of it. But if you take as an example that some berries have colours that act as a warning of poison, whereas others have inviting colours, making you want to eat them, you would be on the right track. It is suggestive to think that therefore our ancestors used ‘friendly’ colours to adorn themselves and their homes, and painted their enemies (human and animal) in ‘unfriendly’ colours. All art thrives on deep-seated instincts of this kind.

But the proof of the pudding is in the eating. I suggest you start wearing colour-eliminating glasses, so that you see everything in black and white. Black and white is plain sailing: either there is light or there is none. See how far you get without bumping into things, mistaking hundreds of things for what they really are. It’s as good a cure I can think of for all those people who harbour the illusion that colours are intrinsically deception! Good luck with your experiment!

Jürgen Lawrenz at PhiloSophos.com

 

Dennis asked:

I’m not sure if this is for you, a physicist or a priest. But here goes. Mankind is roughly 3.5 million years old but eventually (to my knowledge) the sun will die in 5 billion years. Before that all water will boil away in 1 billion years. Is that the end of human life and if so why are we here? I realize interplanetary flight is severely limited by distance and even 1 billion years is an ‘eternity’ BUT that day will come. Do you have any views? Kind regards.

Answer by Craig Skinner

Your question is one for everybody – philosophers, physicists, priests and others, alike.

You link what I think are two separate questions:

1. Is the sun’s death the end of human life?

2. Why are we here?

I will give you my views on each.

1. The end of human life

First, human life is already reduced to a single species (H. sapiens, appearing 150,000 years ago), all twenty two other Homo species having gone extinct, the last being H. neanderthalensis about 30,000 years ago. And it is unlikely that H. sapiens will split into new species here on Earth, given that we are an interbreeding global species sharing essentially the same habitat. Of course if groups of us ended up on different planets, divergent evolution could occur.

Secondly, we may go extinct long before the sun dies. It’s unclear whether our occupancy of the cognitive niche in the biosphere is stable long term. We may make such a mess of things, one way or another, as to go extinct.

Thirdly, all life on Earth will indeed die when (or before) the Earth is destroyed by changes in the sun. The only hope for our distant descendants, or for the then dominant intelligent kind, whether biological or artificial, is to find alternative accommodation. This may be easier for AI life forms who don’t need water, oxygen, food or gravity, although of course all life needs energy. One really suitable planet not too far (!) away would give us another billion years or so, and it’s quite likely that one will be found and reached in the time available. It is possible that our distant descendants, or the superintelligent AI life forms that replace us after the ‘singularity’, will have colonized the galaxy long before the sun dies.

2. Why are we here?

I take it you ask life’s meaning or purpose, rather than an account of how evolution by natural selection produced us.

My view is that we can have only the meanings and purposes we set for ourselves. And this is so whether we live for a day or a billion years.

Many think that the existence of a benevolent, omnipotent creator gives our lives meaning. But it seems to me this just moves the question up a level. For we can now ask what is the meaning or purpose of God’s life. On the Judaeo-Christian tradition, God doesn’t even enjoy a social life among equals, as humans can; indeed he doesn’t recognize other gods as equals (‘no other gods before me’ etc). The point of his life appears to be love. But this seems to me to be a good point. We humans can do likewise whether or not gods exist. The 20th Century philosopher

John Macmurray felt that Descartes set us off in the wrong direction with ‘I think therefore I am’, and that humans are essentially agents so that ‘I act therefore I am’ is a better starting point for philosophy. He goes on to say that ‘all philosophy is for the sake of action, all action for the sake of love’. If this includes love of truth, beauty and humour as well as of fellow humans, it seems a fair basis for living out the rather absurd situation we find ourselves in by existing.

Craig Skinner at PhiloSophos.com

 

Answer by Geoffrey Klempner

Even if as Craig says there is a chance that human beings could ‘colonize the galaxy’ before life on Earth is extinguished, it is considered probable that the universe itself has a sell-by date defined in terms of entropy, the so-called ‘heat death’ theory. That’s a very long way away, but adding noughts doesn’t make any essential difference to Dennis’s point. Which is that somehow, we feel that if life has any real point or value, it must go on forever.

I won’t debate this factual claim, which is a major element in religions that preach the existence of an ‘after life’. My query concerns how this could possibly solve the problem of the meaning of life. All we seem to be asking for is ‘more of the same’, without end.

That’s why more thoughtful interpretations of religious doctrine speak of the ‘eternal’ as something essentially different from the numerically infinite. My own view as an atheist is sceptical. However, supposing we were, or had the capacity to become, eternal, like God, wouldn’t that mean that we are not essentially finite beings? And, if not finite, how would one make a distinction between ourselves and the kind of being that we take God to be?

A finite being that merely ‘lives forever’ remains dependent on its creator. It continues to exist, or ceases to continue, as God decides. To exist eternally is to exist beyond any such relationship of dependency.

http://www.philosophypathways.com/vita.html

 

Phil asked:

I’m having a difficult time grasping what exactly is Kant’s ‘Transcendental Unity of Apperception,’ and the role it plays in regaining objectivity in the world since according to him, the only world we can know is one that our minds construct through sensibility, understanding, and judgements.

Answer by Geoffrey Klempner

I’m going to try to give a simple account of Kant’s notion of the Transcendental Unity of Apperception and the role it plays in his philosophy. You are right to be suspicious about the kind of ‘objectivity’ that this theory can account for.

Let’s start with the question: what is the difference between one self and two selves: me and you, for example? Well, you have your thoughts and feelings, and I have mine. You have your body and I have mine. However, it would be logically possible for me to have your body as well as my own, your thoughts and feelings as well as my own. Then we would be looking at the individual, Phil-GK who only appears to others as two separate people.

Or one could consider the possibility that I suffer from a radical form of multiple personality disorder. In which case there would be two individuals, GK1 and GK2 ‘sharing’ my body.

In either case, there are various ways in which one could empirically verify that Phil and GK had ‘fused’ to become Phil-GK, or that the individual known as ‘GK’ is in fact two people, GK1 and GK2.

Science fiction possibilities aside, the point here is that it is in some sense a given, and hence ‘a priori’, or known prior to any empirical verification, that the self is a unity. Even Hume, with his ‘bundle theory’ of the self accepts that at any given time, if ‘ideas’ x and y are in the same bundle, and ideas y and z are in the same bundle, then x and z are in the same bundle.

So what? Descartes famously drew the conclusion that the self is a thinking substance. That’s what it’s identity consists in. This is a fallacy, according to Kant. (He goes to great lengths in showing this in the section of the Critique entitled, ‘Paralogisms of Transcendental Psychology’.) Briefly, the upshot is that the substance theory explains everything and nothing. Maybe GK is two thinking substances, or a hundred thinking substances, and I would never know. Or maybe my thinking substance changes its identity every second, each substance transferring its states to the next substance when it ‘dies’ like a line of colliding pool balls.

Now comes the brilliant part. We want the idea of unity to do some work, otherwise it is just free-wheeling, ‘a knob which turns, although nothing turns with it’ as Wittgenstein says about a similar matter in Philosophical Investigations.

Kant realized that the only way to give a meaningful role for the identity of the self is as a logical constraint on the kinds of experience that are possible. A Cartesian thinking substance can have any kind of ‘experience’, because for Descartes all experience basically is is a series of perceptions spread out in time. But our experience isn’t like this. It is ‘as of’ a world of objects in space.

What if, Kant thought, we simultaneously construct a story of the self and its progress through the world, and a story of the world and the objects in it? The ‘Transcendental Unity of Apperception’ now becomes a logical constraint on what kinds of experience are possible. The dramatic conclusion, which Kant took as to be an answer to the scepticism expressed in Descartes’ First Meditation’, is that experience is only possible if it is experience ‘as of’ a world of objects in space.

The story of a world of objects in space and a self which traces a path through that world is a theory. Raw experience (or ‘intuition’) is evidence for that theory. If it isn’t, then it is not ‘experience’ in any meaningful sense. If I know that I exist, as a subject with an identity, then I know that there exists a world of objects in space (‘Refutation of Idealism’, 2nd. edition).

But what has Kant proved, really? The ‘world’ is a theory. It is my theory. Everything I will ever experience relates to the experience of being a subject in the world. But all this could be true if all that existed, in ultimate reality, was raw experience together with a mysterious power of melding it together into a ‘story of a world’. In other words, you can be a fully fledged solipsist and accept everything Kant says about the necessary existence of an external world.

http://www.philosophypathways.com/vita.html

 

Christopher asked:

We say that faith is unjustified, but don’t we have faith in reason and logic? We always base our beliefs, which we consider to be true, on our past experiences and we assume (i.e. have faith) that our future/ present experiences will be similar. We believe that if we drop a pencil it will fall because that is what has always happened, and it still takes faith to believe it will happen again. If this is true then what can we base our knowledge on?

I’m aware of Descartes proof of the existence of the self, but even this can only be true if reason itself is infallible, which I seriously doubt. A philosopher once showed that motion is an illusion using reason and logic. Paradoxes exist. We have numbers that are non-repeating and nonterminating, yet correspond to something finite and material. I’m using reason to show that reason is infallible and if the rules of reason imply that reason is unreasonable (untrue) then something seems to be wrong. Am I right?

Answer by Craig Skinner

Your question bears on the ‘epistemological turn’ in philosophy which began with Descartes, continued through Locke, Berkeley, Hume, Reid and Kant, and was reinvigorated by Gettier and Quine fifty years ago.

You are right about one thing. We can have no absolutely certain knowledge. Ultimately we base our beliefs on reason or perception. Both can be faulty, and we can’t prove that either produces true beliefs. Reason can only be justified by reason, a circular argument which Descartes is guilty of using, as you say

But this doesn’t mean it is unreasonable to rely on our considered beliefs, or that they are wrong. Most of them may well be right. It’s just that we can’t prove them, so that, as you say, we are fallible, we must live by faith (understood as reasonable assumption not as blind faith going against all evidence)

Let’s briefly consider induction, reason and perception.

First, induction. Yes, it takes faith to believe the pencil will fall next time I drop it. So what. The whole of nature relies on induction in the sense that past regularities are hardwired into genes and brains. Right now the tree in my garden is shedding its leaves, in anticipation of winter, and in a few months, will sprout new ones, in anticipation of summer. My dog is looking at me expectantly as the time for her walk draws near. And I don’t think the tree or the dog will be disappointed. Of course, As Hume says, we can’t justify the necessity postulated by causation or laws of nature, and so can’t be sure the future will be like the past. Moreover, even if we do accept a necessary connexion between constantly conjoined events, this has only been up to now, and we can’t be sure it will hold in the future. But it is still reasonable to rely on it, we all do, we can’t do otherwise, as Hume himself says.

As for reason, there has been a traditional presumption in philosophy that truths of reason (analytic, necessary, apriori), although not telling us anything about the world, are especially reliable. Whereas, truths arrived at by observation (contingent, a posteriori), although telling us about the world, are less reliable. I suggest that because neither reason nor perception can ultimately be justified, all truths are on a par. On this I side with Thomas Reid and Quine. As Reid says:

‘Why, sir, should I believe the faculty of reason more than that of perception? – they came both out of the same shop, and were made by the same artist: if he puts one piece of false ware into my hands, what should hinder him from putting another?’ (Reid T [1764]: An Enquiry into the Human Mind on the Principles of Common Sense).

Reid’s point holds whether we regard (with Descartes) the ‘artist’ as God, or (with Hume and Darwin) as nature

As for perception, as I say (with Reid, Moore and Quine), it is on a par with reason. To be sure, we can’t PROVE the external world exists. But (as GE Moore said, and illustrated by his notorious ‘hands’ argument), we don’t know about things in the external world by proof, we know about them by perception.

So, I go for a moderate, wide, foundational, naturalistic epistemology: moderate, in that I am content with fallible knowledge; wide in that I know of an external world, other minds and moral truths; foundational in that my belief system is supported by basic beliefs founded on reason and perception; naturalistic in that I think evolution has seen to it that my perception and reason are generally reliable.

Finally, I wont deal here with paradoxes of motion or issues to do with irrational numbers, except to say that I think any paradoxes arising are only apparent logic inconsistencies, not real ones when considered in depth (Achilles is not really still chasing that tortoise!). So, I don’t think ‘the rules of reason imply that reason is unreasonable (untrue)’ as you put it.

Craig Skinner at PhiloSophos.com

 

Bill asked:

I am not a philosopher or educated in philosophy, but I like to break what I observe around me down into common factors.

I have arrived at the tentative conclusion that everything is motion. It seems to me that while we are used to thinking of movement as being something that things do that the opposite is in fact true; things are something that motion does.

My question is, has any philosopher said something similar to this? I’d like that philosophers name and referred to writings on the subject.

Here are the questions that bring me to my conclusion. What exists that does not move? Does anything have an aspect or property about it that is not constituted by motion? Can any thing be distinguished from anything else except by means of motion? How is space conceivable apart from motion? How is time conceivable apart from motion?

Isn’t everything reducible to motion? And if so, wouldn’t that mean that every property or attribute which constitutes the nature of anything is nothing more then various velocities contrasted or interacting with one another?

Answer by Jürgen Lawrenz

There is such a philosopher. His name is Leibniz and his theory of the monads is fundamentally the explanation of the force which lies at the bottom of all reality. Simplifying his thought: It is nonsensical to suppose a ‘container’ (space) with nothing in it. Likewise it is impossible to speak sensibly of time without something happening. ‘A thing exists where and when it acts’. Accordingly all things (past, present and future) exist in two relationships to each other, namely their relative mutual succession and their relative mutual orientation. But this can only be discerned in terms of changing temporal and spatial arrangements, i.e. their motions. These motions are therefore the ultimate source of time and space. But the motions obviously imply some force, so it is a conception of universal (or residual) force we get from Leibniz.

The problem for you might now be that following up your idea with reading Leibniz is more difficult than with other philosophers. He did not write a book on the subject – in fact most of his philosophical writings are letters and essays, so that finding and compiling the relevant texts is a pretty taxing job. To date, no editor of Leibniz seems to have seen fit to collect them all in one publication.

So you have basically two ways to find your entry into this literature. Get yourself a fat book of his papers, e.g. Philosophical Papers and Letters, edited by Loemker; or Philosophical Writings, edited by Parkinson and find what you need. This is likely to be frustrating. The alternative is to read my comprehensive account of Leibniz’s theory. Check it out here.

Jürgen Lawrenz at PhiloSophos.com