Nice post Pythagorean. May I ask why Leibniz wrote the letter and what your intent is with posting the letter?

I agree, nevertheless, that in the present state the external senses are necessary to us for thinking, and that, if we had none, we could not think. But that which is necessary for something does not for all that constitute its essence. Air is necessary for life, but our life is something else than air. The senses furnish us the matter for reasoning, and we never have thoughts so abstract that something from the senses is not mingled therewith; but reasoning requires something else in addition to what is perceivable by the senses...

Wow, I really like this final paragraph. I had come to the same conclusion as the first sentence on my own when I first thought about A Priori, etc. But I had never finished it up with the rest of his thinking, which I believe completes the picture to some extent. Once again in a classic debate of X vs. Y, the truth is neither and both...

In this letter from G. W. Leibniz (1646-1717) he talks about how reason is within us a priori. This seems a fine exposition of philosophical rationalism.


...BEING ITSELF AND TRUTH ARE NOT known wholly through the senses;

for it would not be impossible for a creature to have long and orderly dreams, resembling our life, of a sort that everything which it thought it perceived through the senses would be but mere appearances. There must therefore be something beyond the senses, which distinguishes the true from the apparent. But the truth of the demonstrative sciences is exempt from these doubts, and must even serve for judging of the truth of sensible things. For as able philosophers, ancient and modern, have already well remarked: -if all that I should think that I see should be but a dream, it would always be true that I who think while dreaming, would be something, and would actually think in many ways, for which there must always be some reason.

Thus what the ancient Platonists have observed is very true, and is very worthy of being considered, that the existence of intelligible things and particularly of the Ego which thinks and which is called spirit or soul, is incomparably more sure than the existence of sensible things;

and that thus it would not be impossible, speaking with metaphysical rigor, that there should be at botton only these intelligible substances, and that sensible things should be but appearances. While on the other hand our lack of attention makes us take sensible things for the only true things.

It is well also to observe that if I should discover any demonstrative truth, mathematical or other, while dreaming (as might in fact be), it would be just as certain as if I had been awake. This shows us how intelligible truth is independent of the truth or of the existence outside of us of sensible and material things.

This conception of being and of truth is found therefore in the Ego and in the understanding, rather than in the external senses and in the perception of external objects.

There we find also what it is to affirm, to deny, to doubt, to will, to act. But above all we find there the force of the consequences of reasoning, which are a part of what is called the natural light.[A letter by Leibniz to Queen Sophie Charlotte of Prusia in 1702]

As far as the motives for Leibniz's writing the letter to Queen Sophie Charlotte, it's a good question but I just don't have that information on hand at the moment, sorry to say.

In light of Leibniz's claims, I would like to know if anybody here thinks it is indeed possible that we are at all being deceived in our ordinary life in what we normally take to be reality? I mean, is everything that we 'experience' day to day just what it appears to be upon the surface? Isn't there at times a demand of effort made upon us to try and figure out what is really taking place at a certain time? Don't we have to inquire after a higher or more fundamental set of rules in order to seperate things true from things that are not apparent?

I mean, what is the use of philosophy if we believe that there's nothing under the surface that could furnish us with a brighter conception of their nature? And what is the purpose of science besides its practical benefits of improving health etc? Aren't we looking for the truth here?

If we are looking for truth, then the question arises as to how do we go about in the search; -?

Are we dreaming? It seems an important and perfectly reasonable question for someone to ask. And it seems to me that the way in which we attempt to answer this question is what makes us more or less 'empiricists' or more or less 'rationalist' philosophers.

The foundations of the Universe seem to be rational and they correspond to the reasonable, thinking person's mind. That is, I say, we are at one with the universe when we use our reason to formulate the laws of nature.

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[CENTER]"The human intellect understands some propositions, namely those of the mathematical sciences, quite perfectly, and in these it has as much absolute certainty as Nature herself. Of course the Divine intellect knows infinitely more propositions than we do, since it knows all. Yet in respect of those few which the human intellect does understand, I believe its knowledge equals the Divine in objective certainty--for here it succeeds in understanding necessity, than which there can be no greater certainty (Galileo Galilei, Dialogo sopra i due massimi sistemi del mondo, Ptolemaico e Copernicano, 1632). [/CENTER]

I would deny this because it is through the senses that we grasp reality, and reality which teaches us reason.

Everything is for the most part what it seems to be on the surface. We can remove layers of reality from every single thing only to find another under. I am not saying it is not entertaining. It is the one fact of life that actually makes me believe there is a God. Yet, the essential question is not essence, but meaning. We can see what it is, and looking harder and deeper does not reveal more per unit of effort; but, to find meaning requires a relation of self to the being. Who does it mean to?



The same question one may ask of reality can be asked of philosophy or science; and that is: What is the use? Use is a form of meaning, just as is truth. You will hardly discover something untrue in finding a use. But use is a form of meaning that contributes to reaching the goal of all human activity: The Good.

How, would you say, do we know that all dogs are animals, or that all bachelors are unmarried males? Or, that things equal to a third thing, are equal to each other? Or, even, that if I know that X is y, then I know that X is y is true? What did I sense, to know any of these?

Fido, I may agree with you that the goal of all human activity is 'The Good'. But I disagree that it is to be found on the surface or at least can so easily be found or aquired or grounded in principle in our thoughts and consequently in our behaviour.

Also science reveals a world that is quite unlike the world as we experience it in daily life. When we look at or perceive a woman's breasts for example, we (or at least I) don't view clusters of skin molecules or atoms of carbon. When science looks in microscopically or looks out macroscopically what it does see and what it theorizes about seems far removed from what our daily realities are like.

And what about the detectives? Why would we need police detectives or Sherlock Holmes if everything were just as it seems upon the surface of things? Why do we need medical doctors with their scientific equipment etc.. So there must be a reality that the hard sciences hint of and that is only partially revealed to us in our crude daily lives.

I think we need the rationalist's philosophical method which we can use to peel back all of the layers of reality to let us bask in the ultimate power of existence, the fundamental purity of nature (which maybe something like God), and this method may be provided to us through the systems of Descartes, Spinoza or Leibniz, who are as rationalists claiming such a method. But the harder and deeper effort that is required must be tied to their method which appears to be essentially mathematical.

The point is that we are not at a high enough reality in our historical scientific development. Such a time will come when we live in virtual reality environments, when our environments become mathematized and thoroughly computerized and we will begin to see things as they really are, I beilieve. Until then we have to dream and visualize and press forward and try to get to a position where such truth lies.

Of the first, it is not only whether dogs are animals, but whether all dogs are dogs, which is to say not cats, or some other beast. We need to use all our senses to determine what things are as compared to what they appear to be, or are not, but appearance is first. If through no other method we learn identity through experience, which begins to build a catalogue through syllogism. Ultimately, to have some certainty we must destroy some dogs to compare them, first making certain they can be killed as all animals, and then finding in what ways they differ from other animals. Here is the rub: No matter how many dogs we show are animals we cannot ever be certain that all are. We always have to accept a standard of truth short of certainty, so it is not true at all. As Leibniz said: Iron does not float. But, iron boats float.

Of the second, this is cultural knowledge only true for a certain culture, but culture demands all the senses, and a cultural memory.

Third, As Leibniz points out; this can easily be shown with a balance scale, and to test the scale for true one must exchange weights on the scale. With this we are showing that gravity acts upon equal masses with equal effect. Clearly logic can push knowledge further into the realm of ignorence. Can we say, as in the example of the asymptotes that all things follow logically determined laws indefinetly? Without the ability to show what is true at any point we have no means to say what is true at every point beyond our grasp, so knowledge is gained by a very laborious process of pushing back the carpet of ignorence an inch at a time. Insight and creativity find a jimmy bar out of necessity. And it still has to be proved to be true.

Now, science is determined by senses, and senses are behind every scientific instrament. There is no science for justice, or virtue because these are not tangible qualities. Yet, with every scientific investigation we test what in general terms we can sense. What is the weight of a thing, what is its density, what is its shape, what is its temperature, what sound does it make, is it smooth or soft, does it have a charge, does it have a scent, does it decay, what is its color, what is its taste? Science is based upon tangible qualities that as we learn more of we can amplify, and measure more finely, and this is the basis of understanding and technology. We have evolved to our reality, and what is real is also logical. We do not invent logic, but discover it.

We need our senses to know that all dogs are dogs? (The sentence "all dogs are dogs" is not equivalent to the sentence, "all dogs are not cats" nor does it imply that sentence). All we have to know, to know that all dogs are dogs, is the general truth that All A is A, Of the law of identity. Which is a logical truth. For All dogs are dogs is a substitution instance of, all A is A. And all A is A is just a logical truth which we know a priori , which is to say, independently of our senses. There are no observations which can either confirm, All A is A, nor disconfirm, All A is A. And thus, no observations that can confirm All dog are dogs, or disconfirm, all dogs are dogs. If you can think of one, please let me know about it.

Don't you believe that to tell what a thing is you must be able to tell what it is not, what it is like, and what it appears like and what it is unlike? Dogs do have a lot of near relations and a great range of size. They may be all canines, but there the nearest part of their relationship ends, and even while each may appear like the other, appearances lie. Deeper study is always warrented.

Sir I wish not to offend thee in front of thy friends but thou art terribly full of it on the notion of identity. Identity is never proven, so it is not logical truth, but it is the axium upon which all logic depends. May I suggest that there is a great deal of difference between one standing on a bridge, and having a bridge standing on one. So, now we have Identity, in this case, as a predicate, that a dog is a dog. So how do we begin seeing if our dog is actually a dog when compared to the conceptual, and identical dog without reference to our senses? Let me ask you: If you saw a Jackel running around the streets of San Juan, would you know if it were a dog or not? How about a Fox? That tail is hard to miss. What do you know?

So, I would say there is nothing lawful about identity, and guess rather that it is a principal. And, I believe this is the point of syllogism, which is not strictly logical because it is not infallible, and that is, to establish an identity. And while I am disabusing you let me say something else. Mathamatical A, which is to say both logical and unreal identity together is not the same as a real identity. Dogs are inestimably more complex than A's. All A's are hypothetical. All conceptual dogs, as an identity are also hypothetical, but real dogs are anything but hypothetical. We live in the real world, and not in the perfect world of perfect concepts. But I would rather be a real dog in Puerto Rico than a conceptual dog in the best dog dictionary.

Of course you can prove that A is A. You can set up a truth table and show that it is a tautology. And therefore, it is a logical truth. ) All logical truths are tautologies, and all tautologies are logical truths. You do know what a truth table is. Don't you? The law of identity is one of three laws of logic. The others are: the law of the excluded middle; A or not-A; and, the law of non-contradiction, not both A and not-A. All the laws of logic are logical truths, and can be proved to be logical truths on a truth table. This is elementary logic.

You can google it easily enough, so you needn't take my word for it.

That, indeed, is a shame.

Replying to Pythagorean, NeitherExtreme, kennethamy and Fido:
When speaking of how information presents itself to us we cannot ignore the senses, nor the cognitive faculties. Both have a prt to play. David Hume, in his work "An Enquiry into Human Understanding", supports the opinion that if ever we have an a priori judgement on anything, it is made on the basis of a posteriori judgements of prior experiences or perceptions. He bases his thoughts on the fact that if we mean to structure things, we need prior information to compare our perceptions to.

Oh sure. That's why Kant in his Introduction writes that although all knowledge begins with experience, it does not all arise out of experience. We need experience in order to acquire our concepts. But that does not mean that we must have experience in order to know how those concepts are correctly connected. That every event must have a cause is supposed to be known a priori. Now, it is a necessary condition that we have experience to learn the concepts of event and of cause. The acquisition of concepts comes out of experience. But, one we have those concepts, how do we know (if we do) that every event must have a cause? It is that we know a priori. Kant makes the important point that synthetic a priori judgments are necessary judgments. What we know is that not only do all events have causes, but all events MUST have causes. Experience, Kant tells us, may teach us that all events do have causes. But how, Kant asks, could experience teach us that all events MUST have causes? There are no logical necessities in experience. Experience can teach us only about what is true, but not what must be true. The same is true of less controversial cases. Take, "All dogs must be dogs" (it is not just that all dogs are dogs). How did we get the "must" from observation? Perhaps we observe that all dogs are dogs, but how can we observe that all dogs must be dogs?

In light of Leibniz's claims, I would like to know if anybody here thinks it is indeed possible that we are at all being deceived in our ordinary life in what we normally take to be reality? I mean, is everything that we 'experience' day to day just what it appears to be upon the surface? Isn't there at times a demand of effort made upon us to try and figure out what is really taking place at a certain time? Don't we have to inquire after a higher or more fundamental set of rules in order to seperate things true from things that are not apparent?

I mean, what is the use of philosophy if we believe that there's nothing under the surface that could furnish us with a brighter conception of their nature? And what is the purpose of science besides its practical benefits of improving health etc? Aren't we looking for the truth here?

If we are looking for truth, then the question arises as to how do we go about in the search; -?

Are we dreaming? It seems an important and perfectly reasonable question for someone to ask. And it seems to me that the way in which we attempt to answer this question is what makes us more or less 'empiricists' or more or less 'rationalist' philosophers.

The foundations of the Universe seem to be rational and they correspond to the reasonable, thinking person's mind. That is, I say, we are at one with the universe when we use our reason to formulate the laws of nature.

----------

[CENTER]"The human intellect understands some propositions, namely those of the mathematical sciences, quite perfectly, and in these it has as much absolute certainty as Nature herself. Of course the Divine intellect knows infinitely more propositions than we do, since it knows all. Yet in respect of those few which the human intellect does understand, I believe its knowledge equals the Divine in objective certainty--for here it succeeds in understanding necessity, than which there can be no greater certainty (Galileo Galilei, Dialogo sopra i due massimi sistemi del mondo, Ptolemaico e Copernicano, 1632). [/CENTER]