“Consider the following two statements

1. All criminals have broken the law
2. Reggie Kay is a criminal

You may be equally certain that both statements are true, but, according to Hume, they are true for completely different reasons. Understand what the difference is, and you have understood a fundemental distinction between two types of human knowledge.

THE FIRST TYPE:
In the first case, the statement ‘all criminals have broken the law’ is true by definition, since to be a “criminal” means to be someone who has broken the law. One way of pressing this is to say that the second part of the sentence (the predicate) merely repeats or contains what is ALREADY implicit in the first (subject). ….

One feature of tautologies is that they MUST be true. To deny their truth is to assert a logical contradiction. That statement ‘not all criminals have broken the law’ is self-contradictory and therefore necessarily false. – because it asserts that people can be criminals, and thus lawbreakers, without having broken the law. However, this cast-iron seal of truth comes at a cost. THE PRICE PAID FOR THE CERTAINTY OF SUCH STATEMENTS (according to Hume) IS THAT THEY FAIL TO DESCRIBE THE WORLD. Sentence (1) does not describe the world because it does not tell us anything about whether or not the criminals exist, which people are criminals, which laws they have broken, etc.

The sentence merely tells us something about what certain words mean. To know that all criminals have broken the law is to know something about the meaning of the words but nothing about the way the world is. (truths about mathematics and geometry fit into this, as Hume stated and Joe elaborated on. Thus 1+1=2 “must” be true hence it is seen as a tautology.)

THE SECOND TYPE
” ‘Reggie Kay is a criminal’ belongs in this category because its truth or falsehood cannot be ascertained simply by attending to the meaning of the words in the sentence. (We must look at the world to see if this is true. If he broke the law, then he is a criminal) It is what goes on in the world that makes such statements true or false, not just what the word means

(so you see, we are looking at the the what “must” be true because it is a tautology – all criminals are lawbreakers, a triangle has three sides – and what is made true or false by the world (reggie kay is a criminal, the sky is red, the meat is hot) reggie kay be definition is not a criminal, but may be somethng else, the sky by definition is not red, but something else – whereas a triangle by DEFINITION has three sides.)

“… Unlike Type (1) sentences, it is logically possible to logically conceive of the opposite statements of Type (2). Thus we can say Reggie Kay is not a criminal, but we can not say a triangle does not have 3 sides. ”

A brilliant quote I should’ve had in the article from them is “This is why so much ancient mathmatics is fundementally sound (there is no way it could be wrong) and so much ancient science utterly false (the possibility of error is always inherent in statements that describe the world)”

I hope that helps. And thank you for reading. I hope this didn’t throw you off.

And ‘Hogwash’ is not a rational argument.

The Teaching Company lecture series on the “Philosophy of Science” has a really good analysis of what science is and is not. You can buy it online… or test drive it, if one is so inclined, at thepiratebay.
Highly recommended either way. TTC rocks.

http://www.teach12.com/ttcx/CourseDescLong2.aspx?cid=4100

Ideas are different from facts. Facts are about the world. They are about things that exist.
“The apple is red.”
This is true, IF the apple is in fact red.
And its not true, it is a contradiction, if the apple is green.

There is no implict contradiction in just saying: “The apple is red.”
It only becomes a contradiction, if you have an apple that is green.

Your article has intrigued me, but I have no training at all in philosophy, and I simply do not understand what is meant by

The contrary of every matter of fact is still possible; because it can never imply a contradiction, and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality. That the sun will not rise tomorrow is no less intelligible a proposition, and implies no more contradiction than the affirmation, that it will rise. We should in vain, therefore, attempt to demonstrate its falsehood. Were it demonstratively false, it would imply a contradiction, and could never be distinctly conceived by the mind.

Would it be possible to explain it?

Thanks
Mags