Intro to Symbolic Logic - Part Two - True or False

Most statements are either true or false, but there are some that don't seem to be either, and some that seem false, but can't be proven true.

This video explains what the word "falsifiable" means, and why statements that aren't falsifiable can't be logically judged to be true.

Music "The Truth" by Handsome Boy Modeling School, with J-live and Roisin Murphy, which can be bought on iTunes or in a CD store.

Category:

Education

Tags:

• logic
• falsifiable
• philosophy
• true
• false

[andrewbrobbins]

The basis for logic is the law of non contradiction, which states that two opposing statements (I went to the party and I didnt go to the party), cant both be true at the same time. therefore any such statements are not outside logic, but are FALSE by the ordinary rules of logic. (and if you do not hold to the law of non contradiction you cannot disagree with me, since disagreement requires the law of non contradiction)

[andrewbrobbins]

Actually the statement that the sun will rise tomorrow is not true in a technical sense. It is referring to an event that has not yet occurred. Since it is logically possible that the sun could fail to rise tomorrow, it is logically possible that the statement could be false. It is only PROBABLY true, not certainly.

[bellojw]

to deep for me

[naannyms]

@Svelter Please read the entire three-part comment before replying again; thank you.

[Svelter]

@naannyms Actually, I have to disagree with the notion that human logic is flawed. Bring me a circle with a circumference smaller than its radius - or an instance where 1 + 1 = 3. Until then, I think it is you whose logic is flawed...

On the inductive logic front, surely it's better to predict things in terms of circumstances (i.e. if ALL circumstances remain the same as they were today, the Sun will rise tomorrow.)

PS If by 'human logic' you mean 'common sense', I fully agree. That is flawed

[naannyms]

@naannyms Let us take a basic premiss assumed by traditional deductive logic -that p and notp cannot both be true - and attack it on the basis of the existence of modal logics.

I could say that because modal logics are valuable tools in discovery, and because they allow for both p and notp being true, that the rule declaring an embargo on the truth of both p and notp is therefore the result of a bad assumption about the world.

Of course there are refutations, otherwise I'd not teach the rule.

[naannyms]

@Svelter When I say formal logic is "flawed", what I mean is that systems of formal logic are not all-encompassing - there are many formal logics. Modal logics may not even be strictly speaking "formal", depending on what you think constitutes a "formal logic".

Before Hume, inductive logic was considered a breed of formal logic; now, everybody is a bit less certain.

Anyone can attack any logic on the basis of its suppositions, if they know how.

[naannyms]

@Svelter Formal logic is a system invented by Man and as such is flawed. You'll find that even complex mathematical proofs must be reviewed by committee before they are accepted as proofs rather than theorems.

Furthermore, inductive logic has no set system of rules, and as such is not formal logic. For example: after how many successful dawns should I conclude that the sun is more likely than not to come up tomorrow? Any set of rules I make, you could justifiably disagree.

[Svelter]

@naannyms So you're saying aspects of logic are open to debate? That's fascinating. I always assumed that logic could not be disagreed with.

[naannyms]

@Svelter

You're raising a question about what is commonly known as the assumption of the uniformity of nature, first mentioned by David Hume.

I'll get to it at some point, but for now, let's just say that I'm not going to cover inductive logic in detail, only deductive logic, simply because the problem is not agreed upon widely enough for me to teach with any authority.

When I do cover it, it will be from the point of view of a discussion.