# Non-deductive VERSUS Inductive

Emil

Thu 15 Apr, 2010 10:22 am
@fast,
fast;152295 wrote:
Yes, that's what I meant.

I think the confusion I'm having is the same confusion I had with Zetherin about whether propositions must be true or false. Just because a proposition is true/false, that doesn't mean the proposition is a necessary truth/falsity, yet despite that, not only is it true that propositions are true or false, but (and apparently because of the law of bivalence), they must be either true or false.

I posted it earlier but here it is again:

[INDENT]1. (∀P)(TP∨FP)
Necessarily, for all propositions, that proposition is true or false.

2. (∀P)(□TP∨□FP)
For all propositions, that proposition is necessarily true or necessarily false.

[/INDENT]Don't confuse them, if you do. They are not logically equivalent. I'm not sure if one of them imply the other, but I don't think so. Normal english is not very good at distinguishing between them, especially not when people add all other sorts of vague or ambiguous phrases/words such as "set in stone", "has to be", "MUST be", "must be", ""must" be", and what have we not.

kennethamy

Thu 15 Apr, 2010 10:35 am
@Emil,
Emil;152263 wrote:
You quoted me as writing something that I did not write. You must have accidentally edited it.

I don't know how that argument is supposed to show that "valid inductive argument" is a category mistake. The proposition isn't even in the argument. You will need to be more clear and thorough for me to understand you.

It doesn't follow from what you wrote that when we (that is I?) call inductive arguments invalid (non-valid, whatever), then we are accusing them of committing a fallacy. You only wrote that "when we say of a deductive argument that it is invalid, we are saying that it commits a fallacy". This has no bearing on inductive arguments. What makes a good inductive argument is not the same as what makes a good deductive argument. Validity is obviously a property of a good deductive argument, but it is not a property of a good inductive argument.

Is validity a property of any inductive argument at all? If it isn't a property of a good inductive argument, then I would not think it was a property of a bad inductive argument either. Is it a property of a "neutral" inductive argument? Are there any such? I don't think so. Therefore, if validity cannot be a property of either a good or a bad inductive argument, then it cannot be a property of any inductive argument. But, if it cannot be a property of any inductive argument then to apply the property of validity is a category mistake. QED. Unless you think, of course, that all inductive arguments are bad inductive arguments, and none of them are good. Do you think that? Perhaps you want to say that all inductive arguments are bad deductive arguments? That would be like saying that all good monopoly games are bad chess games. I suppose that makes some sense.

fast

Thu 15 Apr, 2010 10:57 am
@fast,
An inductive argument (all of which are not valid) is always not valid for a different reason than why any deductive argument is not valid.

Again, if you give me a deductive argument (that so happens to be invalid (thus not valid)), and if you give me an inductive argument (that is not valid (obviously)), then the reason why the deductive argument is not valid will always be different than why the inductive argument is not valid.

Never can a conclusion of an inductive argument be validated (or guaranteed) based on the structure of the argument-even if all premises are true. A deductive argument can have a guaranteed conclusion if the premises are true and the form is valid.

So, the critical reason as to why inductive arguments can't be invalid is the same reason they can't be valid. They lack the necessary form to guarantee a conclusion.