Whatever. (Symbols...)

All arguments are valid or invalid.

Invalid = not valid.

Is this another case of your reluctance to accept the common usage of negation prefixes? (IN-, UN-, NON-, ANTI-, etc.) like with the previous "unjustified = non justified" confusion?

By "invalid" I mean "not valid" and nothing else.

Questions:
[INDENT]1. Are there valid inductive arguments? No
2. Are there non-valid inductive arguments? No
3. Are there valid deductive arguments? Yes
4. Are there non-valid deductive arguments? Yes
[/INDENT]

I am not valid. Does it therefore follow that I am invalid?:rolleyes:

To say so is your own logical fallacy, just as you conclude that because no inductive argument is valid, any inductive argument is therefore invalid.--This argument is invalid in itself, and the conclusion itself is false.



This is false. All arguments are either valid, invalid, strong, or weak--and/or: sound/unsound or cogent/uncogent.



This is false. "X is invalid" actually means "X is non-valid."



These prefixes only negate the predicate. They don't negate propositions. Confusing the two is precisely why your view is a category mistake. All category mistakes are logical fallacies.



Then you would be wrong.


For all Inductive arguments Px, for all valid arguments Qx, and for all invalid arguments non-Qx...

~(Ex) (Px and Qx)

is true.

And it is not logically equivalent to,

(Ex) (Px and non-Qx)

They are not the same thing. The first say there are no valid inductive arguments; the latter says there are some invalid inductive arguments. The first does not entail the second.

Rather, the situation looks like this:

(1) ~(Ex) (Px and [Qx or non-Qx])

which says that no inductive argument is either valid or invalid, is NOT logically equivalent to

(2) (Ax) (Px --> [Qx or non-Qx])

which says that all inductive arguments are either valid or invalid.

The former is true. The latter is false.

But (1) IS logically equivalent to,

(3) (Ax) (Px --> ~ [Qx or non-Qx])

which says that all inductive arguments are neither valid nor invalid. And (3) is true just as (1) is true.

Your view is an equivocation on negation "it is not the case that" and the predicate "invalid."

In other words, "X is not valid" does not mean the same thing as "X is invalid" or "X is non-valid."

I am not valid, but I am not thereby "invalid" or "non-valid."

Again, category mistake.

Further, "validity" just means

For all deductive arguments, if the premises are true, then the conclusion must be true.

But the definition of validity, here, does not tell you that the feature of validity applies to anything beyond the domain of deductive arguments.

"Strength" (analogous to validity) just means,

For all inductive arguments, if the premises are true, then the conclusion is probably (more likely than not) true.

But just because validity is not a feature of strong inductive arguments, it does not logically follow that invalidity is a feature of strong inductive arguments.

This, in itself, is your logical fallacy here:

No inductive argument is valid.
Therefore, all (or at least one) inductive arguments are invalid.

*This argument is invalid, and the conclusion is even false.

(a) No P are Q

does not entail,

(b) All P are non-Q

nor does it entail,

(c) Some P are non-Q

at most, it entails

(d) It is not the case that some P are Q

Invalid = not valid. Is this another case of your reluctance to accept the common usage of negation prefixes? (IN-, UN-, NON-, ANTI-, etc.) like with the previous "unjustified = non justified" confusion?. In any case, whatever it is that you mean by "invalid" over and above not valid. I don't mean that. By "invalid" I mean "not valid" and nothing else.

Well, in that case, fine. I agree. All inductive arguments are not-valid arguments. Or, by obversion, no inductive arguments are valid arguments. (I wish I had thought to say all inductive arguments are non-valid arguments. That would have, perhaps, made it clearer). All arguments are either valid or not valid. But it is not true that all arguments are either valid or invalid. It is analogous to the distinction between LEM, and the law of bi-valence. For all statements S, either S or not-S. But not every statement is either true or false.

Excuse my strict-attention to logical form. But I would think the "not" and the "non" perform different functions. You said that,

"All inductive arguments are non-valid arguments," which means,

All inductive arguments are non-valid (invalid) arguments, which is false,

But are "invalid" and "non-valid" synonymous?

Please stop responding to my posts. I can't stand having my fallacies revealed!

Just to expound on this (and to see how I do),

Terms that apply to deductive arguments are:
1) "Valid"
2) "Invalid"
3) "Sound"
4) "Unsound"
5) "Cogent"
6) "Uncogent"

Terms that apply to inductive arguments are:
1) "Strong"
2) "Weak"
3) "Cogent"
4) "Uncogent"

More thoughts,

Just as "Deductive" and "non-deductive" are collectively exhaustive, so too are "Inductive" and "non-inductive".

Terms that apply to non-deductive arguments are the same terms that apply to inductive arguments.

Terms that apply to non-inductive arguments, however, can include:
1) "Valid"
2) "Invalid"
3) "Sound"
4) "Unsound"
5) "Cogent"
6) "Uncogent"
7) "Weak"
8) "Strong"

because an argument that is a non-inductive argument may either be a deductive argument or a non-deductive argument, but if it is a non-deductive argument, that's not to say it's necessarily an inductive argument.

Well, in that case, fine. I agree. All inductive arguments are not-valid arguments. Or, by obversion, no inductive arguments are valid arguments. (I wish I had thought to say all inductive arguments are non-valid arguments. That would have, perhaps, made it clearer). All arguments are either valid or not valid. But it is not true that all arguments are either valid or invalid. It is analogous to the distinction between LEM, and the law of bi-valence. For all statements S, either S or not-S. But not every statement is either true or false.

(Had I read Extrain's most recent post before this one, I would not have written this post).

lol. But it's not as if "validity is optional" for you--especially when the topic is Logic!:devilish:

Just to expound on this (and to see how I do),

Terms that apply to deductive arguments are:
1) "Valid"
2) "Invalid"
3) "Sound"
4) "Unsound"
5) "Cogent"
6) "Uncogent"

Terms that apply to inductive arguments are:
1) "Strong"
2) "Weak"
3) "Cogent"
4) "Uncogent"

More thoughts,

Just as "Deductive" and "non-deductive" are collectively exhaustive, so too are "Inductive" and "non-inductive".

Terms that apply to non-deductive arguments are the same terms that apply to inductive arguments.

Terms that apply to non-inductive arguments, however, can include:
1) "Valid"
2) "Invalid"
3) "Sound"
4) "Unsound"
5) "Cogent"
6) "Uncogent"
7) "Weak"
8) "Strong"

because an argument that is a non-inductive argument may either be a deductive argument or a non-deductive argument, but if it is a non-deductive argument, that's not to say it's necessarily an inductive argument.

I don't get it. What is it that you agree with, if not that all arguments are valid or invalid?

Just to expound on this (and to see how I do),

Terms that apply to deductive arguments are:
1) "Valid"
2) "Invalid"
3) "Sound"
4) "Unsound"
(5) "Cogent"
6) "Uncogent"

1) "Strong"
2) "Weak"
3) "Cogent"
4) "Uncogent"

More thoughts,
Just as "Deductive" and "non-deductive" are collectively exhaustive, so too are "Inductive" and "non-inductive".

1) "Valid"
2) "Invalid"
3) "Sound"
4) "Unsound"
5) "Cogent"
6) "Uncogent"
7) "Weak"
8) "Strong"

No. "Cogent" and "uncogent" do not apply to deductive arguments--only to (non-deductive) inductive arguments.

I don't get it. What is it that you agree with, if not that all arguments are valid or invalid?

I don't agree that the analogy is apt. Did by "statement" what did you mean? Propositions? I think (excluding problems with various paradoxes notably liar paradoxes) that all propositions are either true or false. Did you mean sentences? Given a pluralistic proposition theory of truth carriers, some sentences are not true or false (because they do not express propositions).

Given a monistic proposition theory of truth carriers (I guess you might accept a such, I'm more inclined to accept a pluralistic theory of truth carriers), then no sentence is true or false.

I meant to make a rude remark. The general idea is that you now respond with a rude remark and we continue exchanging such remarks until the mods get here.

Give an example of a non-deductive non-inductive argument.

You summed up what seems to be the standard opinion around here. Now, will you argue it? It is not surprisingly much easier to sum it up and claim it to be the case/true without arguing it. I think I have done well questioning all positions on this and I don't hold a position on what deductive arguments and inductive arguments are, but Pyrrho offered some good theories last I tried talking to him about it. The underlying quandary is what deductive arguments and inductive arguments are. Then there is the usual reluctance for some reason to apply valid/invalid to inductive/non-deductive arguments.

At least, Pyrrho offered something else than an implicit intention theory like the one Ken seems to accept. Hard to tell from his writing it is.

At least, Pyrrho offered something else than an implicit intention theory like the one Ken seems to accept. Hard to tell from his writing it is.

And there is nothing wrong with saying that your argument is "invalid" or "false." That's part of philosophy. This isn't a politically correct forum.

I thought a cogent argument was an argument where the premises are known to be true.

I don't think we should say that arguments are false.

Knowledge implies truth, but truth doesn't imply knowledge. I agree.

But, I don't know why you wouldn't say, "known to be true," and that wasn't the issue anyhow. I thought you said the term "cogent" doesn't apply to deductive arguments, but the problem I have with that is that the premises of some deductive arguments are known to be true, and even if whether it's known is a contention, you still said, "I would just say 'true,'" and since some premises of deductive arguments are true, it seems to me that you would agree that the term, "cogent" can be applied to deductive arguments.

Knowledge implies truth, but truth doesn't imply knowledge. I agree.

But, I don't know why you wouldn't say, "known to be true," and that wasn't the issue anyhow. I thought you said the term "cogent" doesn't apply to deductive arguments,

Yes, that is the difference between a cogent and a sound argument. The premises of a cogent argument are known true, those of a sound argument are true. So, cogent implies sound, but not conversely.