# Non-deductive VERSUS Inductive

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3. » Non-deductive VERSUS Inductive

Tue 6 Apr, 2010 09:44 am
What difference, if any, is there between a non-deductive argument and an inductive argument?

kennethamy

Tue 6 Apr, 2010 10:23 am
@fast,
fast;148799 wrote:
What difference, if any, is there between a non-deductive argument and an inductive argument?

Sometimes, the term "inductive argument" is use to refer only to arguments by enumeration. That is, arguments of the type, S is an x and S is y, S(1) is an x, and S(1) is y...., therefore, all S's are Y's. But non-deductive arguments are arguments whose premises constitute only support for the conclusion, and do not guarantee the truth of the conclusion. So, all inductive arguments are non-deductive arguments, but not conversely. (When Hume, for example talks about inductive arguments, he refers to enumerative induction. (Sometimes also called, "inductive generalization").

fast

Tue 6 Apr, 2010 10:38 am
@kennethamy,
[QUOTE=kennethamy;148809]So, all inductive arguments are non-deductive arguments, but not conversely.[/QUOTE]I suspected that, but I was hesitant to say it, since I had no support for saying it. I also suspect that deductive arguments and inductive arguments are not collectively exhaustive categories of arguments. Many non-deductive arguments are inductive arguments, but some non-deductive arguments are neither deductive arguments nor inductive arguments. There, I said it, but this brings me back to where I often find myself: having the right answer and no good argument for giving another a reason for believing it.

kennethamy

Tue 6 Apr, 2010 10:49 am
@fast,
fast;148815 wrote:
I suspected that, but I was hesitant to say it, since I had no support for saying it. I also suspect that deductive arguments and inductive arguments are not collectively exhaustive categories of arguments. Many non-deductive arguments are inductive arguments, but some non-deductive arguments are neither deductive arguments nor inductive arguments. There, I said it, but this brings me back to where I often find myself: having the right answer and no good argument for giving another a reason for believing it.

Well, yes. As I pointed out in the earlier post, if, by "inductive argument" you mean only an inductive generalization, then some non-deductive argument are not inductive arguments. For example, arguments by analogy, or deductive nomological explanations. Those examples are examples of non-inductive arguments which are not deductive either.

Emil

Tue 6 Apr, 2010 01:14 pm
@kennethamy,
kennethamy;148809 wrote:
Sometimes, the term "inductive argument" is use to refer only to arguments by enumeration. That is, arguments of the type, S is an x and S is y, S(1) is an x, and S(1) is y...., therefore, all S's are Y's. But non-deductive arguments are arguments whose premises constitute only support for the conclusion, and do not guarantee the truth of the conclusion. So, all inductive arguments are non-deductive arguments, but not conversely. (When Hume, for example talks about inductive arguments, he refers to enumerative induction. (Sometimes also called, "inductive generalization").

It follows from how you use the words that all deductive arguments are valid, and that all inductive arguments are invalid. You have the same problem with your position, if it is your position, which you had last time we discussed this. That was in the deductive/inductive thread.

fast

Tue 6 Apr, 2010 01:19 pm
@Emil,
Emil;148862 wrote:
It follows from how you use the words that all deductive arguments are valid, and that all inductive arguments are invalid. You have the same problem with your position, if it is your position, which you had last time we discussed this. That was in the deductive/inductive thread.

How does it follow?

kennethamy

Tue 6 Apr, 2010 01:32 pm
@Emil,
Emil;148862 wrote:
It follows from how you use the words that all deductive arguments are valid, and that all inductive arguments are invalid. You have the same problem with your position, if it is your position, which you had last time we discussed this. That was in the deductive/inductive thread.

Could you show how that is true? My view is that if an argument is valid then it is deductive, but not conversely. In any case, my reply was here was that although all inductive arguments are non-deductive, some non-deductive arguments are not inductive.

fast

Tue 6 Apr, 2010 01:38 pm
@kennethamy,
kennethamy;148817 wrote:
Well, yes. As I pointed out in the earlier post, if, by "inductive argument" you mean only an inductive generalization, then some non-deductive argument are not inductive arguments. For example, arguments by analogy, or deductive nomological explanations. Those examples are examples of non-inductive arguments which are not deductive either.

I do my best to make sure that what I mean matches what the word I use means. I want to make sure that what you're saying doesn't imply that "inductive argument" is ambiguous, for if it is ambiguous, and if it also does mean something else, I need to know.

kennethamy

Tue 6 Apr, 2010 01:42 pm
@fast,
fast;148870 wrote:
I do my best to make sure that what I mean matches what the word I use means. I want to make sure that what you're saying doesn't imply that "inductive argument" is ambiguous, for if it is ambiguous, and if it also does mean something else, I need to know.

As I said, some people use the term, "inductive argument" to mean only enumerative induction. Some just use it to mean the same as "non-deductive argument". Whether that makes the term "ambiguous", I'll leave it for you to decide.

fast

Tue 6 Apr, 2010 01:50 pm
@kennethamy,
[QUOTE=kennethamy;148873]As I said, some people use the term, "inductive argument" to mean only enumerative induction. Some just use it to mean the same as "non-deductive argument". Whether that makes the term "ambiguous", I'll leave it for you to decide.[/QUOTE]And people use the term, "free will" to mean all sorts of things, but "free will" doesn't mean all sorts of things. If you're meaning to imply that "inductive argument" can appropriately be used to mean either, then whether or not "deductive argument" and "inductive argument" is collectively exhaustive hinges on which use of the term "inductive argument" is being used.

kennethamy

Tue 6 Apr, 2010 01:54 pm
@fast,
fast;148875 wrote:
And people use the term, "free will" to mean all sorts of things, but "free will" doesn't mean all sorts of things. If you're meaning to imply that "inductive argument" can appropriately be used to mean either, then whether or not "deductive argument" and "inductive argument" is collectively exhaustive hinges on which use of the term "inductive argument" is being used.

I guess that is right. But I don't think that too much should be made of it. It is, after all, only a verbal matter. Which notation is better seems to me a pragmatic matter. I think that the use of "non-deductive" as distinct from inductive makes things a little clearer.

Emil

Tue 6 Apr, 2010 03:11 pm
@fast,
What a term means is what people use it to mean. If people use it to mean two different things, then that is what it is, and that is what "ambiguous" means. As Ken says people use "inductive argument" in the two meanings vaguely described by him.

kennethamy

Tue 6 Apr, 2010 03:36 pm
@Emil,
Emil;148897 wrote:
What a term means is what people use it to mean. If people use it to mean two different things, then that is what it is, and that is what "ambiguous" means. As Ken says people use "inductive argument" in the two meanings vaguely described by him.

Don't see what was vague about it. It seemed pretty exact to me.

a. Inductive argument= inductive generalization.
b, Inductive argument= any non-deductive argument.

So, b implies a, but a does not imply b. What is vague about that?

Emil

Tue 6 Apr, 2010 05:23 pm
@kennethamy,
kennethamy;148900 wrote:
Don't see what was vague about it. It seemed pretty exact to me.

a. Inductive argument= inductive generalization.
b, Inductive argument= any non-deductive argument.

So, b implies a, but a does not imply b. What is vague about that?

Your characterization of "non-deductive argument" is vague.

Quote:
But non-deductive arguments are arguments whose premises constitute only support for the conclusion, and do not guarantee the truth of the conclusion.

How is this to be understood? You said that there are no valid inductive arguments. Presumably there are invalid deductive arguments and they "do not guarantee the truth of the conclusion", so your position is inconsistent unless you have some vague idea of the above in mind. I find that the most plausible reading of what you wrote.

kennethamy

Tue 6 Apr, 2010 05:36 pm
@Emil,
Emil;148951 wrote:
Your characterization of "non-deductive argument" is vague.

How is this to be understood? You said that there are no valid inductive arguments. Presumably there are invalid deductive arguments and they "do not guarantee the truth of the conclusion", so your position is inconsistent unless you have some vague idea of the above in mind. I find that the most plausible reading of what you wrote.

Well, we all know what a deductive argument is (I hope). Any argument that is not a deductive argument is non-deductive.

It does not follow that because there are no valid inductive arguments, that there are invalid deductive arguments. There are, of course, but it does not follow. Inductive arguments are neither valid nor are they invalid. Some have held that an invalid deductive argument might be a strong inductive argument. But that seems to me to be false. A deductive argument that commits the fallacy of affirming the antecedent is not a strong inductive argument. It is just an invalid deductive argument.

fast

Tue 6 Apr, 2010 07:47 pm
@kennethamy,
kennethamy;148959 wrote:
Inductive arguments are neither valid nor are they invalid.

Exactly! It's true that they are not valid, but it's false that they are invalid.

Emil

Tue 6 Apr, 2010 07:52 pm
@kennethamy,
kennethamy;148959 wrote:
Well, we all know what a deductive argument is (I hope). Any argument that is not a deductive argument is non-deductive.

It does not follow that because there are no valid inductive arguments, that there are invalid deductive arguments. There are, of course, but it does not follow..

That depends on what you mean by "follow". The material conditional is true. That's one sense of follow. I'm inclined to believe that that material conditional is logically necessary. That implies that there is also a logical implication connection. That's another sense of "follow". If you have some other sense in mind, you'd need to tell me about it.

Quote:
Inductive arguments are neither valid nor are they invalid.

I disagree. Why you do think they are neither valid or invalid?

The reason for believing it is pretty straightforward. A common definition of valid argument is:
[INDENT]Validity. An argument is valid iff it is impossible that (the conclusion is not the case and all the premises are the case)
[/INDENT]It follows from that definition (which is a logical equivalence too, so are all definitions in a sense) and any particular inductive argument that it is either valid or invalid.

Some people keep claiming this is somehow a category error, and that "valid" and "valid" somehow cannot meaningfully be applied to inductive arguments. That is bullocks. It obviously can. It would be extremely hard-headed to read the above and keep claiming that it is meaningless. If a person does that, I must confess that I cannot reason with him. (Paraphrasing Hume.)

Quote:
Some have held that an invalid deductive argument might be a strong inductive argument. But that seems to me to be false. A deductive argument that commits the fallacy of affirming the antecedent is not a strong inductive argument. It is just an invalid deductive argument

You didn't give any reason to believe that the universal conditional is false. You mentioned one case where it is false.

---------- Post added 04-07-2010 at 03:53 AM ----------

fast;149026 wrote:

Exactly! It's true that they are not valid, but it's false that they are invalid.

You going to try claiming that it is somehow a category error again...?

kennethamy

Wed 7 Apr, 2010 09:47 am
@Emil,
Emil;149031 wrote:
That depends on what you mean by "follow". The material conditional is true. That's one sense of follow. I'm inclined to believe that that material conditional is logically necessary. That implies that there is also a logical implication connection. That's another sense of "follow". If you have some other sense in mind, you'd need to tell me about it.

I disagree. Why you do think they are neither valid or invalid?

The reason for believing it is pretty straightforward. A common definition of valid argument is:[INDENT]Validity. An argument is valid iff it is impossible that (the conclusion is not the case and all the premises are the case)
[/INDENT]It follows from that definition (which is a logical equivalence too, so are all definitions in a sense) and any particular inductive argument that it is either valid or invalid.

Some people keep claiming this is somehow a category error, and that "valid" and "valid" somehow cannot meaningfully be applied to inductive arguments. That is bullocks. It obviously can. It would be extremely hard-headed to read the above and keep claiming that it is meaningless. If a person does that, I must confess that I cannot reason with him. (Paraphrasing Hume.)

You didn't give any reason to believe that the universal conditional is false. You mentioned one case where it is false.

---------- Post added 04-07-2010 at 03:53 AM ----------

You going to try claiming that it is somehow a category error again...?

It simply does not seem to me that we should hold up deductive arguments as the standard for judging non-deductive arguments, and when you state that inductive arguments are invalid, that is what you are doing. That inductive arguments are not valid seems to me true, but not that they are invalid, since if it makes sense to say of some inductive arguments that they are "invalid", then shouldn't it made sense to say of them that they are "valid" too? After all, given your (correct) definition of "validity" it is true that inductive arguments which cannot meet that definition are not valid. But what makes you think that if they are not valid, then they are invalid? All arguments are, of course, either valid or not valid, but only deductive arguments are either valid or invalid.

Extrain

Wed 7 Apr, 2010 04:23 pm
@kennethamy,
Emil;149031 wrote:
Some people keep claiming this is somehow a category error, and that "valid" and "valid" somehow cannot meaningfully be applied to inductive arguments. That is bullocks. It obviously can. It would be extremely hard-headed to read the above and keep claiming that it is meaningless. If a person does that, I must confess that I cannot reason with him. (Paraphrasing Hume.)

...which was precisely Hume's error. Hume was dense for thinking inductive arguments have to meet the standards of validity set up by deductive arguments.

If the only acceptable form of reasoning is deductive reasoning, then all we have to do is disagree with Hume by reading his argument right back to him.

"No inductive argument is a valid or invalid kind of argument.
Therefore, all inductive arguments are invalid."

This argument, itself, is invalid--and obviously so.

Therefore, Hume was wrong.

Emil

Wed 7 Apr, 2010 07:53 pm
@kennethamy,
kennethamy;149233 wrote:
It simply does not seem to me that we should hold up deductive arguments as the standard for judging non-deductive arguments, and when you state that inductive arguments are invalid, that is what you are doing. That inductive arguments are not valid seems to me true, but not that they are invalid, since if it makes sense to say of some inductive arguments that they are "invalid", then shouldn't it made sense to say of them that they are "valid" too? After all, given your (correct) definition of "validity" it is true that inductive arguments which cannot meet that definition are not valid. But what makes you think that if they are not valid, then they are invalid? All arguments are, of course, either valid or not valid, but only deductive arguments are either valid or invalid.

I didn't say that we should "hold up deductive arguments as the standard for judging non-deductive arguments". That sounds like some premature criticism of inductive reasoning. There was not much normative in my post above other than one ought to stop claiming that inductive arguments are not valid or invalid. 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?. 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.

Or if you really, really want to stick to your terms. Then fine, let's say that all arguments are either valid or not valid. Now posing these questions in the same form as before gives grammatically odd sentences but surely they are understandable.

Questions:
[INDENT]1. Are there valid inductive arguments?
2. Are there not valid inductive arguments?
3. Are there valid deductive arguments?
4. Are there not valid deductive arguments?
[/INDENT]Depending on how you define "deductive argument" and "inductive argument" you will give different answers.

---------- Post added 04-08-2010 at 03:54 AM ----------

Extrain;149397 wrote:
...which was precisely Hume's error. Hume was dense for thinking inductive arguments have to meet the standards of validity set up by deductive arguments.

If the only acceptable form of reasoning is deductive reasoning, then all we have to do is disagree with Hume by reading his argument right back to him.

"No inductive argument is a valid or invalid kind of argument.
Therefore, all inductive arguments are invalid."

This argument, itself, is invalid--and obviously so.

Therefore, Hume was wrong.

Whatever. (Symbols...)

1. Philosophy Forum
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3. » Non-deductive VERSUS Inductive