I never said ALL. Quote me.
I did quote you. So now you are denying you meant that all deductive arguments have true premises, and that all deductive arguments have conclusions that follow from their premises? I see. Pretty lame. What did you mean, then? Explain. And make it good.
But the intention theory does not make the distinction between deduction and induction depend on psychology. The distinction is still logical between whether the argument is conclusive or not. Where intention comes in is in trying to decide whether the argument is deductive or inductive. That is an epistemological issue, not a logical issue. Intention theory does not psychologize logic (Frege's bid bugaboo). It may psychologize the epistemology of logic, though. But is that so bad?
I never said ALL. Once again, quote me where I said ALL.
Edit: still waiting ken.
I think you need to articulate precisely what you mean by "the intention theory", as I do not believe that is what I stated at all.
When speaking with others, one is trying to understand what they mean (well, hopefully!). So that when a person is presenting an argument, one is interested in figuring out what the person means, so that one does not waste time on an argument that is irrelevant to what the person intends. This, however, does not make the argument, in itself, dependent upon intentions, as when trying to understand a mathematical problem someone is telling one about, one needs to understand the person in order to understand what math problem it is, but once one knows this, the persons intentions become irrelevant. 2 + 2 = 4, regardless of anyone's intentions, and arguments of the form[INDENT][INDENT][INDENT][INDENT]If P then Q
Therefore Q[/INDENT][/INDENT][/INDENT][/INDENT]are deductively valid regardless of anyone's intentions.
Looking at your post at
it becomes clear that I am not advocating your "intention theory" at all ("An argument is deductive iff it is intended by the arguer to be deductive."), for the deductive validity of Modus Ponens (the argument form above, for those who don't know) is not in any way dependent upon what someone intends. Modus Ponens is a deductive form of argument, regardless of how anyone intends it to be taken.
Ok. No major disagreements.
But I don't know what "This, however, does not make the argument, in itself, dependent upon intentions" means.
I agree that the argument above is valid (= "deductively valid"), but that does not imply that it is deductive. So, you beg the question when you write "Modus Ponens is a deductive form of argument, regardless of how anyone intends it to be taken.".
This is what is at issue. I'm not endorsing any specific theory. Maybe you have a third theory on the matter? That's good. But it would be better if you told us about it.
Hm, I thought you could have inferred what I meant by my question.
Can you explain why you came to that conclusion in the first place?
Thanks, that clears it up a bit. I still don't quite get it, but I'll do more research.
But I didn't come to the conclusion. I do not accept the analogy, I merely mentioned it because it seems that some people find it convincing (eg Kritikos though to be fair he did not write it at all, I inferred it from some of what he wrote).
Kennethamy is talking about a different intention theory that I am talking about. The one in my essay is not merely methodological (not "epistemological", Ken), as in how to decide whether an argument is deductive or inductive. It is a theory of what a deductive and inductive argument is.
If the argument is deductively valid, then why doesn't that imply it is a deductive argument? How can it be a deductively valid argument, but not be a deductive argument? If someone intends it to be inductive, he has the wrong argument. Suppose I intend an addition to be a subtraction. Would that make the addition a subtraction?
But we already have a theory of that which seems to be satisfactory. A deductive argument is, if correct, a conclusive argument. A non-deductive argument is, if correct, a non-conclusive argument.
Your language use is peculiar. I don't want to discuss this odd view you have about negation suffixes ("-un", "-in" etc.). In this thread "invalid" means "not valid". I stipulate it as I have no patience to go through another case of your (or Ken's) personal language use. (Recall the case with "unjustified" and "not justified"?)
To say of an argument that it's invalid implies that the argument is deductive. To say of an argument that it's not valid implies no such thing.
And yes, as Ken says, I am saying that it's a category mistake to apply the term "invalid" to inductive arguments, for inductive arguments are neither valid nor invalid--only not valid.
Recall the case with "not true" and "false"? False implies not true, but not true doesn't imply false. Same with not valid and invalid. Invalid implies not valid, but not valid doesn't imply invalid. Confusing not valid with invalid is like confusing not true with false.
Because according to the intention theory iff the arguer intended an argument to be inductive, then it is inductive. And some arguers intend that a valid argument is inductive. Thus, there is a valid inductive argument.
The intention theory does not say that only if an argument is intended to be inductive, is it inductive. The intention is a sufficient condition, not a necessary condition. It is not a bi-conditional.
You may want to read my essay again for I clearly stated it was a bi-conditional. All explanations of what X is use a bi-conditional.
You are confusing using the arguer's intention as a means of discovering what type of argument it is, that is, purely as a method, with using the arguer's intentions to explain what type of argument it is. I pointed this out before but you must have missed it or ignored it.
What is the basis for thinking that the intention theory is true? It seems obvious to me that it's false because it confuses intentions with actuality. I may intend to give (for example) a conclusive argument, yet I may fail to actually do what I intend. If I give a non-conclusive argument, then I did not give a conclusive argument, regardless of what I intended to do.
All women are mortal. Socrates is a man; therefore, Socrates is mortal.
Notice that I am not merely trying to provide support for my conclusion. I am trying to provide support so strong that the conclusion is guaranteed; hence, I'm not trying to say it's probable that the conclusion is true but conclusively true.
However, notice that I did not do as I intended. The form is not valid, yet it's a deductive argument, so it's an invalid deductive argument.
However, you say there is no such thing as an invalid deductive argument and that if an argument isn't deductive, then it's inductive, so according to your theory, the argument is an inductive argument.
However, it's not the case that I am merely trying to provide support but rather support so strong that the conclusion is guaranteed.
The intention theory nor the validity theory holds up.
A first simple formulation of the central theses is:
An argument is deductive iff it is intended by the arguer to be deductive.
An argument is inductive iff it is intended by the arguer to be inductive.
One need only briefly consider the implications of this flaky theory to realize that it's flawed. Maybe we should call this the Humpty Dumpty Theory of Arguments since it so closely resembles the flaky theory that words mean only what people say they mean.
A deductive argument is a deductive argument independent of what an arguer intends; furthermore, an inductive argument is an inductive argument independent of what an arguer intends. Yes, we cannot sometimes tell whether an argument is deductive or inductive if not privy to the arguer's intentions, but that is another matter entirely-truth is independent of knowledge ya know. Of course, I don't expect you to take my word for it quite yet, as I am merely denying that what you say is true and setting you straight on what is true.
Of course, I can do a little bit more than that. I can also help you get a handle on your mistake by encouraging you to use a little bit of reasoning as you explain to me why a sensible person would even think that what you say is true. But, what I don't need are links. I don't need inept sources, and I don't need to wade through your essays that are mistake-ridden-what is a sound inductive argument anyway?
What you need to do is step up to the plate and, in your own words, concisely explain why you think a kind of argument (deductive or inductive) is dependent on the intentions of the arguer. I have already pointed out the confusion upon which this flakiness is based. The theory (if we can call it that) confuses intentions with actuality. Sometimes, we don't actually wind up with what we intend on winding up with, and it's this very simplistic notion that is at the heart of my objection.
By the way, there's a difference between "arrogance" and "conceitedness." You may not care about others, but your condescending attitude is unwelcome, and it's far more inappropriate than any occasional thread derailment.