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Logic: Perscriptive, descriptive, both or neither?

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So I've been considering a question tonight and I figured I'd send it out there into the interwebs. I've begun reading HWB Joseph's treatise and course on Logic "Introduction To Logic". On the outset he makes the claim that logic is not so much the science of deciding what is rational, but rational, but rather what rational thought seems to mean to human beings. "Logic, then, is the science which studies the general principles in accordance with which we think about things whatever things they may be." (Joseph, pg 3)

Rand infamously describes logic as the art of non-contradictory identification.

I am wondering if these two views are homogeneous or antagonistic to one another? I take Joseph's claim to be one of descriptive knowledge: we figure out what laws seem to govern our thought and we write on these. Rand can be viewed as perscriptive account. We must learn how to think logically, that perhaps we are wrong in our intuitions of what is logical and what is not. It is the art of non-contradictory identification. This seems to imply many may make contradictory identifications.

Now of course Joseph is not here saying that human beings are incapable of thinking irrationally, however I think this is a rather normative theory. It tries to line up rules of logic with the rules of human thought. These might not be in conflict, but they may indeed be. I know plenty of individuals who think they are perfectly justified in their inference to something such as God's existence based not on what we identify as logical rules but on faith.

Perhaps I just need some coffee.

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So I've been considering a question tonight and I figured I'd send it out there into the interwebs. I've begun reading HWB Joseph's treatise and course on Logic "Introduction To Logic". On the outset he makes the claim that logic is not so much the science of deciding what is rational, but rational, but rather what rational thought seems to mean to human beings. "Logic, then, is the science which studies the general principles in accordance with which we think about things whatever things they may be." (Joseph, pg 3)

Rand infamously describes logic as the art of non-contradictory identification.

I am wondering if these two views are homogeneous or antagonistic to one another? I take Joseph's claim to be one of descriptive knowledge: we figure out what laws seem to govern our thought and we write on these. Rand can be viewed as perscriptive account. We must learn how to think logically, that perhaps we are wrong in our intuitions of what is logical and what is not. It is the art of non-contradictory identification. This seems to imply many may make contradictory identifications.

Now of course Joseph is not here saying that human beings are incapable of thinking irrationally, however I think this is a rather normative theory. It tries to line up rules of logic with the rules of human thought. These might not be in conflict, but they may indeed be. I know plenty of individuals who think they are perfectly justified in their inference to something such as God's existence based not on what we identify as logical rules but on faith.

Perhaps I just need some coffee.

Going by his statement and your 'take' on him, I'd say Joseph is the one being prescriptive, and Rand descriptive (more precisely, definitive.)

How does logic become the study of general principles?

General principles are derived from logic, deduction and induction, not the other way round.

Again, "It tries to line up rules of logic with the rules of human thought" is also back to front, I think.

Interesting.

Yes coffee helps, I find.

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To keep my response brief I will launch straight into Objectivist jargon.

By the "spiral theory of knowledge" both perspectives are necessary. In an original position of complete ignorance the first thing to do is to survey the field. This is the descriptive phase of knowing about knowing. Then distinctions about better and worse can be made which enables the prescriptive phase.

This is also related to the "principle of two definitions" in that a normative definition is hierarchically later than a descriptive definition. Often when definitions are revised due to an expanded context of knowledge the earlier definition is abandoned but in normative philosophizing it is logically necessary to keep the earlier definition. To do otherwise would be to simply assume the normative conclusions.

See Peikoff's "Unity" course (notes in my sig).

In the lecture, Peikoff claims that the two definitions principle should not be applied to logic itself. I think I would have to disagree.

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H.W.B. Joseph notes that the sciences provide material for figuring out how to reason properly because they are the products of our clearest, most correct reasoning by intellects most involved with the relevant facts and therefore most likely to produce correct conclusions.

In order for reasoning to be "proper", it must follow rules like the law of non-contradiction and employ methods

But in order to know anything about non-contradiction you have to know something about propositions and arguments.

I mention this because Joseph focuses on "general principles" in his definition, which obviously includes the laws of logic.

And in order to have any idea of "proper reasoning", one must know that there is an element of choice in reasoning and that is possible to err.

I do not think Peikoff's principle of two definitions applies to logic.

Joseph's definition is not an A1 definition. A1 is supposed to be a permanent, objective demarcation. However part of objectivity involves following certain rules of method, such as can be found by studying logic. Joseph's definition is most certainly prescriptive.

Joseph vs Rand:

Joseph's definition addresses the study of how to reason properly. Rand's definition addresses the act of reasoning properly itself. Both are normative. Joseph's is normative in that it prescribes studying how to reason properly. Rand's is normative in that it prescribes non-contradiction, which has been a guiding first principle in logic since the ancients.

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H.W.B. Joseph notes that the sciences provide material for figuring out how to reason properly because they are the products of our clearest, most correct reasoning by intellects most involved with the relevant facts and therefore most likely to produce correct conclusions.

In order for reasoning to be "proper", it must follow rules like the law of non-contradiction and employ methods

But in order to know anything about non-contradiction you have to know something about propositions and arguments.

I mention this because Joseph focuses on "general principles" in his definition, which obviously includes the laws of logic.

And in order to have any idea of "proper reasoning", one must know that there is an element of choice in reasoning and that is possible to err.

We do need to know about choice, but that is axiomatic and implicit in all thought. We need to know about error, but we knew about error and lying and false assertions long before taking up a formal study of propositions and deductions. We do not need to know the principles of proper reasoning to discover the principles of proper reasoning. That is a vicious circle no one could ever break into.

The following paragraphs from Joseph (both chapter 1) himself will address this.

What has been now said will serve to remove an objection which

Locke brought against the study of Logic. "God", says Locke ^,

"has not been so sparing to men, to make them barely two-legged

creatures, and left it to Aristotle to make them rational." He is

urging that men thought rationally, or logically, i. e. in accordance

with the principles that Logic discovers to regulate all sound thought,

long before those principles were recognized; and that this is still

so with each of us; we do not therefore need Logic to teach us how

to think. That is quite true, and would be a pertinent criticism

against any one who pretended that no one could think rationally

without studying Logic ; but it is not the business of Logic to make

men rational, but rather to teach them in what their being rational

consists. And this they could never learn, if they were not rational

first; just as a man could never study (say) the principles of volun-

tary motion, if he was not first accustomed to move his limbs as

he willed. Had God made men barely two-legged creatures, Aris-

totle would in vain have taught them to be rational, for they would

not have understood his teaching.

^ Essay, Bk. IV. c. xvii. ยง 4

If now we ask for a definition of Logic, to keep before our minds

in the following chapters, perhaps it is simplest and least objection-

able to call it the Science, or the Study, of Thought ; for to say of

the Formal Principles of Thought might imply both that there were

sciences which did not seek for principles, and that the "form" of

thought can be studied without reference to differences in the matter

of it ; neither of which things is true.

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We do not need to know the principles of proper reasoning to discover the principles of proper reasoning. That is a vicious circle no one could ever break into.

which is why he suggests (in the introduction) that we study the best examples of reasoning

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which is why he suggests (in the introduction) that we study the best examples of reasoning

But what makes the sciences stand out as "best" examples? Simply examining their methods tells us nothing without some prior idea of what a "better" method is.

Fortunately, there is a prior idea available to distinguish between better and worse methods, and that idea is 'truth'. Sciences produce results in the form of calculations, predictions and practical applications. Success there establishes truth between thought and fact by the correspondence principle. It is then induced that the success in producing truths in the sciences has a common cause in the common methods of thought employed. The concept of method could be formed from instances of methods for successful wine making, fishing and farming. That the concept of method could legitimately be extended to thought was first shown by the ancient geometers. A proof by successful action is form of reduction to the perceptual level, and is the implicit beginning of the concept of objectivity.

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But what makes the sciences stand out as "best" examples? Simply examining their methods tells us nothing without some prior idea of what a "better" method is...

(Nice outline for inducing "method" btw)

I think it was obvious to Joseph that "truth" distinguishes better methods from worse ones, though Joseph never quite seems to tell us what he thinks it is.

But I think that "truth" is worth further discussing because it has bearing on norms related to logic.

A popular view of "truth" was "correspondence", but this leads to problems that should have been obvious to any polymath of the 19th century.

1) Not all sciences afford calculations and predictions. Some things are known to be true through other means. Biological classification is about conceptual hierarchy. Anatomy and physiology are about the structure and function of living systems and their components. They do not afford corresponds tests in the way that physics does. But their propositions are true nonetheless. How? The context of the discoveries.

2) Furthermore if one doesn't keep context, the demand for "correspondence" becomes a demand for omniscience. Does Galileo's law of fall "correspond" to all falls? What about a steel ball bearing subject to powerful magnets?

So in addition to traditional standards such as logical validity and coherence, we need the epistemic norm of context-keeping.

A class of norms pops right out of this discussion. What sorts of norms are coherence and context-keeping? What do we need them for? We need them to help distinguish between a proper integration and a misintegration. They're norms of integration.

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