inquiry là gì

A question mark

An inquiry (also spelled as enquiry in British English)[a] is any process that has the aim of augmenting knowledge, resolving doubt, or solving a problem. A theory of inquiry is an tài khoản of the various types of inquiry and a treatment of the ways that each type of inquiry achieves its aim.

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Inquiry theories[edit]


When three terms are so sánh related to lớn one another that the last is wholly contained in the middle and the middle is wholly contained in or excluded from the first, the extremes must admit of perfect syllogism. By 'middle term' I mean that which both is contained in another and contains another in itself, and which is the middle by its position also; and by 'extremes' (a) that which is contained in another, and (b) that in which another is contained. For if A is predicated of all B, and B of all C, A must necessarily be predicated of all C. ... I Điện thoại tư vấn this kind of figure the First. (Aristotle, Prior Analytics, 1.4)


Inductive reasoning consists in establishing a relation between one extreme term and the middle term by means of the other extreme; for example, if B is the middle term of A and C, in proving by means of C that A applies to lớn B; for this is how we effect inductions. (Aristotle, Prior Analytics, 2.23)


The locus classicus for the study of abductive reasoning is found in Aristotle's Prior Analytics, Book 2, Chapt. 25. It begins this way:

We have Reduction (απαγωγη, abduction):

  1. When it is obvious that the first term applies to lớn the middle, but that the middle applies to lớn the last term is not obvious, yet is nevertheless more probable or not less probable phàn nàn the conclusion;
  2. Or if there are not many intermediate terms between the last and the middle;

For in all such cases the effect is to lớn bring us nearer to lớn knowledge.

By way of explanation, Aristotle supplies two very instructive examples, one for each of the two varieties of abductive inference steps that he has just described in the abstract:

  1. For example, let A stand for "that which can be taught", B for "knowledge", and C for "morality". Then that knowledge can be taught is evident; but whether virtue is knowledge is not clear. Then if BC is not less probable or is more probable phàn nàn AC, we have reduction; for we are nearer to lớn knowledge for having introduced an additional term, whereas before we had no knowledge that AC is true.
  2. Or again we have reduction if there are not many intermediate terms between B and C; for in this case too we are brought nearer to lớn knowledge. For example, suppose that D is "to square", E "rectilinear figure", and F "circle". Assuming that between E and F there is only one intermediate term — that the circle becomes equal to lớn a rectilinear figure by means of lunules — we should approximate to lớn knowledge. (Aristotle, "Prior Analytics", 2.25, with minor alterations)

Aristotle's latter variety of abductive reasoning, though it will take some explaining in the sequel, is well worth our contemplation, since it hints already at streams of inquiry that course well beyond the syllogistic source from which they spring, and into regions that Peirce will explore more broadly and deeply.

Inquiry in the pragmatic paradigm[edit]

In the pragmatic philosophies of Charles Sanders Peirce, William James, John Dewey, and others, inquiry is closely associated with the normative science of logic. In its inception, the pragmatic model or theory of inquiry was extracted by Peirce from its raw materials in classical logic, with a little bit of help from Kant, and refined in parallel with the early development of symbolic logic by Boole, De Morgan, and Peirce himself to lớn address problems about the nature and conduct of scientific reasoning. Borrowing a brace of concepts from Aristotle, Peirce examined three fundamental modes of reasoning that play a role in inquiry, commonly known as abductive, deductive, and inductive inference.

In rough terms, abduction is what we use to lớn generate a likely hypothesis or an initial diagnosis in response to lớn a phenomenon of interest or a problem of concern, while deduction is used to lớn clarify, to lớn derive, and to lớn explicate the relevant consequences of the selected hypothesis, and induction is used to lớn test the sum of the predictions against the sum of the data. It needs to lớn be observed that the classical and pragmatic treatments of the types of reasoning, dividing the generic territory of inference as they vì thế into three special parts, arrive at a different characterization of the environs of reason phàn nàn vì thế those accounts that count only two.

These three processes typically operate in a cyclic fashion, systematically operating to lớn reduce the uncertainties and the difficulties that initiated the inquiry in question, and in this way, to lớn the extent that inquiry is successful, leading to lớn an increase in knowledge or in skills.

In the pragmatic way of thinking everything has a purpose, and the purpose of each thing is the first thing we should try to lớn note about it.[2] The purpose of inquiry is to lớn reduce doubt and lead to lớn a state of belief, which a person in that state will usually Điện thoại tư vấn knowledge or certainty. As they contribute to lớn the over of inquiry, we should appreciate that the three kinds of inference describe a cycle that can be understood only as a whole, and none of the three makes complete sense in isolation from the others. For instance, the purpose of abduction is to lớn generate guesses of a kind that deduction can explicate and that induction can evaluate. This places a mild but meaningful constraint on the production of hypotheses, since it is not just any wild guess at explanation that submits itself to lớn reason and bows out when defeated in a match with reality. In a similar fashion, each of the other types of inference realizes its purpose only in accord with its proper role in the whole cycle of inquiry. No matter how much it may be necessary to lớn study these processes in abstraction from each other, the integrity of inquiry places strong limitations on the effective modularity of its principal components.

In Logic: The Theory of Inquiry, John Dewey defined inquiry as "the controlled or directed transformation of an indeterminate situation into one that is so sánh determinate in its constituent distinctions and relations as to lớn convert the elements of the original situation into a unified whole".[3] Dewey and Peirce's conception of inquiry extended beyond a system of thinking and incorporated the social nature of inquiry. These ideas are summarize in the notion Community of inquiry.[4][5][6]

Art and science of inquiry[edit]

For our present purposes, the first feature to lớn note in distinguishing the three principal modes of reasoning from each other is whether each of them is exact or approximate in character. In this light, deduction is the only one of the three types of reasoning that can be made exact, in essence, always deriving true conclusions from true premises, while abduction and induction are unavoidably approximate in their modes of operation, involving elements of fallible judgment in practice and inescapable error in their application.

The reason for this is that deduction, in the ideal limit, can be rendered a purely internal process of the reasoning agent, while the other two modes of reasoning essentially demand a constant interaction with the outside world, a source of phenomena and problems that will no doubt continue to lớn exceed the capacities of any finite resource, human or machine, to lớn master. Situated in this larger reality, approximations can be judged appropriate only in relation to lớn their context of use and can be judged fitting only with regard to lớn a purpose in view.

A parallel distinction that is often made in this connection is to lớn Điện thoại tư vấn deduction a demonstrative khuông of inference, while abduction and induction are classed as non-demonstrative forms of reasoning. Strictly speaking, the latter two modes of reasoning are not properly called inferences at all. They are more lượt thích controlled associations of words or ideas that just happen to lớn be successful often enough to lớn be preserved as useful heuristic strategies in the repertoire of the agent. But non-demonstrative ways of thinking are inherently subject to lớn error, and must be constantly checked out and corrected as needed in practice.

In classical terminology, forms of judgment that require attention to lớn the context and the purpose of the judgment are said to lớn involve an element of "art", in a sense that is judged to lớn distinguish them from "science", and in their renderings as expressive judgments to lớn implicate arbiters in styles of rhetoric, as contrasted with logic.

In a figurative sense, this means that only deductive logic can be reduced to lớn an exact theoretical science, while the practice of any empirical science will always remain to lớn some degree an art.

Zeroth order inquiry[edit]

Many aspects of inquiry can be recognized and usefully studied in very basic logical settings, even simpler phàn nàn the level of syllogism, for example, in the realm of reasoning that is variously known as Boolean algebra, propositional calculus, sentential calculus, or zeroth-order logic. By way of approaching the learning curve on the gentlest availing slope, we may well begin at the level of zeroth-order inquiry, in effect, taking the syllogistic approach to lớn inquiry only so sánh far as the propositional or sentential aspects of the associated reasoning processes are concerned. One of the bonuses of doing this in the context of Peirce's logical work is that it provides us with doubly instructive exercises in the use of his logical graphs, taken at the level of his so-called "alpha graphs".

In the case of propositional calculus or sentential logic, deduction comes down to lớn applications of the transitive law for conditional implications and the approximate forms of inference huyệt on the properties that derive from these. In describing the various types of inference I will employ a few old "terms of art" from classical logic that are still of use in treating these kinds of simple problems in reasoning.

Deduction takes a Case, the minor premise
and combines it with a Rule, the major premise
to arrive at a Fact, the demonstrative conclusion
Induction takes a Case of the khuông
and matches it with a Fact of the khuông
to infer a Rule of the khuông
Abduction takes a Fact of the khuông
and matches it with a Rule of the khuông
to infer a Case of the khuông

For ease of reference, Figure 1 and the Legend beneath it summarize the classical terminology for the three types of inference and the relationships among them.

o-------------------------------------------------o | | | Z | | o | | |\ | | | \ | | | \ | | | \ | | | \ | | | \ R U L E | | | \ | | | \ | | F | \ | | | \ | | A | \ | | | o Y | | C | / | | | / | | T | / | | | / | | | / | | | / C A S E | | | / | | | / | | | / | | | / | | |/ | | o | | X | | | | Deduction takes a Case of the khuông X → Y, | | matches it with a Rule of the khuông Y → Z, | | then adverts to lớn a Fact of the khuông X → Z. | | | | Induction takes a Case of the khuông X → Y, | | matches it with a Fact of the khuông X → Z, | | then adverts to lớn a Rule of the khuông Y → Z. | | | | Abduction takes a Fact of the khuông X → Z, | | matches it with a Rule of the khuông Y → Z, | | then adverts to lớn a Case of the khuông X → Y. | | | | Even more succinctly: | | | | Abduction Deduction Induction | | | | Premise: Fact Case Case | | Premise: Rule Rule Fact | | Outcome: Case Fact Rule | | | o-------------------------------------------------o Figure 1. Elementary Structure and Terminology

In its original usage a statement of Fact has to lớn vì thế with a deed done or a record made, that is, a type of sự kiện that is openly observable and not riddled with speculation as to lớn its very occurrence. In contrast, a statement of Case may refer to lớn a hidden or a hypothetical cause, that is, a type of sự kiện that is not immediately observable to lớn all concerned. Obviously, the distinction is a rough one and the question of which mode applies can depend on the points of view that different observers adopt over time. Finally, a statement of a Rule is called that because it states a regularity or a regulation that governs a whole class of situations, and not because of its syntactic khuông. So far in this discussion, all three types of constraint are expressed in the khuông of conditional propositions, but this is not a fixed requirement. In practice, these modes of statement are distinguished by the roles that they play within an argument, not by their style of expression. When the time comes to lớn branch out from the syllogistic framework, we will find that propositional constraints can be discovered and represented in arbitrary syntactic forms.

Example of inquiry[edit]

Examples of inquiry, that illustrate the full cycle of its abductive, deductive, and inductive phases, and yet are both concrete and simple enough to lớn be suitable for a first (or zeroth) exposition, are somewhat rare in Peirce's writings, and so sánh let us draw one from the work of fellow pragmatician John Dewey, analyzing it according to lớn the model of zeroth-order inquiry that we developed above.

A man is walking on a warm day. The sky was clear the last time he observed it; but presently he notes, while occupied primarily with other things, that the air is cooler. It occurs to lớn him that it is probably going to lớn rain; looking up, he sees a dark cloud between him and the sun, and he then quickens his steps. What, if anything, in such a situation can be called thought? Neither the act of walking nor the noting of the cold is a thought. Walking is one direction of activity; looking and noting are other modes of activity. The likelihood that it will rain is, however, something suggested. The pedestrian feels the cold; he thinks of clouds and a coming shower. (John Dewey, How We Think, 1910, pp. 6-7).

Once over quickly[edit]

Let's first give Dewey's example of inquiry in everyday life the quick once over, hitting just the high points of its analysis into Peirce's three kinds of reasoning.

Abductive phase[edit]

In Dewey's "Rainy Day" or "Sign of Rain" story, we find our peripatetic hero presented with a surprising Fact:

  • Fact: C → A, In the Current situation the Air is cool.

Responding to lớn an intellectual reflex of puzzlement about the situation, his resource of common knowledge about the world is impelled to lớn seize on an approximate Rule:

  • Rule: B → A, Just Before it rains, the Air is cool.

This Rule can be recognized as having a potential relevance to lớn the situation because it matches the surprising Fact, C → A, in its consequential feature A.

All of this suggests that the present Case may be one in which it is just about to lớn rain:

  • Case: C → B, The Current situation is just Before it rains.

The whole mental performance, however automatic and semi-conscious it may be, that leads up from a problematic Fact and a previously settled knowledge base of Rules to lớn the plausible suggestion of a Case mô tả tìm kiếm, is what we are calling an abductive inference.

Deductive phase[edit]

The next phase of inquiry uses deductive inference to lớn expand the implied consequences of the abductive hypothesis, with the aim of testing its truth. For this purpose, the inquirer needs to lớn think of other things that would follow from the consequence of his precipitate explanation. Thus, he now reflects on the Case just assumed:

  • Case: C → B, The Current situation is just Before it rains.

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He looks up to lớn scan the sky, perhaps in a random tìm kiếm for further information, but since the sky is a logical place to lớn look for details of an imminent rainstorm, symbolized in our story by the letter B, we may safely suppose that our reasoner has already detached the consequence of the abduced Case, C → B, and has begun to lớn expand on its further implications. So let us imagine that our up-looker has a more deliberate purpose in mind, and that his tìm kiếm for additional data is driven by the new-found, determinate Rule:

  • Rule: B → D, Just Before it rains, Dark clouds appear.

Contemplating the assumed Case in combination with this new Rule leads him by an immediate deduction to lớn predict an additional Fact:

  • Fact: C → D, In the Current situation Dark clouds appear.

The reconstructed picture of reasoning assembled in this second phase of inquiry is true to lớn the pattern of deductive inference.

Inductive phase[edit]

Whatever the case, our subject observes a Dark cloud, just as he would expect on the basis of the new hypothesis. The explanation of imminent rain removes the discrepancy between observations and expectations and thereby reduces the shock of surprise that made this process of inquiry necessary.

Looking more closely[edit]

Seeding hypotheses[edit]

Figure 4 gives a graphical illustration of Dewey's example of inquiry, isolating for the purposes of the present analysis the first two steps in the more extended proceedings that go to lớn trang điểm the whole inquiry.

o-----------------------------------------------------------o | | | A D | | o o | | \ * * / | | \ * * / | | \ * * / | | \ * * / | | \ * * / | | \ R u l e R u l e / | | \ * * / | | \ * * / | | \ * * / | | \ * B * / | | F a c t o F a c t | | \ * / | | \ * / | | \ * / | | \ * / | | \ C a s e / | | \ * / | | \ * / | | \ * / | | \ * / | | \ * / | | \*/ | | o | | C | | | | A = the Air is cool | | B = just Before it rains | | C = the Current situation | | D = a Dark cloud appears | | | | A is a major term | | B is a middle term | | C is a minor term | | D is a major term, associated with A | | | o-----------------------------------------------------------o Figure 4. Dewey's 'Rainy Day' Inquiry

In this analysis of the first steps of Inquiry, we have a complex or a mixed khuông of inference that can be seen as taking place in two steps:

  • The first step is an Abduction that abstracts a Case from the consideration of a Fact and a Rule.
Fact: C → A, In the Current situation the Air is cool.
Rule: B → A, Just Before it rains, the Air is cool.
Case: C → B, The Current situation is just Before it rains.
  • The final step is a Deduction that admits this Case to lớn another Rule and so sánh arrives at a novel Fact.
Case: C → B, The Current situation is just Before it rains.
Rule: B → D, Just Before it rains, a Dark cloud will appear.
Fact: C → D, In the Current situation, a Dark cloud will appear.

This is nowhere near a complete analysis of the Rainy Day inquiry, even insofar as it might be carried out within the constraints of the syllogistic framework, and it covers only the first two steps of the relevant inquiry process, but maybe it will vì thế for a start.

One other thing needs to lớn be noticed here, the formal duality between this expansion phase of inquiry and the argument from analogy. This can be seen most clearly in the propositional lattice diagrams shown in Figures 3 and 4, where analogy exhibits a rough "A" shape and the first two steps of inquiry exhibit a rough "V" shape, respectively. Since we find ourselves repeatedly referring to lớn this expansion phase of inquiry as a unit, let's give it a name that suggests its duality with analogy—"catalogy" will vì thế for the moment. This usage is apt enough if one thinks of a catalogue entry for an item as a text that lists its salient features. Notice that analogy has to lớn vì thế with the examples of a given quality, while catalogy has to lớn vì thế with the qualities of a given example. Peirce noted similar forms of duality in many of his early writings, leading to lớn the consummate treatment in his 1867 paper "On a New List of Categories" (CP 1.545-559, W 2, 49-59).

Weeding hypotheses[edit]

In order to lớn comprehend the bearing of inductive reasoning on the closing phases of inquiry there are a couple of observations that we need to lớn make:

  • First, we need to lớn recognize that smaller inquiries are typically woven into larger inquiries, whether we view the whole pattern of inquiry as carried on by a single agent or by a complex community.
  • Further, we need to lớn consider the different ways in which the particular instances of inquiry can be related to lớn ongoing inquiries at larger scales. Three modes of inductive interaction between the micro-inquiries and the macro-inquiries that are salient here can be described under the headings of the "Learning", the "Transfer", and the "Testing" of rules.

Analogy of experience[edit]

Throughout inquiry the reasoner makes use of rules that have to lớn be transported across intervals of experience, from the masses of experience where they are learned to lớn the moments of experience where they are applied. Inductive reasoning is involved in the learning and the transfer of these rules, both in accumulating a knowledge base and in carrying it through the times between acquisition and application.

  • Learning. The principal way that induction contributes to lớn an ongoing inquiry is through the learning of rules, that is, by creating each of the rules that goes into the knowledge base, or ever gets used along the way.
  • Transfer. The continuing way that induction contributes to lớn an ongoing inquiry is through the exploit of analogy, a two-step combination of induction and deduction that serves to lớn transfer rules from one context to lớn another.
  • Testing. Finally, every inquiry that makes use of a knowledge base constitutes a "field test" of its accumulated contents. If the knowledge base fails to lớn serve any live inquiry in a satisfactory manner, then there is a prima facie reason to lớn reconsider and possibly to lớn amend some of its rules.

Let's now consider how these principles of learning, transfer, and testing apply to lớn John Dewey's "Sign of Rain" example.


Rules in a knowledge base, as far as their effective nội dung goes, can be obtained by any mode of inference.

For example, a rule like:

  • Rule: B → A, Just Before it rains, the Air is cool,

is usually induced from a consideration of many past events, in a manner that can be rationally reconstructed as follows:

  • Case: C → B, In Certain events, it is just Before it rains,
  • Fact: C → A, In Certain events, the Air is cool,
  • Rule: B → A, Just Before it rains, the Air is cool.

However, the very same proposition could also be abduced as an explanation of a singular occurrence or deduced as a conclusion of a presumptive theory.


What is it that gives a distinctively inductive character to lớn the acquisition of a knowledge base? It is evidently the "analogy of experience" that underlies its useful application. Whenever we find ourselves prefacing an argument with the phrase "If past experience is any guide..." then we can be sure that this principle has come into play. We are invoking an analogy between past experience, considered as a totality, and present experience, considered as a point of application. What we mean in practice is this: "If past experience is a fair sample of possible experience, then the knowledge gained in it applies to lớn present experience". This is the mechanism that allows a knowledge base to lớn be carried across gulfs of experience that are indifferent to lớn the effective contents of its rules.

Here are the details of how this notion of transfer works out in the case of the "Sign of Rain" example:

Let K(pres) be a portion of the reasoner's knowledge base that is logically equivalent to lớn the conjunction of two rules, as follows:

  • K(pres) = (B → A) and (B → D).

K(pres) is the present knowledge base, expressed in the khuông of a logical constraint on the present universe of discourse.

It is convenient to lớn have the option of expressing all logical statements in terms of their logical models, that is, in terms of the primitive circumstances or the elements of experience over which they hold true.

  • Let E(past) be the chosen mix of experiences, or the circumstances that we have in mind when we refer to lớn "past experience".
  • Let E(poss) be the collective mix of experiences, or the projective total of possible circumstances.
  • Let E(pres) be the present experience, or the circumstances that are present to lớn the reasoner at the current moment.

If we think of the knowledge base K(pres) as referring to lớn the "regime of experience" over which it is valid, then all of these sets of models can be compared by the simple relations of mix inclusion or logical implication.

Figure 5 schematizes this way of viewing the "analogy of experience".

o-----------------------------------------------------------o | | | K(pres) | | o | | /|\ | | / | \ | | / | \ | | / | \ | | / Rule \ | | / | \ | | / | \ | | / | \ | | / E(poss) \ | | Fact / o \ Fact | | / * * \ | | / * * \ | | / * * \ | | / * * \ | | / * * \ | | / * Case Case * \ | | / * * \ | | / * * \ | | /* *\ | | o<<<---------------<<<---------------<<<o | | E(past) Analogy Morphism E(pres) | | More Known Less Known | | | o-----------------------------------------------------------o Figure 5. Analogy of Experience

In these terms, the "analogy of experience" proceeds by inducing a Rule about the validity of a current knowledge base and then deducing a Fact, its applicability to lớn a current experience, as in the following sequence:

Inductive Phase:

  • Given Case: E(past) → E(poss), Chosen events fairly sample Collective events.
  • Given Fact: E(past) → K(pres), Chosen events tư vấn the Knowledge regime.
  • Induce Rule: E(poss) → K(pres), Collective events tư vấn the Knowledge regime.

Deductive Phase:

  • Given Case: E(pres) → E(poss), Current events fairly sample Collective events.
  • Given Rule: E(poss) → K(pres), Collective events tư vấn the Knowledge regime.
  • Deduce Fact: E(pres) → K(pres), Current events tư vấn the Knowledge regime.

If the observer looks up and does not see dark clouds, or if he runs for shelter but it does not rain, then there is fresh occasion to lớn question the utility or the validity of his knowledge base. But we must leave our foulweather friend for now and defer the logical analysis of this testing phase to lớn another occasion.

See also[edit]


  1. ^ The UK dictionaries Collins and Longman list the spelling "inquiry" first, and Oxford simply calls it another spelling, without labeling it as US English.[1]



  • Angluin, Dana (1989), "Learning with Hints", pp. 167–181 in David Haussler and Leonard Pitt (eds.), Proceedings of the 1988 Workshop on Computational Learning Theory, MIT, 3–5 August 1988, Morgan Kaufmann, San Mateo, CA, 1989.
  • Aristotle, "Prior Analytics", Hugh Tredennick (trans.), pp. 181–531 in Aristotle, Volume 1, Loeb Classical Library, William Heinemann, London, UK, 1938.
  • Awbrey, Jon, and Awbrey, Susan (1995), "Interpretation as Action : The Risk of Inquiry", Inquiry : Critical Thinking Across the Disciplines 15, 40–52. Eprint.
  • Delaney, C.F. (1993), Science, Knowledge, and Mind: A Study in the Philosophy of C.S. Peirce, University of Notre Dame Press, Notre Dame, IN.
  • Dewey, John (1910), How We Think, D.C. Heath, Lexington, MA, 1910. Reprinted, Prometheus Books, Buffalo, NY, 1991.
  • Dewey, John (1938), Logic: The Theory of Inquiry, Henry Holt and Company, Thủ đô New York, NY, 1938. Reprinted as pp. 1–527 in John Dewey, The Later Works, 1925–1953, Volume 12: 1938, Jo Ann Boydston (ed.), Kathleen Poulos (text. ed.), Ernest Nagel (intro.), Southern Illinois University Press, Carbondale and Edwardsville, IL, 1986.
  • Haack, Susan (1993), Evidence and Inquiry: Towards Reconstruction in Epistemology, Blackwell Publishers, Oxford, UK.
  • Hanson, Norwood Russell (1958), Patterns of Discovery, An Inquiry into the Conceptual Foundations of Science, Cambridge University Press, Cambridge, UK.
  • Hendricks, Vincent F. (2005), Thought 2 Talk: A Crash Course in Reflection and Expression, Automatic Press / VIP, Thủ đô New York, NY. ISBN 87-991013-7-8
  • Maxwell, Nicholas (2007) From Knowledge to lớn Wisdom, Pentire Press, London.
  • Maxwell, Nicholas (2017), In Praise of Natural Philosophy: A Revolution for Thought and Life, McGill-Queen's University Press, Montreal.
  • Misak, Cheryl J. (1991), Truth and the End of Inquiry, A Peircean Account of Truth, Oxford University Press, Oxford, UK.
  • Peirce, C.S., (1931–1935, 1958), Collected Papers of Charles Sanders Peirce, vols. 1–6, Charles Hartshorne and Paul Weiss (eds.), vols. 7–8, Arthur W. Burks (ed.), Harvard University Press, Cambridge, MA. Cited as CP volume.paragraph.
  • Stalnaker, Robert C. (1984), Inquiry, MIT Press, Cambridge, MA.

External links[edit]

Look up inquiry in Wiktionary, the không lấy phí dictionary.

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  • Media related to lớn Inquiry at Wikimedia Commons