{{Redirect|Mental object|3=Mental model (disambiguation)}}{{short description|Object that exists in the imagination}} An '''object of the mind''' is an [[object (philosophy)|object]] that [[Existence|exists]] in the [[mind]] or [[imagination]], but which, in the real world, can only be represented or modeled. Some such objects are [[abstraction]]s, [[concept]]s and [[scenario]]s in [[literature]] and [[fiction]].
Closely related are '''intentional objects''', which are what thoughts and feelings are about ([[intentionality|intentionality]]), even if they are not about anything real (such as thoughts about [[unicorn]]s, or feelings of apprehension about a dental appointment which is subsequently cancelled).<ref>[https://www.academia.edu/28177480/Intentional_Objects Tim Crane - ''Intentional Objects''].</ref> However, intentional objects may coincide with real objects (as in thoughts about horses, or a feeling of regret about a missed appointment).
==Mathematical objects== {{Main articles|Mathematical object}} Mathematics and geometry describe [[abstract object]]s that sometimes correspond to familiar shapes, and sometimes do not. Circles, triangles, rectangles, and so forth describe two-dimensional shapes that are often found in the real world. However, mathematical formulas do not describe individual physical circles, triangles, or rectangles. They describe ideal shapes that are [[object (philosophy)|object]]s of the [[mind]]. The incredible precision of mathematical expression permits a vast applicability of mental abstractions to real life situations.
Many more mathematical formulas describe shapes that are unfamiliar, or do not necessarily correspond to objects in the real world. For example, the [[Klein bottle]]<ref>[[Edward Burger|Burger, E. B.]], & [[Michael Starbird|Starbird, M.]], "A One-Sided, Sealed Surface—The Klein Bottle", in E. B. Burger, M. Starbird, T. Stonebarger, & T. Dunton, ''Joy of Thinking: The Beauty and Power of Classical Mathematical Ideas'' ([[Chantilly, Virginia|Chantilly, VA]]: [[The Great Courses|The Teaching Company]], 2003).</ref> is a one-sided, sealed surface with no inside or outside (in other words, it is the three-dimensional equivalent of the [[Möbius strip]]).<ref>[[Ari Ben-Menahem|Ben-Menahem, A.]], ''Historical Encyclopedia of Natural and Mathematical Sciences'' ([[New York City|New York]]: [[Springer Science+Business Media|Springer]], 2009), [https://books.google.com/books?id=9tUrarQYhKMC&pg=PA2029&redir_esc=y#v=onepage&q&f=false p. 2029].</ref>{{rp|2029}} Such objects can be represented by twisting and cutting or taping pieces of paper together, as well as by computer simulations. To hold them in the imagination, abstractions such as extra or fewer dimensions are necessary.
==Logical sequences== [[Deductive reasoning#Modus ponens|If-then arguments]] posit [[logical]] [[sequences]] that sometimes include objects of the mind. For example, a [[counterfactual conditional|counterfactual]] argument proposes a [[hypothetical]] or [[subjunctive]] [[Subjunctive possibility|possibility]] which ''could'' or ''would'' be true, but ''might not'' be false. [[Conditional probability|Conditional]] sequences involving subjunctives use [[intensional logic|intensional]] language, which is studied by [[modal logic]],<ref>{{Cite web |title=Modal logic - Encyclopedia of Mathematics |url=https://encyclopediaofmath.org/wiki/Modal_logic |access-date=2022-07-11 |website=encyclopediaofmath.org}}</ref> whereas [[classical logic]] studies the [[extensional]] language of [[logical possibility|necessary]] and [[sufficient]] conditions.
In general, a logical [[antecedent (logic)|antecedent]] is a sufficient condition, and a logical [[consequent]] is a necessary condition (or the [[Contingency (philosophy)|contingency]]) in a [[logical conditional]]. But logical conditionals accounting only for necessity and sufficiency do not always reflect every day if-then reasoning, and for this reason they are sometimes known as [[material conditional]]s. In contrast, [[indicative conditional]]s, sometimes known as non-material conditionals,<ref>Payne, W. R., "The Non-material Conditional".</ref> attempt to describe if-then reasoning involving hypotheticals, fictions, or counterfactuals.
[[Truth tables]] for if-then statements identify four unique combinations of premises and conclusions: true premises and true conclusions; false premises and true conclusions; true premises and false conclusions; false premises and false conclusions. [[Strict conditional]]s assign a positive [[truth-value]] to every case except the case of a true premise and a false conclusion. This is sometimes regarded as counterintuitive, but makes more sense when false conditions are understood as objects of the mind.
===False antecedent=== A false antecedent is a premise known to be false, fictional, imaginary, or unnecessary. In a conditional sequence, a false antecedent may be the basis for any consequence, true or false.<ref>[[Richard Murray (mathematician)|Murray, R.]], with [[John James Walker|Walker, J. J.]], & Wheeler, G. B., ''Murray's Compendium of Logic—with an Accurate Translation, and a Familiar Commentary'' (Dublin: M. W. Rooney, 1852; London: [[Simpkin & Marshall]], 1852), [https://books.google.com/books?id=cndZAAAAcAAJ&pg=PA150&redir_esc=y#v=onepage&q&f=false pp. 150–151].</ref>{{rp|150–151}}
The subjects of [[literature]] are sometimes false antecedents. Examples include the contents of false documents, the origins of [[wikt:stand-alone|stand-alone]] phenomena, or the implications of [[loaded words]]. Moreover, artificial sources, personalities, events, and histories. False antecedents are sometimes referred to as "[[nothing]]", or "[[nonexistent]]", whereas nonexistent referents are not referred to.<ref>[[Raymond S. Nickerson|Nickerson, R. S.]], ''Conditional Reasoning: The Unruly Syntactics, Semantics, Thematics, and Pragmatics of "If"'' (Oxford & New York: [[Oxford University Press]], 2015), [https://books.google.com/books?id=ZrsDCgAAQBAJ&pg=PA5&redir_esc=y#v=onepage&q&f=false pp. 5–258].</ref>{{rp|5–258}}
[[Art]] and [[acting]] often portray scenarios without any antecedent other than an artist's imagination. For example, mythical heroes, legendary creatures, gods and goddesses.
===False consequent=== A false consequent, in contrast, is a conclusion known to be false, fictional, imaginary, or insufficient. In a conditional statement, a fictional conclusion is known as a [[non sequitur (logic)|non sequitur]], which literally means ''out of sequence''. A conclusion that is out of sequence is not contingent on any premises that precede it, and it does not follow from them, so such a sequence is not conditional. A conditional sequence is a connected series of statements. A false consequent cannot follow from true premises in a connected sequence. But, on the other hand, a false consequent can follow from a false antecedent.<ref>[[A. A. Long|Long, A. A.]], & [[David Sedley|D. N. Sedley]], ''The Hellenistic Philosophers: Translations of the principal sources, with philosophical commentary'' (Cambridge: [[Cambridge University Press]], 1987), [https://books.google.com/books?id=AfemGeG8SysC&lpg=PA209&hl=cs&pg=PA209&redir_esc=y#v=onepage&q&f=false p. 209].</ref>{{rp|209}}
As an example, the name of a [[team]], a [[genre]], or a [[nation]] is a collective term applied [[ex post facto]] to a group of distinct individuals. None of the individuals on a sports team is the team itself, nor is any musical chord a genre, nor any person America. The name is an identity for a collection that is connected by consensus or [[reference]], but not by sequence. A different name could equally follow, but it would have different [[social]] or [[political]] [[meaning (semiotics)|significance]].
==Philosophy== {{main|Nonexistent objects}} {{also|Empty name|Noneism|Theory of descriptions|Nonexistence|Meontology}} In [[metaphysics]] and [[ontology]], Austrian philosopher [[Alexius Meinong]] advanced [[nonexistent objects]] in the 19th and 20th century within a "[[Abstract object theory|theory of objects]]". He was interested in intentional states which are directed at nonexistent objects. Starting with the "principle of [[intentionality]]", mental phenomena are intentionally directed towards an object. People may imagine, desire or fear something that does not exist. Other philosophers concluded that intentionality is not a real relation and therefore does not require the existence of an object, while Meinong concluded there is an object for every mental state whatsoever—if not an existent then at least a nonexistent one.<ref>''[[Stanford Encyclopedia of Philosophy]]'', [https://plato.stanford.edu/entries/nonexistent-objects/#HistRootAlexMeinProbInte "Nonexistent Objects: Historical Roots"].</ref>
===Philosophy of mind=== {{main|Mind–body dualism}} In [[philosophy of mind]], [[mind–body dualism]] is the doctrine that mental activities exist apart from the physical body, notably posited by [[René Descartes]] in ''[[Meditations on First Philosophy]]''.
==Invented sources== {{main|False document}} {{further|Tolkien's frame stories}}
Many objects in fiction follow the example of false antecedents or false consequents. For example, ''[[The Lord of the Rings]]'' by [[J.R.R. Tolkien]] is based on an imaginary book. In the ''Appendices'' to ''The Lord of the Rings'', Tolkien's characters name the ''[[Red Book of Westmarch]]'' as the source material for ''The Lord of the Rings'', which they describe as a translation. But the ''Red Book of Westmarch'' is a fictional document that chronicles events in an [[imaginary world]].
==Convenient fictions== {{see|Fictionalism}} [[Social reality]] is composed of many standards and [[inventions]] that facilitate [[communication]], but which are ultimately objects of the mind. For example, [[money]] is an object of the mind which [[currency]] represents. Similarly, [[language]]s signify [[idea]]s and [[thoughts]].
Objects of the mind are frequently involved in the roles that people play. For example, [[acting]] is a profession which predicates real jobs on fictional premises. [[Charades]] is a game people play by guessing imaginary objects from short play-acts.
Imaginary [[personalities]] and histories are sometimes invented to enhance the [[verisimilitude]] of [[fictional universes]], and/or the [[immersion (virtual reality)|immersion]] of [[role-playing games]]. In the sense that they exist independently of extant personalities and histories, they are believed to be fictional characters and fictional time frames.
[[Science fiction]] is abundant with future times, alternate times, and past times that are objects of the mind. For example, in the novel ''[[Nineteen Eighty-Four]]'' by [[George Orwell]], the number 1984 represented a year that had not yet passed.
[[Calendar date]]s also represent objects of the mind, specifically, past and future times. In ''[[The Transformers: The Movie]]'', which was released in 1986, the narration opens with the statement, "It is the year 2005." In 1986, that statement was futuristic. During the year 2005, that reference to the year 2005 was factual. Now, ''The Transformers: The Movie'' is [[retro-futuristic]]. The number 2005 did not change, but the object of the mind that it represents did change.
Deliberate [[invention]] also may reference an object of the mind. The intentional invention of fiction for the purpose of [[deception]] is usually referred to as [[lie|lying]], in contrast to invention for [[entertainment]] or [[art]]. Invention is also often applied to [[problem solving]]. In this sense the physical invention of materials is associated with the [[mind|mental]] invention of fictions.
Convenient fictions also occur in science.
==Science== The theoretical posits of one era's scientific theories may be demoted to mere objects of the mind by subsequent discoveries: some standard examples include [[phlogiston]] and [[ptolemaic epicycle]]s.
This raises questions, in the debate between [[scientific realism]] and [[instrumentalism]] about the status of current posits, such as [[black hole]]s and [[quark]]s.
The situation is further complicated by the existence in scientific practice of entities which are explicitly held not to be real, but which nonetheless serve a purpose—convenient fictions. Examples include [[field line|field lines]], [[centers of gravity]], and [[electron hole]]s in semiconductor theory.
==Self-reference== {{Original research|section|date=September 2007}} A [[reference]] that names an imaginary [[source text|source]] is in some sense also a [[self-reference]]. A self-reference automatically makes a comment about itself. Premises that name themselves as premises are premises by self-reference; conclusions that name themselves as conclusions are conclusions by self-reference.
In their respective [[imaginary world]]s the ''[[Necronomicon]]'', ''[[The Hitchhiker's Guide to the Galaxy]]'', and the ''[[Red Book of Westmarch]]'' are realities, but only because they are referred to as real. Authors use this technique to invite readers to [[roleplaying|pretend]] or to make-believe that their imaginary world is real. In the sense that the stories that quote these books are true, the quoted books exist; in the sense that the stories are fiction, the quoted books do not exist.
==See also== * [[Abstraction]] * [[Existence]] * [[Intentionality]] * [[Noumenon]] * ''[[The Concept of Mind]]'' * [[Unobservable]] * [[Impossible world]] * [[Incompleteness theorems]]
==References== {{reflist|35em}}
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