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Structuralism (philosophy of mathematics)
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<h2 id="historical-motivation">Historical motivation</h2> <p>The historical motivation for the development of structuralism derives from a fundamental problem of <a href="/facts/Ontology/QJKTsEIJ">ontology</a>. Since <a href="/facts/Medieval_philosophy/f1PmX7FB">Medieval</a> times, philosophers have argued as to whether the ontology of mathematics contains <a href="/facts/Abstract_object/uNshak6S">abstract objects</a>. In the philosophy of mathematics, an abstract object is traditionally defined as an entity that: </p><p>(1) exists independent of the mind; </p><p>(2) exists independent of the empirical world; and </p><p>(3) has eternal, unchangeable properties. </p><p>Traditional mathematical <a href="/facts/Platonism/0mvr2x2p">Platonism</a> maintains that some set of mathematical elements—<a href="/facts/Natural_number/u65og8JE">natural numbers</a>, <a href="/facts/Real_number/R02gw5Pb">real numbers</a>, <a href="/facts/Function_(mathematics)/CdReEKCh">functions</a>, <a href="/facts/Relation_(mathematics)/HjblDaMy">relations</a>, <a href="/facts/System/hmqQ4ASX">systems</a>—are such abstract objects. Contrarily, mathematical <a href="/facts/Nominalism/3FE99hPX">nominalism</a> denies the existence of any such abstract objects in the ontology of mathematics. </p><p>In the late 19th and early 20th century, a number of anti-Platonist programs gained in popularity. These included <a href="/facts/Intuitionism/1gTeosv9">intuitionism</a>, <a href="/facts/Formalism_(mathematics)/g0690AVL">formalism</a>, and <a href="/facts/Predicativism/gDuxRrb5">predicativism</a>. By the mid-20th century, however, these anti-Platonist theories had a number of their own issues. This subsequently resulted in a resurgence of interest in Platonism. It was in this historic context that the motivations for structuralism developed. In 1965, <a href="/facts/Paul_Benacerraf/o4vJm1fR">Paul Benacerraf</a> published an article entitled "What Numbers Could Not Be".<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Benacerraf concluded, on two principal arguments, that <a href="/facts/Set_theory/1ptfsvUP">set-theoretic</a> Platonism cannot succeed as a philosophical theory of mathematics. </p><p>Firstly, Benacerraf argued that Platonic approaches do not pass the ontological test.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> He developed an argument against the ontology of set-theoretic Platonism, which is now historically referred to as <a href="/facts/Benacerraf%2527s_identification_problem/w1m4WeUn">Benacerraf's identification problem</a>. Benacerraf noted that there are <a href="/facts/Elementarily_equivalent/3C94AfFq">elementarily equivalent</a>, set-theoretic ways of relating natural numbers to <a href="/facts/Pure_sets/edFwmXa8">pure sets</a>. However, if someone asks for the "true" identity statements for relating natural numbers to pure sets, then different set-theoretic methods yield contradictory identity statements when these elementarily equivalent sets are related together.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> This generates a set-theoretic falsehood. Consequently, Benacerraf inferred that this set-theoretic falsehood demonstrates it is impossible for there to be any Platonic method of reducing numbers to sets that reveals any abstract objects. </p><p>Secondly, Benacerraf argued that Platonic approaches do not pass the <a href="/facts/Epistemological/NsDwpcYH">epistemological</a> test. Benacerraf contended that there does not exist an empirical or rational method for accessing abstract objects. If mathematical objects are not spatial or temporal, then Benacerraf infers that such objects are not accessible through the <a href="/facts/Causal_theory_of_knowledge/PLnaSpf1">causal theory of knowledge</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The fundamental epistemological problem thus arises for the Platonist to offer a plausible account of how a mathematician with a limited, empirical mind is capable of accurately accessing mind-independent, world-independent, eternal truths. It was from these considerations, the ontological argument and the epistemological argument, that Benacerraf's anti-Platonic critiques motivated the development of structuralism in the philosophy of mathematics. </p> <h2 id="varieties">Varieties</h2> <p><a href="/facts/Stewart_Shapiro/Rk9rxnkK">Stewart Shapiro</a> divides structuralism into three major schools of thought.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> These schools are referred to as the <i>ante rem</i>, the <i>in re</i>, and the <i>post rem</i>. </p> <ul><li>The <i>ante rem</i> structuralism<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> ("before the thing"), or abstract structuralism<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> or abstractionism<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> (particularly associated with <a href="/facts/Michael_Resnik/hrI6nB1W">Michael Resnik</a>,<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> <a href="/facts/Stewart_Shapiro/Rk9rxnkK">Stewart Shapiro</a>,<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> <a href="/facts/Edward_N._Zalta/U8JxHaaA">Edward N. Zalta</a>,<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> and <a href="/facts/%25C3%2598ystein_Linnebo/uveGBfkv">Øystein Linnebo</a>)<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> has a similar ontology to <a href="/facts/Mathematical_Platonism/z7xBcdWA">Platonism</a> (see also <a href="/facts/Modal_neo-logicism/YvHs6X3E">modal neo-logicism</a>). Structures are held to have a real but abstract and immaterial existence. As such, it faces the standard epistemological problem, as noted by Benacerraf, of explaining the interaction between such abstract structures and flesh-and-blood mathematicians.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></li> <li>The <i>in rem</i> structuralism<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> ("in the thing"),<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> or modal structuralism<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> (particularly associated with <a href="/facts/Geoffrey_Hellman/7mfgbn50">Geoffrey Hellman</a>),<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> is the equivalent of <a href="/facts/Aristotelian_realist_philosophy_of_mathematics/3au3NJsl">Aristotelian realism</a><a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> (realism in truth value, but <a href="/facts/Anti-realism/cAezj0SC">anti-realism</a> about <a href="/facts/Abstract_object/uNshak6S">abstract objects</a> in ontology). Structures are held to exist inasmuch as some concrete system exemplifies them. This incurs the usual issues that some perfectly legitimate structures might accidentally happen not to exist, and that a finite physical world might not be "big" enough to accommodate some otherwise legitimate structures. The Aristotelian realism of James Franklin is also an <i>in re</i> structuralism, arguing that structural properties such as symmetry are instantiated in the physical world and are perceivable.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> In reply to the problem of uninstantiated structures that are too big to fit into the physical world, Franklin replies that other sciences can also deal with uninstantiated universals; for example the science of color can deal with a shade of blue that happens not to occur on any real object.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a></li> <li>The <i>post rem</i> structuralism<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> ("after the thing"), or eliminative structuralism<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> (particularly associated with <a href="/facts/Paul_Benacerraf/o4vJm1fR">Paul Benacerraf</a>),<a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> is <a href="/facts/Anti-realism/cAezj0SC">anti-realist</a> about structures in a way that parallels <a href="/facts/Nominalism/3FE99hPX">nominalism</a>. Like nominalism, the <i>post rem</i> approach denies the existence of abstract mathematical objects with properties other than their place in a relational structure. According to this view mathematical <i>systems</i> exist, and have structural features in common. If something is true of a structure, it will be true of all systems exemplifying the structure. However, it is merely instrumental to talk of structures being "held in common" between systems: they in fact have no independent existence.</li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Abstract_object_theory/ev5u3gxo">Abstract object theory</a></li> <li><a href="/facts/Foundations_of_mathematics/yjpbbUkt">Foundations of mathematics</a></li> <li><a href="/facts/Univalent_foundations/jFNzb0my">Univalent foundations</a></li> <li><a href="/facts/Aristotelian_realist_philosophy_of_mathematics/3au3NJsl">Aristotelian realist philosophy of mathematics</a></li></ul> <p>Precursors </p> <ul><li><a href="/facts/Nicolas_Bourbaki/qRJhs9nr">Nicolas Bourbaki</a></li></ul> <h2 id="bibliography">Bibliography</h2> <ul><li>Franklin, James (2014). <a href="https://books.google.com/books?id=0YKEAwAAQBAJ"><i>An Aristotelian Realist Philosophy of Mathematics: Mathematics as the Science of Quantity and Structure</i></a>. Palgrave Macmillan. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-1-137-40072-7.</li> <li>Resnik, Michael (1982). "Mathematics as a Science of Patterns: Epistemology". <i>Noûs</i>. 16 (1): 95–105. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.2307%2F2215419">10.2307/2215419</a>. <a href="/facts/JSTOR_(identifier)/YTeVmaJ7">JSTOR</a> <a href="https://www.jstor.org/stable/2215419">2215419</a>.</li> <li>Resnik, Michael (1997). <a href="https://books.google.com/books?id=EU2G_BFt7YsC"><i>Mathematics as a Science of Patterns</i></a>. Clarendon Press. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-19-825014-2.</li> <li>Shapiro, Stewart (1997). <a href="https://oxford.universitypressscholarship.com/view/10.1093/0195139305.001.0001/acprof-9780195139303"><i>Philosophy of Mathematics: Structure and Ontology</i></a>. Oxford University Press. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1093%2F0195139305.001.0001">10.1093/0195139305.001.0001</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-19-513930-3.</li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="http://www.iep.utm.edu/m-struct/"><i>Mathematical Structuralism</i>, Internet Encyclopaedia of Philosophy</a></li> <li><a href="http://www.iep.utm.edu/abstract/"><i>Abstractionism</i>, Internet Encyclopaedia of Philosophy</a></li> <li><a href="http://www.bristol.ac.uk/structuralism/">Foundations of Structuralism research project</a>, University of Bristol, UK</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Brown, James (2008). Philosophy of Mathematics. Routledge. p. 62. ISBN 978-0-415-96047-2. <a href="978-0-415-96047-2" target="_blank">978-0-415-96047-2</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Benacerraf, Paul (1965). "What Numbers Could Not Be". Philosophical Review. 74 (1): 47–73. doi:10.2307/2183530. JSTOR 2183530. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Benacerraf, Paul (1965). "What Numbers Could Not Be". Philosophical Review. 74 (1): 47–73. doi:10.2307/2183530. JSTOR 2183530. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Benacerraf, Paul (1965). "What Numbers Could Not Be". Philosophical Review. 74 (1): 47–73. doi:10.2307/2183530. JSTOR 2183530. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Benacerraf, Paul (1983). "Mathematical Truth". In Putnam, H.W.; Benacerraf, P. (eds.). Philosophy of Mathematics: Selected Readings (2nd ed.). Cambridge University Press. pp. 403–420. ISBN 978-0-521-29648-9. <a href="978-0-521-29648-9" target="_blank">978-0-521-29648-9</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Shapiro 1997, p. 9 - Shapiro, Stewart (1997). Philosophy of Mathematics: Structure and Ontology. Oxford University Press. doi:10.1093/0195139305.001.0001. ISBN 978-0-19-513930-3. <a href="https://oxford.universitypressscholarship.com/view/10.1093/0195139305.001.0001/acprof-9780195139303" target="_blank">https://oxford.universitypressscholarship.com/view/10.1093/0195139305.001.0001/acprof-9780195139303</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Tennant, Neil (2017), "Logicism and Neologicism", in Zalta, Edward N. (ed.), The Stanford Encyclopedia of Philosophy (Winter 2017 ed.), Metaphysics Research Lab, Stanford University, retrieved 2022-07-10. <a href="https://plato.stanford.edu/archives/win2017/entries/logicism/" target="_blank">https://plato.stanford.edu/archives/win2017/entries/logicism/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Not to be confused with abstractionist Platonism. <a href="/wiki/Abstractionist_Platonism" target="_blank">/wiki/Abstractionist_Platonism</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Zalta, Edward N.; Nodelman, Uri (February 2011). "A Logically Coherent Ante Rem Structuralism" (PDF). Ontological Dependence Workshop. University of Bristol. <a href="http://www.bris.ac.uk/structuralism/media/zalta-slides.pdf" target="_blank">http://www.bris.ac.uk/structuralism/media/zalta-slides.pdf</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Linnebo, Øystein (2018). Thin Objects: An Abstractionist Account. Oxford University Press. ISBN 978-0-19-255896-1. <a href="978-0-19-255896-1" target="_blank">978-0-19-255896-1</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Benacerraf, Paul (1983). "Mathematical Truth". In Putnam, H.W.; Benacerraf, P. (eds.). Philosophy of Mathematics: Selected Readings (2nd ed.). Cambridge University Press. pp. 403–420. ISBN 978-0-521-29648-9. <a href="978-0-521-29648-9" target="_blank">978-0-521-29648-9</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Shapiro 1997, p. 9 - Shapiro, Stewart (1997). Philosophy of Mathematics: Structure and Ontology. Oxford University Press. doi:10.1093/0195139305.001.0001. ISBN 978-0-19-513930-3. <a href="https://oxford.universitypressscholarship.com/view/10.1093/0195139305.001.0001/acprof-9780195139303" target="_blank">https://oxford.universitypressscholarship.com/view/10.1093/0195139305.001.0001/acprof-9780195139303</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Shapiro 1997, p. 9 - Shapiro, Stewart (1997). Philosophy of Mathematics: Structure and Ontology. Oxford University Press. doi:10.1093/0195139305.001.0001. ISBN 978-0-19-513930-3. <a href="https://oxford.universitypressscholarship.com/view/10.1093/0195139305.001.0001/acprof-9780195139303" target="_blank">https://oxford.universitypressscholarship.com/view/10.1093/0195139305.001.0001/acprof-9780195139303</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>da Silva, Jairo José (2017). Mathematics and Its Applications: A Transcendental-Idealist Perspective. Springer. p. 265. ISBN 978-3-319-63073-1. <a href="978-3-319-63073-1" target="_blank">978-3-319-63073-1</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Franklin 2014, pp. 48–59 - Franklin, James (2014). An Aristotelian Realist Philosophy of Mathematics: Mathematics as the Science of Quantity and Structure. Palgrave Macmillan. ISBN 978-1-137-40072-7. <a href="https://books.google.com/books?id=0YKEAwAAQBAJ" target="_blank">https://books.google.com/books?id=0YKEAwAAQBAJ</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Franklin, James (2015). "Uninstantiated Properties and Semi-Platonist Aristotelianism". Review of Metaphysics. 69 (1): 25–45. JSTOR 24636591. Retrieved 29 June 2021. <a href="https://www.academia.edu/11344862" target="_blank">https://www.academia.edu/11344862</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Nefdt, Ryan M. (2018). "Inferentialism and Structuralism: A Tale of Two Theories". Logique et Analyse. 244: 489–512. doi:10.2143/LEA.244.0.3285352. <a href="http://philsci-archive.pitt.edu/id/eprint/14856" target="_blank">http://philsci-archive.pitt.edu/id/eprint/14856</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>Shapiro, Stewart (May 1996). "Mathematical Structuralism". Philosophia Mathematica. 4 (2): 81–82. doi:10.1093/philmat/4.2.81. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> </ol>