7 resultados para Branch of science

em Helda - Digital Repository of University of Helsinki


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This doctoral thesis in theoretical philosophy is a systematic analysis of Karl Popper's philosophy of science and its relation to his theory of three worlds. The general aim is to study Popper's philosophy of science and to show that Popper's theory of three worlds was a restatement of his earlier positions. As a result, a new reading of Popper's philosophy and development is offered and the theory of three worlds is analysed in a new manner. It is suggested that the theory of three worlds is not purely an ontological theory, but has a profound epistemological motivation. In Part One, Popper's epistemology and philosophy of science is analysed. It is claimed that Popper's thinking was bifurcated: he held two profound positions without noticing the tension between them. Popper adopted the position called the theorist around 1930 and focused on the logical structure of scientific theories. In Logik der Forschung (1935), he attempted to build a logic of science on the grounds that scientific theories may be regarded as universal statements which are not verifiable but can be falsified. Later, Popper emphasized another position, called here the processionalist. Popper focused on the study of science as a process and held that a) philosophy of science should study the growth of knowledge and that b) all cognitive processes are constitutive. Moreover, the constitutive idea that we see the world in the searchlight of our theories was combined with the biological insight that knowledge grows by trial and error. In Part Two, the theory of three worlds is analysed systematically. The theory is discussed as a cluster of theories which originate from Popper's attempt to solve some internal problems in his thinking. Popper adhered to realism and wished to reconcile the theorist and the processionalist. He also stressed the real and active nature of the human mind, and the possibility of objective knowledge. Finally, he wished to create a scientific world view.

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Structural biology is a branch of science that concentrates on the relationship between the structure and function of biological macromolecules. The prevalence of a large number of three dimensional structures offers effective tools for bio-scientists to understand the living world. Actin is the most abundant cellular protein and one of its main functions is to produce movement in living cells. Actin forms filaments that are dynamic and which are regulated by a number of different proteins. A class of these regulatory proteins contains actin depolymerizing factor homology (ADF-H) domains. These directly interact with actin through their ADF-H domains. Although ADF-H domains possess very similar three dimensional structures to one another, they vary in their functional properties. One example of this is the ability to bind to actin monomers or filaments. During the work for this thesis two structures of ADF-H domains were solved by nuclear magnetic resonance spectroscopy (NMR). The elucidated structures help us understand the binding specificities of the ADF-H family members.

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Kirjallisuuden- ja kulttuurintutkimus on viimeisten kolmen vuosikymmenen aikana tullut yhä enenevässä määrin tietoiseksi tieteen ja taiteen suhteen monimutkaisesta luonteesta. Nykyään näiden kahden kulttuurin tutkimus muodostaa oman kenttänsä, jolla niiden suhdetta tarkastellaan ennen kaikkea dynaamisena vuorovaikutuksena, joka heijastaa kulttuurimme kieltä, arvoja ja ideologisia sisältöjä. Toisin kuin aiemmat näkemykset, jotka pitävät tiedettä ja taidetta toisilleen enemmän tai vähemmän vastakkaisina pyrkimyksinä, nykytutkimus lähtee oletuksesta, jonka mukaan ne ovat kulttuurillisesti rakentuneita diskursseja, jotka kohtaavat usein samankaltaisia todellisuuden mallintamiseen liittyviä ongelmia, vaikka niiden käyttämät metodit eroavatkin toisistaan. Väitöskirjani keskittyy yllä mainitun suhteen osa-alueista popularisoidun tietokirjallisuuden (muun muassa Paul Davies, James Gleick ja Richard Dawkins) käyttämän kielen ja luonnontieteistä ideoita ammentavan kaunokirjallisuuden (muun muassa Jeanette Winterson, Tom Stoppard ja Richard Powers) hyödyntämien keinojen tarkasteluun nojautuen yli 30 teoksen kattavaa aineistoa koskevaan tyylin ja teemojen tekstianalyysiin. Populaarin tietokirjallisuuden osalta tarkoituksenani on osoittaa, että sen käyttämä kieli rakentuu huomattavassa määrin sellaisille rakenteille, jotka tarjoavat mahdollisuuden esittää todellisuutta koskevia argumentteja mahdollisimman vakuuttavalla tavalla. Tässä tehtävässä monilla klassisen retoriikan määrittelemillä kuvioilla on tärkeä rooli, koska ne auttavat liittämään sanotun sisällön ja muodon tiukasti toisiinsa: retoristen kuvioiden käyttö ei näin ollen edusta pelkkää tyylikeinoa, vaan se myös usein kiteyttää argumenttien taustalla olevat tieteenfilosofiset olettamukset ja auttaa vakiinnuttamaan argumentoinnin logiikan. Koska monet aikaisemmin ilmestyneistä tutkimuksista ovat keskittyneet pelkästään metaforan rooliin tieteellisissä argumenteissa, tämä väitöskirja pyrkii laajentamaan tutkimuskenttää analysoimalla myös toisenlaisten kuvioiden käyttöä. Osoitan myös, että retoristen kuvioiden käyttö muodostaa yhtymäkohdan tieteellisiä ideoita hyödyntävään kaunokirjallisuuteen. Siinä missä popularisoitu tiede käyttää retoriikkaa vahvistaakseen sekä argumentatiivisia että kaunokirjallisia ominaisuuksiaan, kuvaa tällainen sanataide tiedettä tavoilla, jotka usein heijastelevat tietokirjallisuuden kielellisiä rakenteita. Toisaalta on myös mahdollista nähdä, miten kaunokirjallisuuden keinot heijastuvat popularisoidun tieteen kerrontatapoihin ja kieleen todistaen kahden kulttuurin dynaamisesta vuorovaikutuksesta. Nykyaikaisen populaaritieteen retoristen elementtien ja kaunokirjallisuuden keinojen vertailu näyttää lisäksi, kuinka tiede ja taide osallistuvat keskusteluun kulttuurimme tiettyjen peruskäsitteiden kuten identiteetin, tiedon ja ajan merkityksestä. Tällä tavoin on mahdollista nähdä, että molemmat ovat perustavanlaatuisia osia merkityksenantoprosessissa, jonka kautta niin tieteelliset ideat kuin ihmiselämän suuret kysymyksetkin saavat kulttuurillisesti rakentuneen merkityksensä.

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There exists various suggestions for building a functional and a fault-tolerant large-scale quantum computer. Topological quantum computation is a more exotic suggestion, which makes use of the properties of quasiparticles manifest only in certain two-dimensional systems. These so called anyons exhibit topological degrees of freedom, which, in principle, can be used to execute quantum computation with intrinsic fault-tolerance. This feature is the main incentive to study topological quantum computation. The objective of this thesis is to provide an accessible introduction to the theory. In this thesis one has considered the theory of anyons arising in two-dimensional quantum mechanical systems, which are described by gauge theories based on so called quantum double symmetries. The quasiparticles are shown to exhibit interactions and carry quantum numbers, which are both of topological nature. Particularly, it is found that the addition of the quantum numbers is not unique, but that the fusion of the quasiparticles is described by a non-trivial fusion algebra. It is discussed how this property can be used to encode quantum information in a manner which is intrinsically protected from decoherence and how one could, in principle, perform quantum computation by braiding the quasiparticles. As an example of the presented general discussion, the particle spectrum and the fusion algebra of an anyon model based on the gauge group S_3 are explicitly derived. The fusion algebra is found to branch into multiple proper subalgebras and the simplest one of them is chosen as a model for an illustrative demonstration. The different steps of a topological quantum computation are outlined and the computational power of the model is assessed. It turns out that the chosen model is not universal for quantum computation. However, because the objective was a demonstration of the theory with explicit calculations, none of the other more complicated fusion subalgebras were considered. Studying their applicability for quantum computation could be a topic of further research.

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This study examines philosophically the main theories and methodological assumptions of the field known as the cognitive science of religion (CSR). The study makes a philosophically informed reconstruction of the methodological principles of the CSR, indicates problems with them, and examines possible solutions to these problems. The study focuses on several different CSR writers, namely, Scott Atran, Justin Barrett, Pascal Boyer and Dan Sperber. CSR theorising is done in the intersection between cognitive sciences, anthropology and evolutionary psychology. This multidisciplinary nature makes CSR a fertile ground for philosophical considerations coming from philosophy of psychology, philosophy of mind and philosophy of science. The study begins by spelling out the methodological assumptions and auxiliary theories of CSR writers by situating these theories and assumptions in the nexus of existing approaches to religion. The distinctive feature of CSR is its emphasis on information processing: CSR writers claim that contemporary cognitive sciences can inform anthropological theorising about the human mind and offer tools for producing causal explanations. Further, they claim to explain the prevalence and persistence of religion by cognitive systems that undergird religious thinking. I also examine the core theoretical contributions of the field focusing mainly on the (1) “minimally counter-intuitiveness hypothesis” and (2) the different ways in which supernatural agent representations activate our cognitive systems. Generally speaking, CSR writers argue for the naturalness of religion: religious ideas and practices are widespread and pervasive because human cognition operates in such a way that religious ideas are easy to acquire and transmit. The study raises two philosophical problems, namely, the “problem of scope” and the “problem of religious relevance”. The problem of scope is created by the insistence of several critics of the CSR that CSR explanations are mostly irrelevant for explaining religion. Most CSR writers themselves hold that cognitive explanations can answer most of our questions about religion. I argue that the problem of scope is created by differences in explanation-begging questions: the former group is interested in explaining different things than the latter group. I propose that we should not stick too rigidly to one set of methodological assumptions, but rather acknowledge that different assumptions might help us to answer different questions about religion. Instead of adhering to some robust metaphysics as some strongly naturalistic writers argue, we should adopt a pragmatic and explanatory pluralist approach which would allow different kinds of methodological presuppositions in the study of religion provided that they attempt to answer different kinds of why-questions, since religion appears to be a multi-faceted phenomenon that spans over a variety of fields of special sciences. The problem of religious relevance is created by the insistence of some writers that CSR theories show religious beliefs to be false or irrational, whereas others invoke CSR theories to defend certain religious ideas. The problem is interesting because it reveals the more general philosophical assumptions of those who make such interpretations. CSR theories can (and have been) interpreted in terms of three different philosophical frameworks: strict naturalism, broad naturalism and theism. I argue that CSR theories can be interpreted inside all three frameworks without doing violence to the theories and that these frameworks give different kinds of results regarding the religious relevance of CSR theories.