Mahdollisuus, välttämättömyys ja luodut ikuiset totuudet Descartesin filosofiassa

Tässä artikkelissa käsittelen Descartesin ikuisten totuuksien välttämättömyyteen liittyvää ongelmaa. Teoksessa Mietiskelyjä ensimmäisestä filosofiasta (1641–1642) Descartes nostaa esiin käsitteen ikuisista totuuksista, käyttäen esimerkkinään kolmiota. Kolmion muuttumattomaan ja ikuiseen luontoon kuuluu esimerkiksi, että sen kolme kulmaa ovat yhteenlaskettuna 180°. Se on totta kolmiosta, vaikka yhtään yksittäistä kolmiota ei olisi koskaan ollutkaan olemassa. Eräät ajattelemieni asioiden piirteet ovat siis Descartesin mukaan ajattelustani riippumattomia. Ikuisia totuuksia ovat ainakin matemaattiset ja geometriset tosiseikat sekä ristiriidan laki. Samoin Descartesin kuuluisa lause “ajattelen, siis olen” lukeutuu ikuisten totuuksien joukkoon. Descartesin ikuiset totuudet olisivatkin siis loogisesti välttämättömiä. Niillä on kyseinen olemus riippumatta ulkoisten kohteiden olemassaolosta tai siitä, ajattelenko niitä lainkaan. Kuitenkin kirjeenvaihdossaan Descartes pitää itsepintaisesti kiinni käsityksestään, että ikuiset totuudet ovat Jumalan vapaasti luomia ja Jumala olisi voinut luoda ne erilailla. Näin ollen luodut ikuiset totuudet eivät tarkkaan ottaen olisikaan välttämättömiä vaan kontingentteja. Ne voisivat olla myös toisella tavalla. Artikkelin alkuun esittelen Descartesin modaalista metafysiikkaa sekä luotujen ikuisten totuuksien kontingenttiudesta seuraavia tulkinnallisia vaikeuksia. Tämän jälkeen pureudun kolmeen erilaiseen ratkaisuyritykseen kommentaarikirjallisuudessa (Frankfurt 1977; Curley 1984 & Bennett 1994) ja osoitan, miksi ne eivät riitä vastaamaan ongelmaan. Lopussa vedän johtopäätöksiä ja luonnostelen mahdollisen ratkaisun

Dressed Counterions: Poly- and monovalent ions at charged dielectric interfaces

We investigate the ion distribution and overcharging at charged interfaces with dielectric inhomogeneities in the presence of asymmetric electrolytes containing polyvalent and monovalent ions. We formulate an effective "dressed counterion" approach by integrating out the monovalent salt degrees of freedom and show that it agrees with results of explicit Monte-Carlo simulations. We then apply the dressed counterion approach within the framework of the strong-coupling theory, valid for polyvalent ions at low concentrations, which enables an analytical description for salt effects as well as dielectric inhomogeneities in the limit of strong Coulomb interactions on a systematic level. Limitations and applicability of this theory are examined by comparing the results with simulations.Comment: 9 pages, 5 figure

A Many-Body Hamiltonian for Nanoparticles Immersed in a Polymer Solution

We developed an analytical theory for the many-body potential of mean force (POMF) between N spheres immersed in a continuum chain fluid. The theory is almost exact for a T polymer solution in the protein limit (small particles, long polymers), where N-body effects are important. Polydispersity in polymer length according to a SchulzFlory distribution emerges naturally from our analysis, as does the transition to the monodisperse limit. The analytical expression for the POMF allows for computer simulations employing the complete N-body potential (i.e., without n-body truncation; n < N). These are compared with simulations of an explicit particle/polymer mixture. We show that the theory produces fluid structure in excellent agreement with the explicit model simulations even when the system is strongly fluctuating, e.g., at or near the spinodal region. We also demonstrate that other commonly used theoretical approaches, such as truncation of the POMF at the pair level or the Asakura Oosawa model, are extremely inaccurate for these systems

Attraction between Neutral Dielectrics Mediated by Multivalent Ions in an Asymmetric Ionic Fluid

We study the interaction between two neutral plane-parallel dielectric bodies in the presence of a highly asymmetric ionic fluid, containing multivalent as well as monovalent (salt) ions. Image charge interactions, due to dielectric discontinuities at the boundaries, as well as effects from ion confinement in the slit region between the surfaces are taken fully into account, leading to image-generated depletion attraction, ion correlation attraction and steric-like repulsive interactions. We investigate these effects by employing a combination of methods including explicit-ion and implicit-ion Monte-Carlo simulations, as well as an effective interaction potential analytical theory. The latter incorporates strong ion-image charge correlations, which develop in the presence of high valency ions in the mixture. We show that the implicit-ion simulations and the proposed analytical theory can describe the explicit simulation results on a qualitative level, while excellent quantitative agreement can be obtained for sufficiently large monovalent salt concentrations. The resultant attractive interaction between the neutral surfaces is shown to be significant, as compared with the usual van der Waals interactions between semi-infinite dielectrics, and can thus play a significant role at the nano scale.Comment: 9 pages, 4 figure

Epäilijöitä ja tiedon etsijöitä

Kirja-arvio: Malin Grahn-Wilder (toim.): Skeptisismi: Epäilyn ja etsimisen filosofia. Gaudeamus, Helsinki 2016. 453 sivua. &nbsp;Mitä on tieto ja kellä sitä on? Voimmeko tietää miten asiat todella ovat? Voimmeko ylipäätään tietää mitään? Malin Grahn-Wilderin toimittama teos Skeptisismi on kattava läpileikkaus skeptisismin historiasta antiikin juuriltaan aina nykyajan keskusteluihin saakka. Samalla se sisältää ensimmäistä kertaa suomeksi käännettynä useammankin (skeptisistisen) filosofian historialle ehdottoman olennaisen kirjoituksen

Of Dreams, Demons, and Whirlpools: Doubt, Skepticism, and Suspension of Judgment in Descartes's Meditations

I offer a novel reading in this dissertation of René Descartes’s (1596–1650) skepticism in his work Meditations on First Philosophy (1641–1642). I specifically aim to answer the following problem: How is Descartes’s skepticism to be read in accordance with the rest of his philosophy? This problem can be divided into two more general questions in Descartes scholarship: How is skepticism utilized in the Meditations, and what are its intentions and relation to the preceding philosophical tradition? I approach the topic from both a historical and a text-based analysis, combining textual and contextual research. I examine Descartes’s skepticism against two main traditions in the historical analysis: philosophical skepticism and Aristotelian Scholasticism. I argue that skepticism in the Meditations is intended to oppose and upheave both Scholasticism and skepticism. The intended results of the work are not merely epistemological but also metaphysical and even ethical. Furthermore, these ambitions cannot be neatly distinguished but merge into each other. The third historical context against which the skeptical meditations are examined is the literary genre of meditative exercises, particularly from the 1500–1600’s, which, while religiously and spiritually oriented, likewise provided the practitioner with an enlightened understanding of self-knowledge and their cognitive place in the world on the way to closer spiritual proximity to God. I argue by this reading that the skepticism of the Meditations is an attentive, meditational cognitive exercise that is not merely instrumental and methodological but is to have a genuine and serious (psychologically real) effect on our thinking. The skeptical meditation is not simply a theoretical thought experiment but is to be seriously practiced as a transformative process of reorienting one’s cognitive framework to discover truth, certainty, and a way to a happy, tranquil, and virtuous life. I offer a close reading in the textual analysis of the first three meditations of the Meditations. I argue that the meditative skepticism employed in the work does not reject the previous beliefs but suspends judgment on them, withdrawing assent until further evidence can be found. I introduce a new term into Descartes scholarship in this analysis, based on the terminology of ancient skepticism: Cartesian epochē (gr. epochē, suspension, withdrawal). Instead of rejecting previous beliefs or assenting to the probably false, the skeptical procedure of the Meditations is argued to emulate in important ways the suspension of judgment on equally balanced reasons in ancient Pyrrhonian skepticism. Novel interpretations are presented along the way of the will’s freedom, of the First Meditation’s skeptical scenarios, of the cogito, and of the vindication of metaphysical certainty, as well as a clarification of the Cartesian Circle problem. Reinterpreting the relation of Descartes’s skepticism to the preceding historical and literary traditions leads to a new look at the skeptical method itself. Presenting a new interpretation of skepticism in the Meditations leads at the same time to a new look at its relation to the historical context. The two research questions are, then, intrinsically tied together. My focus in the study is on the Meditations, but I also reference and discuss Descartes’s other philosophical works, as well as his correspondence, when necessary

Miesvallan murtajat

Reuter, Martina (toim.): Miesvaltaa murtamassa: Varhaisten feministien filosofisia kirjoituksia. Gaudeamus 2021

Epäily, skeptisismi ja arvostelmasta pidättäytyminen Descartesin Mietiskelyissä

Epäily, skeptisismi ja arvostelmasta pidättäytyminen Descartesin Mietiskelyissä

Fluid-Fluid Transitions at Bulk Supercritical Conditions

We use three different polymer solvent mixture models to theoretically determine the existence of capillary-induced phase separation in simple pores under supercritical bulk conditions. These models undergo bulk demixing, due to quite different mechanisms, yet readily display supercritical transitions without the use of esoteric interactions in the capillary. The theoretical method used to analyze these systems is density functional theory. We find that capillary demixing is not reliant on the presence of a pure surface transition but may occur in the absence of the latter. This is shown by considering cases where the surface enhancement factor is too weak to cause demixing at a single surface or else the bulk conditions are supercritical to both bulk and surface transitions. This phenomenon may prove useful in applications involving adsorption from mixtures into porous particles