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We care not just how things are but how they could have been otherwise – about possibility and necessity as well as actuality. Many philosophers regard such talk as beyond the reach of respectable science, since observation tells us how things are but (allegedly) not how they could have been otherwise. I argue that, on the contrary, such criticisms are ill-founded: possibility and necessity are studied in natural science, for example through phase spaces, abstract mathematical representations of the possible states of a physical system. The possibility is objective, not merely epistemic, though it may be more restricted than pure metaphysical possibility. The elements of a phase space are very similar to Kripke's possible worlds, despite being time slices rather than total histories. The absence of explicit modal operators in the mathematical models used by scientists does not show science to be non-modal; rather, it manifests reliance on a mathematical framework for theorizing about objective possibility similar to the mathematical framework of possible worlds model theory.
The paper distinguishes a content-oriented conception of rational belief, which concerns support relations between the proposition believed and one's evidence, from a disposition-oriented conception of rational belief, which concerns whether someone generally disposed to conform their belief to their evidence would believe the given proposition in the given circumstances. Neither type of rationality entails the other. It is argued that conflating the two ways of thinking about rational belief has had damaging effects in epistemology.
This paper explains and defends the idea that metaphysical necessity is the strongest kind of objective necessity. Plausible closure conditions on the family of objective modalities are shown to entail that the logic of metaphysical necessity is S5. Evidence is provided that some objective modalities are studied in the natural sciences. In particular, the modal assumptions implicit in physical applications of dynamical systems theory are made explicit by using such systems to define models of a modal temporal logic. Those assumptions arguably include some necessitist principles.
Open science is a new concept for the practice of experimental laboratory-based research, such as drug discovery. The authors have recently gained experience in how to run such projects and here describe some straightforward steps others may wish to take towards more openness in their own research programmes. Existing and inexpensive online tools can solve many challenges, while some psychological barriers to the free sharing of all data and ideas are more substantial.
A paleoenvironmental time-series spanning the Holocene was constructed using 29 radiocarbon ages and 149 standardized δ13Csom values from alluvial terrace profiles along the middle Delaware River valley. There is good agreement between increasing δ13Csom and Panicoideae phytolith concentrations, suggesting that variations in C4 biomass are a major contributor to changes in the soil δ13C. A measurement error deconvolution curve over time reveals two isotope stages (II–I), with nine sub-stages exhibiting variations in average δ13Csom (average %C4). Stage II, ~ 10.7–4.3 ka, shows above-average δ13Csom (increase %C4) values with evidence of an early Holocene warming and dry interval (sub-stage IIb, 9.8–8.3 ka) that coincides with rapid warming and cool-dry abrupt climate-change events. Sub-stage IId, 7.0–4.3 ka, is an above average δ13Csom (increase %C4) interval associated with the mid-Holocene warm-dry hypsithermal. The Stage II–I shift at 4.3 ka documents a transition toward below average δ13Csom (decrease %C4) values and coincides with decreasing insolation and hydroclimatic change. Sub-stages Ib and Id (above average %C4) coincide with the first documented occurrence of maize in the northeastern USA and a substantial increase in human population during the Late Woodland. These associations suggest that people influenced δ13Csom during the late Holocene.
It seems obvious that I could have failed to exist. My parents could easily never have met, in which case I should never have been conceived and born. The like applies to everyone. More generally, it seems plausible that whatever exists in space and time could have failed to exist. Events could have taken an utterly different course. Our existence, like most other aspects of our lives, appears frighteningly contingent. It is therefore surprising that there is a proof of my necessary existence, a proof that generalizes to everything whatsoever. I will explain the proof and discuss what to make of it. A first reaction is that a ‘proof of such an outrageous conclusion must contain some dreadful fallacy. Yet the proof does not collapse under scrutiny. Further reflection suggests that, suitably interpreted, it may be sound. So interpreted, the conclusion is not outrageous, although it may not be the view you first thought of.
1. The proof rests on three main claims. The first is that my nonexistence strictly implies the truth of the proposition which states my nonexistence:
(1) Necessarily, if I do not exist then the proposition that I do not exist is true.
For that things are so-and-so is just what it takes for the proposition that they are so-and-so to be true. The second main claim is that the truth of the proposition strictly implies its existence:
(2) Necessarily, if the proposition that I do not exist is true then the proposition that I do not exist exists.