Presentism and the Notion of Existence

The aim of this paper is to make presentism a dynamic view of reality by basing it on a notion of dynamic existence, that is, on a notion of existence which has a dynamic character. The paper shows that both of the notions of existence which are used in metaphysical theories of time (in presentism and eternalism) have a static character and, while such a notion is useful for eternalists, it is useless for presentists if they want to make their view able to remain in agreement with our everyday experience and self-consistent. It is demonstrated that both empirical and theoretical arguments indicate that the presentist should replace the notion of this static existence with the notion of a dynamic existence and that this maneuver allows the presentist to treat his/her existential thesis as equivalent to the thesis that time flows. Not only does this strategy allow us to express presentism in a simple, homogenous way which remains in agreement with our experience, but also permits us to solve some of the difficult problems which presentism faces, such as, for example, the objection of triviality and the question about the rate of time passage. Moreover, such an approach to presentism allows us to solve fundamental metaphysical problems concerning time such as the problem of the openness of the future and the fixity of the past, direction of causation, and relations between presentism and persistence through time by endurance.     

Enhanced preference for a flavour following reversed flavour—glucose pairing

In two experiments hungry rats showed enhanced preference for a flavour as a result of a procedure whereby the flavour followed presentation of 10% glucose—i.e. the reverse of the usual sequence. This provides the first example of excitatory conditioning resulting from reversed pairing involving an appetitive reinforcer. Experiment 1 compared a Cinnamon group, for which ingestion of glucose was followed after 3 min by cinnamon and on other days water was followed by wintergreen, with a Wintergreen group in which wintergreen followed glucose and cinnamon followed water. In a final 2-bottle test relative preference for cinnamon was greater in the Cinnamon than in the Wintergreen group. This effect was replicated in Experiment 2, which compared an Immediate group, for which, as above, drinking glucose was followed 3 min later by access to cinnamon, with a Delay group, for which there was a delay of 1 hr between glucose and subsequent access to cinnamon. Enhanced preference for cinnamon was found only in the Immediate group and appeared after only four glucose-cinnamon pairings. An important finding came from a choice test between glucose and saccharin in which the Immediate group showed a weaker preference for glucose than the Delay group. This indicated that a novel flavour may overshadow the association between the flavour of glucose and its consequences, which normally serves to enhance preference for glucose.