Newton's Experimental Proofs

Newton's claim to provide experimental proofs is often criticized. It is argued that his proofs are based on hypotheses and not inferred from the experiments alone. This criticism, however, applies a hypothetico-deductive analysis to Newton's experimental reasoning. Such an analysis is not consistent with Newton's own understanding of his proof method. The following reconstruction of Newton's proof method is intended to do justice to his understanding by applying the conception of iconic proofs to Newton's proofs by experiment. The main purpose of this analysis is to explain Newton's dictum that the experiment alone serves as the source of evidence from which his theorems are derived. After drawing a general distinction between symbolic and iconic proofs and illustrating this distinction by means of Euclidean proofs and Aristotelian syllogisms, I will apply this distinction to Newton's experimental proofs and analyze Newton's proof of the heterogeneity of sunlight by his experimentum crucis as an iconic proof. Finally, I will show that this experiment and its underlying method remain prominent in Newton's Opticks.

The Role of Instinct in David Hume's Conception of Human Reason

This article investigates the role of instinct in Hume's understanding of human reason. It is shown that while in the Treatise Hume makes the strong reductive assertion that reason is ‘nothing but’ an instinct, in the First Enquiry the corresponding statement has been modified in several ways, rendering the relation between instinct and reason more complex. Most importantly, Hume now explicitly recognises that alongside instinctive experimental reasoning, there is a uniquely human intellectual power of intuitive and demonstrative reason that is not itself an instinct. At first sight it may look as if this intellectual reason, that is capable of grasping ‘relations of ideas’, is not even grounded in instinct but is a thoroughly non-natural element in human nature. On closer analysis, however, it is shown that intellectual reason, in its apprehension of ‘abstract’ and general relations, is dependent on language – the use of ‘terms’ – and that language itself is grounded in instinctive associations of ideas. Thus, Hume's overall view is that even the intellect is an outgrowth of instinct and his conception of human nature is, therefore, shown to be fully naturalistic. Yet this naturalism can still make room for the ‘exceptionalism’ of human mathematical thought, which has no counterpart in the animal kingdom where language is lacking.

Factors leading to immersion in obsessions

The inference-based approach (IBA) is a cognitive account of the etiology and maintenance of obsessive-compulsive disorder (OCD). According to the IBA, individuals with OCD confuse an imagined possibility with an actual probability, which leads them to become immersed in their obsessions. To investigate the relationship between OCD and the cognitive factors proposed to add to immersion, we used the Choice Blindness Paradigm (CBP). This paradigm is an experimental reasoning task designed to induce confabulatory reasoning. Undergraduate participants with high levels of OCD symptoms ( n = 29) were compared to those with low levels of OCD symptoms ( n = 32) with respect to their performance on the CBP. Compared to low-OCD participants, the results indicated that high-OCD participants were more certain (one aspect of immersion) when reasoning about falsely occurring events. However, the cognitive factors proposed by the IBA to underpin immersion did not mediate the relationship between OCD status and certainty regarding false events. Replication and refinement of the current study will help to determine the significance of these cognitive factors in obsessions.

Directional Intention Identification for Running Control of an Omnidirectional Walker

Walking is a vital exercise for health promotion and a fundamental ability necessary for everyday life. In previous work, we developed an OmniDirectional Walker (ODW) for walking rehabilitation and walking support. In walking support, it is necessary for the ODW to know the direction the user intends to go based on user manipulation. Actual directional intent must, however, be identified from physical manipulation because a user’s directional intent and physical manipulation are not always mutually consistent. In this paper, a novel interface is proposed to recognize a user’s directional intention according to the forearm pressures exerted to the ODW by the user with wrists and elbows. The forearm pressures are measured by 4 sensors embedded in the ODW’s armrest. The relationship between forearm pressure and directional intention was extracted as fuzzy rules and an algorithm was proposed for directional intention identification based on distance-type fuzzy reasoning method. The effectiveness of the algorithm was verified by experimental reasoning results demonstrated to be consistent with intended directions.