onhierarchical physics in order to counter Jaegwon Kim's objections to the notion of downward causation needed for strong emergence. The thesis presents arguments against Thompson's holism and nonfundamental physics, while supporting his assertion regarding the incipient stages of cognition. It then combines an important distinction between mental causation and the experience of mental causation with Thompson's notion of incipient cognition to arrive at a dual realms approach to understanding mental causation.
In 1965, Austin Bradford Hill published the article “The Environment and Disease: Association or Causation?” in the Proceedings of the Royal Society of Medicine. In the article, Hill describes nine criteria to determine if an environmental factor, especially a condition or hazard in a work environment, causes an illness. The article arose from an inaugural presidential address Hill gave at the 1965 meeting of the Section of Occupational Medicine of the Royal Society of Medicine in London, England. The criteria he established in the article became known as the Bradford Hill criteria and the medical community refers to them when determining whether an environmental condition causes an illness. The criteria outlined in “The Environment and Disease: Association or Causation?” help identify the causes of many diseases, including cancers of the reproductive system.
for Unmanned Aerial Vehicles.
Towards enabling a UAV to autonomously sense and avoid moving obstacles, this thesis makes the following contributions. Initially, an image-based reactive motion planner is developed for a quadrotor to avoid a fast approaching obstacle. Furthermore, A Dubin’s curve based geometry method is developed as a global path planner for a fixed-wing UAV to avoid collisions with aircraft. The image-based method is unable to produce an optimal path and the geometry method uses a simplified UAV model. To compensate
these two disadvantages, a series of algorithms built upon the Closed-Loop Rapid Exploratory Random Tree are developed as global path planners to generate collision avoidance paths in real time. The algorithms are validated in Software-In-the-Loop (SITL) and Hardware-In-the-Loop (HIL) simulations using a fixed-wing UAV model and in real flight experiments using quadrotors. It is observed that the algorithm enables a UAV to avoid moving obstacles approaching to it with different directions and speeds.
This thesis proposes an extension of David Lewis's causal influence account of causation, providing a method to calculate the `degrees of causal influence.' By providing a quantitative approach to causal influence, I find that that the influence approach can assess statements that involve causal redundancies, allowing the assessor to attribute primary causal responsibility to the contending cause with a higher net influence value. The causal influence calculation also addresses criticisms towards Lewis's influence account, namely those involving `inert zones' of influence, the use of the term `might,' trumping versus symmetric overdetermination, and Lewis's clause requiring stepwise influence. This thesis also compares the results of causal influence in multiple toy cases including Two Rocks, both the asymmetric and symmetric variants, demonstrating that causal influence overcomes many of the core issues in Lewis's initial counterfactual account of causation. Using the asymmetric Two Rocks variant, this thesis also provides a detailed example of how to use the calculation and a discussion of the calculation's limitations. The main drawbacks of the quantitative method for causal influence seems to be the effort that it requires and issues in finding measurable qualities to compare the similarity/difference between possible worlds. Using the Two Rocks case, however, the causal influence calculation reaches the same conclusions as what Lewis suggests. A primary remaining issue is applying the calculation to instances of causation by omission, however this seems to only be a problem in using the equations rather than a problem within the idea of causal influence itself. Also, there may still be issues in justifying comparative overall similarity. However, this is an issue that both the counterfactual and influence accounts face.