Empiricism and Rationalism in the Advancement of Astronomy Odysseus Quarles Undergraduate Honors Thesis in Astrophysical and Planetary Sciences University of Colorado Boulder Thesis Defense Date: March 20, 2018 Advised by: Thesis Advisor: Asst. Prof. Dave Brain, Ph.D. Department of Astrophysical and Planetary Sciences Honors Council Representative: Asst. Prof. Ann-Marie Madigan Ph.D. Department of Astrophysical and Planetary Sciences Third Reader: Assoc. Prof. Dominic Bailey, Ph.D. Department of Philosophy Abstract Astronomy is advancing quickly, with resources being allocated to the cutting edge of our understanding of the universe while the more basic understanding and confirmation aspects of astronomy research are still underway. Research in both areas is conducted according to two differing philosophies of knowledge: empiricism, which holds observation and direct experiment as the most reliable source of information, and rationalism, which holds conclusions reached through pure reasoning from first principles above all others. This investigation seeks to explore how the empiricist and rationalist approaches each serve the pursuit and advancement of astronomy as a science. Using a thorough analysis of the existing literature on empiricism and rationalism in astronomy, as well as data from interviews of several practicing expert astronomers in and around the University of Colorado Boulder who take empiricist and rationalist approaches to astronomy research, this investigation finds that astronomy as a productive, growing field of research achieves its greatest successes when empiricists and rationalists can work in close proximity. Increased communication and collaboration between researchers of the two approaches, as well as a stronger understanding of the applications and implications of empiricist and rationalist thought, can help to maximize these advantages. Table of Contents Introduction ....................................................................................................................................1 Purpose .................................................................................................................................1 Definition of Terms..............................................................................................................2 Investigative Methodology ..................................................................................................3 Basic Background ................................................................................................................4 History .............................................................................................................................................7 Copernican Revolution: Birth of Scientific Astronomy ......................................................7 Philosophy..........................................................................................................................10 Modern Day Astronomy ..............................................................................................................15 Interviews ...........................................................................................................................16 Trends from Interviews ......................................................................................................22 Conclusions ...................................................................................................................................26 References .....................................................................................................................................29 Special Thanks to Interviewees...................................................................................................30 Appendix 1: Interview Response Summaries ............................................................................31 Quarles Empiricism and Rationalism in the Advancement of Astronomy 1 Introduction Purpose While scientific research is typically characterized as investigation into the nature of the world according to the scientific method, various incarnations of the scientific method have been used as tools for discovery and learning. Equipped with our senses, humanity has witnessed and recorded countless events and phenomena – yet observation is but one step of the process. Far more than our senses, the pursuit of science demands the use of our wits. In fact, parallel to the more commonly recognized school of empiricist science, which relies upon observation and experimentation to achieve results and draw conclusions, there is the school of rationalist science, governed only by reasoning and inferences made from prior knowledge. There is a longstanding debate in the philosophy of science regarding the merits and limitations of each. Of all the sciences, it is astronomy that is affected most profoundly by this debate. The nature of astronomy, with a subject matter so broad, so large, and so distant that direct experimentation akin to studies of chemistry or medicine is in essence impossible in many cases, dictates that an empiricist pursuit of astronomy is highly limited. At the same time, the vast majority of accepted physical models of the universe in the last few centuries have assumed a universe governed by laws that apply as well to the largest and most distant galaxies as they do to ten-kilogram projectiles fired off the back of fifty-kilogram carts in high school physics textbooks. This homogeneity greatly eases and enhances the scope of the discoveries, or at the very least the reasonable inferences, that can be made via rationalist thought. Quarles Empiricism and Rationalism in the Advancement of Astronomy 2 This investigation examines the extent to which astronomy as a scientific pursuit benefits from a rationalist approach as compared to an empiricist one. These two schools of thought are not necessarily mutually exclusive, but instead may be codependent and often build on one another. This paper is concerned with that particular interaction between rationalism and empiricism, as both are used extensively to expand the current body of knowledge in astronomy. In order to assess and compare the relative breadth and effectiveness of either approach, it is not sufficient to simply compare the results of each; it is instead necessary to examine their relative strengths and weaknesses, and apply those to the needs of astronomy today. This investigation hypothesizes that while empiricism provides a necessary step in the advancement of astronomy by confirming rationalist theory and providing new questions to be explored, the bulk of new advancements in astronomy comes from the rationalist approach. Definition of Terms In order to present a coherent and meaningful discussion of the merits of rationalism and empiricism in the context of astronomy, certain critical terms require definition. For the purposes of this paper, these definitions are as follows: Rationalism: Merriam-Webster defines rationalism as “a theory that reason is in itself a source of knowledge superior to and independent of sense perceptions.” In the context of astronomy, this denotes an approach to research that is built around known natural laws and the basic principles of mathematics. In a purely inductive epistemology, the basic principles of mathematics and a simple understanding of natural law are sufficient to predict and describe all possible natural phenomena, independent of any observations. An astronomer who practices rationalism is a rationalist. Quarles Empiricism and Rationalism in the Advancement of Astronomy 3 Empiricism: Again using the Merriam-Webster definition, empiricism is “the practice of relying on observation and experiment especially in the natural sciences.” In contrast to rationalism, empiricism holds observational data above inductive reasoning. Even if a hypothesis is mathematically proven beyond doubt, a strict interpretation of empiricism demands that conclusive observations be made. An astronomer who practices empiricism is an empiricist. Theory: A scientific theory is the generally accepted description or explanation of a natural phenomenon. The theory of a phenomenon can predate or be more in-depth than its observation. Theories in astronomy are typically heavily grounded in mathematics and computer models, and as such are associated with the rationalist school of thought. A theorist is an astronomer who manipulates and develops theory. Theorists are rationalists. Observation: Observation is the practice of collecting data on a natural phenomenon, typically for the purpose of better understanding it or similar phenomena. Observation can predate theory, though this is rarer than the reverse since theory is not subject to the same strict technological limits of observation. An astronomer who practices observation is an observer or an observationalist. Observers are empiricists. Investigative Methodology This investigation focuses on the potential for growth in the current body of knowledge, and as such takes into account recent advances and trends such as gravitational wave observations and the ongoing explosion of exoplanet research. However, as the present does not exist in a vacuum, certain critical results of the recent and historical past of astronomy research (primarily, the Copernican Revolution and the implications of 20th century space-time theories) Quarles Empiricism and Rationalism in the Advancement of Astronomy 4 are also considered. Initial and preliminary research