Lewisian analysis of objective probability: An origin of the undermining futures

Abstract

David Lewis’ interpretation of objective probability has two essential parts: Humean supervenience and Best system of laws. According to his interpretation, probabilities, along with the other nomic phenomena, supervene on the actual facts. Lewis also famously formulated the Principal Principle, which should show the connection between objective and subjective probabilities. However, years later, Hall, Thau and Lewis himself came to conclusion that the principle and Lewis’ interpretation of probability are not compatible. The main reason for that is the problem of so called undermining futures: Lewis named the problem „Big Bad Bug“. A popular way to solve the problem was to change the principal principle. In this article, I will argue that the origin of the problem is not compatibility of the principle and Lewis’s interpretation of probability, but that the problem is in the interpretation itself. Changing the principle, I argue, will not conclusively solve the problem.

Dejvid Luis je izneo interpretaciju objektivnih verovatnoća koja se zasni- va na idejama hjumovske supervenijencije i najboljeg sistema zakona. Prema njegovoj interpretaciji, verovatnoće, zajedno sa ostalim nomičkim fenomenima, superveniraju na aktualnim činjenicama. Luis je, takođe, formulisao osnovni princip, koji bi trebalo da nam pokazuje vezu između objektivnih i subjektivnih verovatnoća. Ipak, Hol, Tau i sam Luis, kasnije su došli do zaključka da Osnovni princip i luisovska interpretacija vero- vatnoća nisu kompatibilni zbog problema podrivajućih budućnosti: problem koji je Luis nazvao „Velika Zla Buba“. Popularan način rešavanja tog problema bio je menjanje osnovnog principa. U ovom radu izneću argumente u prilog teze da uzrok problema nije spajanje osnovnog principa sa luisovskom interpretacijom verovatnoća, već se problem nalazi u samoj interpretaciji verovatnoća. Menjanje principa, prema mišljenju koje ću zastupati u ovom radu, neće doprineti konačnom rešenju problema.