Ramsey´s Probability Theory of Truth

Truth is one of the most important and widely discussed topics in philosophy. Todays debate is dominated by various deflationary theories of truth, which all have their roots in Ramseys redundancy theory laid down in Facts and Propositions (1927). Frank Plumpton Ramsey (22 February 1903 --19 January 1930) was one of the most brilliant and notable scholars of the twentieth century. His premature death left his most extensive project, the book On Truth and Probability unfinished. Even though, Ramsey showed that the predicate is true can be eliminated from certain propositions without effecting their meaning, he considered his theory to be a correspondence theory of truth. His goal was to present a logical analysis of the terms judgement and belief which did not presuppose the concept of truth. These notions, together with other essential concepts, are scattered throughout his essays lacking systematic and conclusive analysis. For various reasons Ramseys work has not been granted much attention leaving his unique ideas undiscovered. Ramseys essays constitute a material for the discussion of significant philosophical issues at the same time providing a basis for a formal theory of truth. Ramsey maintained that at the bottom of his redundancy theory laid the correspondence theory of truth and that there is a firm connection between this theory of truth and probability theory. No conclusive connection between Ramseys redundancy theory and the correspondence theory on which he was working has been established yet. There is still no theory which encompasses his redundancy and correspondence theories at the same time employing the crucial notions from his essays connecting it to probability theory. No formal theory of truth based on Ramseys theories has been established either. I will thoroughly investigate the relevant notions from his essays and determine their connections as well as their relevance for Ramseys theory of truth. Furthermore, I will investigate into the connections between Ramseys redundancy theory and the correspondence theory of truth at which he was aiming. I will also examine the role which probability theory plays in Ramseys inquiry into the nature of truth. My aim is to determine the connection between Ramsey`s redundancy theory and the correspondence theory of truth, and to establish the link between a theory of truth constructed on the basis of Ramsey`s ideas and his interpretation of probability theory, and thus to present a novel probability theory of truth. Ultimately, I plan to develop a comprehensive formal theory of truth, which combines the two opposite attitudes towards truth: deflationary and substantial at the same time employing probability theory. Such formal theory is the missing link in today`s philosophical debate on truth and probability.

Truth is one of the most important and widely discussed topics in philosophy. Todays debate is dominated by various deflationary theories of truth, according to which to assert that a statement is true is just to assert the statement itself. They all have their roots in Ramseys redundancy theory laid down in Facts and Propositions (1927). There, he showed that the predicate is true can be eliminated from certain sentences without effecting their meaning, for example the statement that Caesar was murdered is true means no more than that Caesar was murdered. Frank Ramsey (22 February 1903 19 January 1930) was one of the most brilliant and no- table scholars of the twentieth century. His premature death left his most extensive project, the book On Truth and Probability unfinished. Ramsey was unsatisfied with a theory that just proclaims the redundancy of the truth predicate and leaves it at that. His project was much more ambitious, for he wanted to determine what it means for a speaker to have a belief that such and such is the case, hence to lay down a theory of meaning and belief. He wanted to combine full and partial beliefs into one theory of belief. An outline of such a theory, is most clearly visible in Ramseys Truth and Probability (1926) and especially in Facts and Propositions. In my investigations I focused on the notions of truth and belief. One possible interpretation is into a modern decision theory. Therefore, I also examined the notion of action and its role in Ramseys uncompleted theory of belief. In his notes, which appeared as a manuscript On Truth in 1991, Ramsey sketches a theory of belief and truth which is infused with pragmatism. We use our beliefs in order to act. If our beliefs are true, they will or at least can lead us to success. Modern decision theory has applications in multiple fields: economics, politics, science and even our every day life. We make decisions all the time, sometimes we are certain they are based on our true belief, and hence should help us accomplish what we want. Other times we are less certain of our judgement, but still have to make a decision whether to act on it or not. We are indebted to Frank Ramseys philosophy, for being able to make a rational decision is such circumstances. At the end of my project, I turned to a recent article by Leitgeb on stability theory of belief, which struck me as a theory Ramsey may have been aiming at. Leitgeb presents a joint theory of full and partial belief, i.e. degrees of belief. He holds that it is rational to believe something if and only if it is rational to have a high enough degree of belief in it. Ramsey too, was determined to bringing the notions of full and partial belief together. More- over, the connection which I believe links Ramseys investigation on truth to his probability theory is precisely the notion of belief, and more specifically, the agents actions based on both full and partial beliefs. Ramseys and Leitgebs investigations on belief are a starting point for my next project in which I aim to reconstruct and complete Ramseys theory of belief.