Truth and Determinism. Notes for the History of a Pseudo-Problem (original) (raw)

2022, Presented at the SIFA International Conference, Alghero, September 26-28, 2022

In a series of writings from 1918 to 1946, Jan Lukasiewicz provided arguments for logical determinism, that is, the idea that every future event would be determined in advance (as subsistent or nonsubsistent) by the truth or falsity of the proposition expressing it: this fact would a priori limit our ability to influence the course of future events through our free choices. The rejection of 'logical coercion' and the desire to guarantee a scope for our free actions constitute the philosophical motivations that led Lukasiewicz to get rid of the principle of bivalence and introduce a third logical value (the 'possible' or 'indeterminate'), inaugurating the field of polyvalent logics. The kind of argument Lukasiewicz advanced in support of the nexus between bivalence and determinism has a very long history, which Lukasiewicz knew well as he was also an (eminent) historian of logic. The seminal text for logical determinism is the well-known Chapter 9 of Aristotle's “De interpretatione” in which the author suggests that an unrestricted application of the principle of bivalence to contingent sentences expressing future facts would entail a limitation of our freedom. The purpose of this paper is not to offer a historical reconstruction of the problem, rather to show how the use of certain conceptual tools developed within the 'analytic' tradition enable us to dissolve the problem. If my argument turns out to be correct, this will be an example of how a pseudo-problem can be debated in the history of philosophy for over two thousand years just because the meaning of the terms in which it is posed is not sufficiently defined. The main thesis I intend to support is that there is no entailment between classical logic and a deterministic worldview - contrary to Lukasiewicz's claim. In other words, an unrestricted acceptance of bivalence has no bearing on our ability to affect the course of future events through our free choices. In order to argue for this, certain premises are necessary. Primarily, that truth consists in some form of correspondence to reality. A shift from the semantic dimension to the ontological dimension is essential for the determinist argument. I will try to show how within a coherentist, deflationist or pragmatist conception of truth the problem of logical determinism cannot even be formulated. Moreover, I will argue that the problem of logical determinism can be posed only after a clear choice has been made regarding possible truth-bearers, essentially: propositions, sentence-types and assertions. In the first two cases, the temporal dimension is absent: this makes the very formulation of the determinist thesis impossible (as it relies on expressions such as “A is true at time t”). Assertions, on the other hand, are intrinsically linked to a speaker uttering them in a spatial-temporal context. In this case, they are inadequate to fully express the generality logical determinism. Following some reflections offered by Gilbert Ryle (1966) I will show that the so-called problem of logical determinism hides at its core a conceptual confusion between causality and logical consequence: a truth can imply another truth but it cannot be the cause of any event.