### Abstract

We develop finitely additive probability logic and prove a theorem of Patrick Suppes that asserts that $\Psi \vdash \phi$ in classical propositional logic if and only if $(\sum \psi \leftarrow \Psi.\; 1 - \mathcal{P}
\psi) \geq 1 - \mathcal{P} \phi$ holds for all probabilities $\mathcal{P}$. We also provide a novel

*dual*form of Suppes' Theorem, which holds that $(\sum \phi \leftarrow \Phi.\; \mathcal{P} \phi) \leq \mathcal{P} \psi$ for all probabilities $\mathcal{P}$ if and only $\left(\bigvee \Phi\right) \vdash \psi$ and all of the formulae in $\Phi$ are logically exclusive from one another. Our proofs use*Maximally Consistent Sets*, and as a consequence, we obtain two*collapse*theorems. In particular, we show $(\sum \phi \leftarrow \Phi.\; \mathcal{P} \phi) \geq \mathcal{P} \psi$ holds for all probabilities $\mathcal{P}$ if and only if $(\sum \phi \leftarrow \Phi.\; \delta\; \phi) \geq \delta\; \psi$ holds for all binary-valued probabilities $\delta$, along with the dual assertion that $(\sum \phi \leftarrow \Phi. \;\mathcal{P} \phi) \leq \mathcal{P} \psi$ holds for all probabilities $\mathcal{P}$ if and only if $(\sum \phi \leftarrow \Phi.\; \delta\; \phi) \leq \delta\; \psi$ holds for all binary-valued probabilities $\delta$.### License

### Topics

### Related publications

- Suppes, P. (1966). Probabilistic Inference and the Concept of Total Evidence. Studies in Logic and the Foundations of Mathematics, 49â€“65. https://doi.org/10.1016/s0049-237x(08)71662-8