Probability and certainty: A reexamination of the Lewis-Reichenbach debate

Conclusion

I have shown as promised that Reichenbach did not refute either thesis (I) or thesis (II). I have also shown that an argument of Lewis's may be used to establish a weakened version of (I) that has two interesting consequences: if we are to assign probabilities with any justification at all, we must have either certainties or intrinsic probabilities; and if we are frequentists, we must have certainties.