This theory of propositions (PR 184 - 207) is remarkable for the co-author of Principia Mathematica since it abandons its claim that the subjects of logical propositions can be imaginary. (religion-online.org)
8 - 3 equals 5, which is correct but it is a different logical proposition from 2 +3 = 5 yet with the same physical causal sequence. (faith.org.uk)
Gödel's incompleteness theorem of 1931 succeeded in proving that it is impossible, in principle, to set up a system of mathematics by logical propositions which does not imply some propositions which the system is unable either to prove or disprove. (religion-online.org)