Abstract

In the first part of the article true expressions and false expressions are presented that served A. W. Burks to build a formal system of logic of causal propositions along with considering their later use in the system built in 1963. In the second part of the article the possibility of conducting an axiomatic proof of the theorem on adding a superfluous condition is analyzed. The consequences are also shown of substituting a negation of the same prepositional variable for the propositional variable and conditions are analyzed of substitution for propositional variables and possibilities of avoiding those difficulties