Explain, using a concrete example, why we should not allow the following inference when using $\textbf{ EI }$ . What restriction then is required on the use of $\textbf{ EI? }$

Question

Explain, using a concrete example, why we should not allow the following inference when using $\textbf{        EI }$ . What restriction then is required on the use of $\textbf{     EI?    }$

Quizplus · Accepted Answer

The Answer is It could allow us to move from a true statement to a false one. For example, if Lxy = "x loves y", then from the fact that x loves someone it does not follow that x loves him or herself. EI requires that the variable replacing the variable made free with the removal of the existential quantifier be one that is not free earlier in the proof (restriction 2).

Explain, Using a Concrete Example, Why We Should Not Allow EI \textbf{ EI } EI

Explain, Using a Concrete Example, Why We Should Not Allow $\textbf{ EI }$