[FOM] When is it appropriate to treat isomorphism as identity?

[Alex Blum]

Vaughan Pratt wrote:

>...........
>
>A benefit of mathematical logic is that it makes explicit principles of 
>logic that we might otherwise consider inviolable, allowing us to 
>consider the consequences of violating them by replacing them with 
>competing rules, thereby contributing to the ongoing undermining of the 
>efficacy of pure reason.
>
Is it realistic to think of fol or of sol or their principles as being 
violable if our paramont interest in logic is that inference preserve truth.
Alex Blum