Page "Truth-conditional semantics" Paragraph 5

Under its traditional formulation, truth-conditional semantics gives every necessary truth precisely the same meaning, for all of them are true under precisely the same conditions ( namely, all of them ).

And since the truth conditions of any unnecessarily true sentence are equivalent to the conjunction of those truth conditions and any necessary truth, any sentence means the same as its meaning plus a necessary truth.

For example, if " snow is white " is true iff snow is white, then it is trivially the case that " snow is white " is true iff snow is white and 2 + 2 = 4, therefore under truth-conditional semantics " snow is white " means both that snow is white and that 2 + 2 = 4.

That is wrong.