[Piers]

I think there is a trick you can use

Not A !or Not B = A !or B

So how about:

People either use some sort of induction deduction combination or they use evidence.

Or maybe even

If people use some sort of induction deduction combination, then they are not using evidence.

(Well clearly they are using evidence, but the evidence is indirect. The evidence they used as a basis for their induction, or the evidence they used as a parameter in their deduction.)