Deduction is a bad idea which Popper accepted. The idea is that certain arguments are “deductively valid”. A valid argument is one such that if the premises are true then the conclusion MUST be true. Deduction thus has an anti-fallibilist character because it seeks certain knowledge about the implications of premises.
Deductivists believe that we can create valid arguments, and we can evaluate whether arguments are deductively valid or not. They believe philosophers accurately do this dozens of times in their life. Validity isn’t an impossible ideal but is within our grasp. This implies that violating fallibility can be done routinely.
Note: This is not an attack on logic in general. We can and do have conjectural knowledge of logic, the implications of premises, and so on.