The two basic reasons why economists often appear to give conflicting advice to policymakers are differences in

Scientific judgement and value

Explanation:

Values are the set of believes and convictions that shapes individual's character, personality, judgement and opinion. The value system of an economists will surely shape is opinion in public issues, even it will also influence his or her advice to policy makers.

Scientific judgement is judgement based on the outcome of a conclusion derived from scientific analysis. this is an informed judgment as opposed value judgement.