The issue they have in common is whether or not additional fiscal expenditure will exert positive effects on the way people form their positive expectations in a sustainable manner. Households do not act as rationally as Ricardian equivalence assumes.
Meanwhile, it also is plausible to assume that their concerns over possible tax hikes and an increase in social security tax burden provide a reason for their cautious outlook. These arguments might have given rise to the idea that it is desirable to have permanent fiscal policy expansion without an accompanying future tax hike.