The same reasoning can be applied to a figure of 10% or 25%. I can't see that working out well. There's a nice paper in 2016 on the OECD web-site by Fournier and Johansson which finds that "Reducing the share of pension spending in primary spending yields sizeable growth gains with no significant adverse effect on disposable income inequality. This reduction could be achieved by an increase in the effective retirement age or by cutting the replacement rate" and "Increasing the share of pension spending in primary spending by one percentage point (offset by a reduction in other spending) would decrease potential GDP by about 2%." But if that doesn't convince you the triple lock is a bad idea, consider the effect on the lefties favourite theme of inequality. The low income pensioner loses 85% of any net increase due to the taper rates of Housing Benefit and Council Tax Reduction. The highest income pensioners lose 45, 40 or 20% of the net increase.