My stance is that this a nature/nurture kind of debate, to argue either extreme is ridiculous, there are clearly elements of both sides that are true.
No positive/negative turn in the economy can be isolated to a single cause, so neither side will ever be convinced by the others arguments.
A third point, which I think is often lost in these arguments, is that governments have interests that are beyond improving the financial standing of its citizens. A pure market capitalist probably wouldn't think subsidizing farming or shipbuilding a particularly good idea, but the government might be willing to accept some market inefficiency in exchange for food security or having an established ship building industry for times of war. Similarly, high income inequalities may cause high social unrest, it's in the governments own interest to prevent this, so it may be willing to accept lower total nation wealth in exchange for more evenly distributed wealth among its citizens by imposing progressive taxes and creating welfare programs.
Everybody agrees that markets work, the main questions are: are they optimizing for the thing you want? and are there cultural/political externalities that the market doesn't care about but a government might?
When the economy does well:
When economy does poorly: Feel free to repeat this argument for every boom/bust in the past/future