Open Left

taxation on the wealthy reduces savings = reduces investment
excessive consumption --> inflation in wage goods --> cycle of increasing wages, progressive taxation, and inflation
etc etc etc
taxation on wealth --> disincentive to grow wealthy --> reduced overall risktaking / entrepreneurship / investment --> lower aggregate production

in a nonwealthy economy (i.e. where scarcity of capital is a more serious issue) you have similar arguments but the stakes are upped.  not clear whether or not they're any less stupid but you do have an additional dimension to contend with (societies attached to nonwealthy economies tend to get dominated in global capitalism)

anyway, all of these arguments depend on looking at the actual social context and defining policy accordingly (and in accord with your own beliefs about what makes the most sense - there are certain presumptions that go into all of these things about how people behave and what kinds of social organisation work).  for example, if you have a fairly equal society and demand as a whole is outstripping supply and you're interested in pursuing capitalist growth (this is one of thsoe presumptions) then it would make sense for you to policywise divert some money towards accumulation (whether through the state or the private sector or individuals).

but that is not the situation we're in - we have demand that is too low, excessive inequality (economically - not just politically), failing infrastructure, relative (if slight for now) decline globally, etc - which is why all the policies pursued by the u.s. elite today are so incredibly moronic when taken as a whole if they are interested in the welfare of the united states.  

of course, i come to that conclusion partly because i can't bring myself to believe that they in some sense the financial class is seceding and is just waiting for another market to plow their money into and don't give a f"£k about anyone else.  even though they keep saying that's what they're doing.

and of course, no one seems to notice that their 'choice' leads to public spending in the only area that's politically palatable besides benefits for old people- what's euphemistically called 'defense' - in order to keep society going...and hence we get wars.  because what point are toys, armies, and miliatary bases and entire communities built around them if they're not going to be used?  they have to justify themselves somehow.