we had a disscussion on Laffer on this site a couple of years back (unfortunately I can't seem to go that far back in post history)... Laffer IS a hack.
He made a name for himself in the late 1970s by putting his name on a concept that was in discussion at the time, and having it stick. the "Laffer curve" is a construct that shows that if you increase the tax rate two effects occur:
1> revenues go up because you are getting more taxes for every dollar spent
2> revenues go down because there is more disincentive to work (so you are gathering taxes from a smaller pie). )
the laffer curve is plotted with tax revenue on the y axis and tax rate on the x axis and it shows an upward sloping curve for the most part, but at high enough tax rates it is possible for 2) to actually be bigger than 1) so for most of the curve increasing tax rates increases revenue, but at a high enopugh tax rate increasing tax rate further actually decreases revenue)
BUT there has been considerable economic empirical analysis into locating the point where the "laffer-curve" flips (ie the tax rate above which a tax cut actually increases revenue) and it is EXTREMELY high in every single study... much higher than the tax levels we have in the US. much MUCH higher (orders of magintude higher).
the laffer examples up above are plain bad economics: the economy grows over time. period. Both in real terms, but even more so in nominal (dollar) terms. to say:
"we had a tax cut in 1982, and revenues wer much higher in 1990, ergo the tax cuts raised revenue"
is at best sloppy. (that is being damn kind). you HAVE to at least TRY to empirically account for other things that occurred over the same time period, no?
here is a good, straightforward, analysis of similar arguments from the current administration:
http://www.cbpp.org/9-27-06tax.htm