Bulls And Bears Duking It Out Morningstar Meeting Oelschlager takes on Grantham for the hearts and minds of investors.(MUTUAL FUNDS)

Byline: PAUL KATZEFF

Like a Roman circus pitting a bull against a bear in mortal combat, Tuesday's opening session of the Morningstar Investment Conference got off to a rousing start as growth and tech bull manager Jim Oelschlager squared off in a debate against noted bear Jeremy Grantham.

The topic: prospects for a rebound in the beleaguered tech sector.

Tech's ability to fuel productivity gains throughout the economy makes its rally inevitable, said Oelschlager, who is chief investment officer of Oak Associates.

Grantham countered that tech will suffer more share-price cuts. That's because the overall market can't sustain current valuations, which are unjustifiably high.

That will force the market to revert to its long-term …