Why Goldman Sachs' call for a new bull market rings hollow

Goldman Sachs (GS) is making headlines again, this time for two macro calls on the economy. Jan Hatzius, Goldman's Chief U.S. Economist, raised his target for GDP growth in the second half to 3.0 percent from a prior target of 1.0 percent. At the same time, Abby Joseph Cohen, the firm's senior investment strategist, said on CNBC that, "we do think the new bull market has begun," and predicted that the S&P 500 will rise an additional five to 10 percent this year to trade in a range of 1,050 to 1,100.

"Clearly, many people were looking for better signs on the economy, and we're now getting them. Not every sign is positive, but we've seen an upturn . . . the labor news is better, it's still not good, but it's better than it was," Cohen said. The Labor Department announced today that job losses in July came to 247,000 -- the lowest number of the year -- and the unemployment rate dipped.

But just because Goldman Sachs is the most profitable firm on Wall Street doesn't mean their calls should be accepted without scrutiny. And in this case, their reasoning is not bulletproof.