Will S&P 500 earnings really decline?

Analysts expect S&P 500 earnings to decline 5 percent in the first quarter compared to the same quarter last year.

Brian Belski, chief investment strategist at BMO Capital Markets, thinks the forecast is "bunk". He told CNBC that US companies are under-promising earnings so that they can over-deliver.

On the whole, Belski is bullish on stocks, thinking that we are six years into a 20-year bull market.

In contrast, Ashwani Kaul, CEO of Kaul Advisory Group, sees S&P 500 earnings falling 4.6 percent. The silver lining, however, is that earnings are expected to grow 5 percent excluding energy and materials and that overall earnings should turn back up after one or two quarters.

In any case, a period of earnings declines can still turn out to be positive for stocks.