You need conviction for these tough times, Jim Cramer told "RealMoney" radio show listeners Tuesday, criticizing an analyst for downgrading a stock on investor sentiment. It's not worth it to sell Halliburton ( HAL) just because investors are leaving the market, he said. Cramer owns Halliburton for his charitable trust Action Alerts PLUS . There's a lot of research out there that shows that investors may not want to pull out of the market, he added. For example, Cramer has a huge amount of faith in the infrastructure sector, but this is the sector that has taken the worst beating. Cramer believes that in 18 months, this sector will be in inning three or four, but he sees that it's hurting now. This is in large part because Shaw Group ( SGR) reported a very disappointing quarter. The stock plummeted, and it created some unfortunate pin action that affected every infrastructure stock. Jacobs Engineering ( JEC) then said that its infrastructure earnings will likely grow by 30%; the stock at one point today was up 8 points. Cramer said this ignited the sector and put space between the Shaw disaster and the rest of the sector. He said that McDermott International ( MDR) is a "fine company" involved in the engineering and construction business, but that the stock is not that cheap. Fluor ( FLR) is the "premier, big daddy of infrastructure," which is at $86, down from a high near $103. Cramer owns three infrastructure plays, including Foster Wheeler ( FWLT), which he said is the worst performer in his Action Alerts PLUS portfolio. But if you have conviction about the fundamentals that isn't a problem, he said. He also owns URS ( URS), which does engineering and construction for the U.S. government and has a hazardous-waste management unit. And Cramer owns ABB ( ABB), the largest engineering construction company in Europe. Speaking of conviction and sentiment, Cramer pointed out that Nabors ( NBR), which he owns for his trust, Action Alerts PLUS , is down and causing short-term pain because the analysts hate the stock now that natural gas prices have sunk. Even though coal and deep-water oil drilling seem like sexier plays, he said that Nabors should not be overlooked. The stock has gotten so hammered, he said, adding that a company can fall so low it becomes too cheap to ignore, whether it's a gas driller or a bubble-gum maker. Moreover, Cramer said he has conviction that the stock's fundamental story is still intact because we are not going to stop using natural gas. To see the most recent edition of The RealMoney Radio Recap in its entirety, please click here. This recap is published every day around 3 p.m. ET.