Being the first candidate to formally launch a presidential exploratory committee, it looks like is definitely running for president:
THE HILL – Tea Party darling Ben Carson is launching a formal presidential exploratory committee, the first serious candidate to do so, a top aide told The Wall Street Journal.
The exploratory committee, the first official step toward a bid for president, allows Carson to start directly fundraising for a potential bid. Potential candidates informally use their political action committees as the first trappings of a campaign.
By filing with the Federal Election Commission, Carson can cut out the middle-man and start raising money and make staffing decisions for what would become his eventual campaign.
Carson and any other potential candidate has to declare their candidacy if they hit certain thresholds, by FEC rules.
Potential candidates can’t raise more than “reasonably required for exploratory activities,” begin heavily campaigning, advertise their intention to run, or actively seek a spot on the ballot. If they do, they must announce as a candidate.