The Hoops are overwhelming favourites to retain their title with their former Old Firm rivals set to play in the Third Division.
Ahead of Saturday's game against Inter Milan at Celtic Park, the last friendly before the first leg of their Champions League third-round qualifier against HJK Helsinki at Parkhead next Wednesday, the Celtic keeper was asked if the SPL title is now devalued.
"Not at all," he said. "If you win the league you win the league.
"It is a fantastic opportunity for the other teams in the league to go for that second place or compete for the league."
When it was pointed out that his first thought was to talk about who would come second, echoing the sentiments of all the other clubs in the SPL, Forster said: "That's up them to be honest.
"Realistically everyone should be setting out hoping they can win the league, if you don't think you can win the league you never will.
"We will go out and be positive and play against whoever we play against.
"The league is important and it will mean as much winning it this time as winning it last year."