England face Argentina at Twickenham unbeaten at home since the 2015 World Cup having won 20 of their last 21 Tests.
It is a run which has taken them to No 2 in the world but Hartley feels second best is nowhere – and he is not afraid to say so.
“The belief is 100 per cent there now in the team that we can get to No 1 and we can win a World Cup,” said the bullish England captain.
“If you don’t have these kind of goals, these dreams, and you don’t talk about these things, I don’t think you’ve got any chance of achieving them.
“In the past, we were too polite but it’s sport, it’s a challenge. We want to win everything.”
England will target Argentina’s traditional strength – their scrum – to try to break opponents who they have beaten three times in the last year and who they face again in the group at Japan 2019.
“It’s what makes them tick so if we can put pressure there, it could tell in other areas of the game,” said Hartley.
The Pumas have won just three of their last 20 Tests, a sequence which led England coach Eddie Jones to claim his opposite number Daniel Hourcade was under pressure this week.
“You are always under pressure at the top level. The pressure is perhaps more on England,” countered Hourcade.
“They are No 2 in the world, we are number 10. We are playing here, in the last part of our season. If we lose, it would be logical but if they lose, it wouldn’t. They have the pressure.
“We all know how Eddie is – perhaps some things he says are not true.
“England are a complete team, really efficient, but they have some weak points. The strategy will be to attack those weak points.”
England will be wearing their new dark grey change strip for the match which manufacturers Canterbury claim is: “inspired by distraction principles” that “make it harder to distinguish aspects of the body during the tackle”.
The invisibility cloak is their eighth different kit in the last three years and at £95 its introduction has has led to accusations of commercial cynicism by the RFU.
“We have an alternative kit every year – the shirts are popular with fans and the money we raise from sales goes back into the game of rugby,” said an RFU spokeswoman.