England fly to Auckland on Monday night on the back of a confidence-boosting 20-9 win at the Aviva Stadium - their first in Dublin since the World Cup-winning year of 2003.
Johnson, who was captain on that occasion, is far too practical a thinker to even consider the prospect of history repeating itself.
"You don't win World Cups by thinking about winning World Cups," he said pointedly.
But Johnson is confident that a tough workout against Ireland - and all the injury disruption England had to overcome along the way - proves they are ready for Argentina a week on Saturday.
"You want to win games and this is a tough place to come and win," said Johnson.
"There was a bit of angst around after the last performance (against Wales) because we threw a Test match away.
"We needed to perform and step up, which we did. That's why we wanted to play a game like this one, because that's what World Cup games are like.
"They are tough and we got what we wanted.
"It just demonstrates to us, if we ever have doubts, that when we go and do what we talk about doing, it's effective and we're a pretty decent team."
Judging by the quality of rugby on show when Australia beat New Zealand to win the Tri-Nations title earlier on Saturday, England will need to be better than pretty decent at the World Cup.
Australia played at an electric pace with an invention and ambition that sat in stark contrast to the laboured, one-dimensional performance England had produced in that Cardiff defeat.
Johnson's men will never take the risks of a Quade Cooper - but they went some way to correcting their attacking flaws against Ireland, helped by the reintroduction of the Anglo-Samoan juggernaut Manu Tuilagi into a rejigged midfield.
Tuilagi lined up alongside Mike Tindall in England's 13th different centre partnership in the 35 Tests since Johnson was appointed. He has found the right solution just in time.
Tindall, panned by the critics for his performance in Cardiff, was shifted to inside centre and produced one of his most authoritative England displays for some time.
Tuilagi has been described by Johnson as a "difference-maker" and he proved it again, scorching past Keith Earls to score the opening try after five minutes.
With the England players to sit in alphabetical order on their flight to New Zealand, Tindall and Tuilagi will have 26 hours to get to know each other even better.
"It's great playing next to him. If you're in any doubt just give him the ball!" said Tindall.
"He's a physical specimen who can create anything from nothing."
Elsewhere, James Haskell gave England some dynamism at number eight and Johnson confirmed he is beginning to apply genuine pressure on Nick Easter, who was withdrawn from the game as a precaution over a tight calf.
England adapted well to the early loss of Hendre Fourie, with Courtney Lawes moving to the back row and Tom Croft to openside flanker.
Prop Andrew Sheridan was back in the groove immediately after a four month lay-off and England's defensive performance was rock solid, aided by bench contributions from Tom Palmer and Matt Stevens.
England still need to get their back three into the game more - Ben Foden and Chris Ashton both had quiet afternoons - but the victory has given the whole squad a boost before boarding.
"It's massive, you can't underestimate the value of going over there with a win," said Tindall.
"Everyone will get on (the plane) a little bit buzzing.
"Hopefully that will grow and it can continue growing through the tournament."
Injuries remain a concern - "I don't sleep at night," joked Johnson - but England expect to travel with their full complement to Auckland.
Johnson remains confident his squad captain Lewis Moody and scrum-half Ben Youngs are on target to feature against Argentina as they recover from knee injuries.
Tom Wood and Easter were both withdrawn from the original 22 to Ireland as a precaution over minor calf problems, while Mark Cueto suffered a back spasm in the first half.
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