The duo have both impressed this season for Portuguese table toppers Benfica, who are unbeaten so far in all competitions and qualified from their Champions League group ahead of Paris St Germain.
Silva has been one of Europe's breakout players this season after forcing his way into Benfica's starting team after injuries to Morato and Lucas Verissimo.
In-form Ramos has helped Benfica fans quickly forget former forward Darwin Nunez (23), who joined Liverpool in the close season, scoring 12 goals in all competitions, with coach Santos choosing him over Wolves forward Goncalo Guedes (25).
Led by Cristiano Ronaldo (37), Portugal's squad will be on paper one of the best competing in Qatar.
"We have a team capable of winning it all, that is what this group is capable of," Santos told a news conference in Lisbon on Thursday.
"The players are hungry and will give it all to make Portugal the world champions.
"Our list was based on the players' qualities and potential, on what each one of them can offer to our system."
Santos said he is not worried about criticism aimed at captain Ronaldo, whose struggles at Manchester United this season have raised questions about whether his brilliant career is nearing its end.
"If we talk about momentum, Ronaldo has played the last four games with his club," Santos said.
"So I'm not concerned. We'll try to understand the best ways to boost all the players in our system, including Ronaldo."
The Man United forward issued a rallying cry on social media.
"Once again we are ready to uplift the name of Portugal! There are 26 names in coach Fernando Santos' list, but we are all called upon. Let's go, Portugal!" Ronaldo wrote on his Instagram account.
Portugal Squad
Goalkeepers
Diogo Costa (FC Porto)
Jose Sa (Wolverhampton Wanderers FC)
Rui Patricio (AS Roma)
Defenders
Diogo Dalot (Manchester United)
Joao Cancelo (Manchester City)
Danilo Pereira (Paris St Germain)
Pepe (FC Porto)
Ruben Dias (Manchester City)
Antonio Silva (SL Benfica)
Nuno Mendes (Paris St Germain)
Raphael Guerreiro (Borussia Dortmund)
Midfielders
Joao Palhinha (Fulham FC)
Ruben Neves (Wolverhampton Wanderers)
Bernardo Silva (Manchester City)
Bruno Fernandes (Manchester United)
Joao Mario (SL Benfica)
Matheus Nunes (Wolverhampton Wanderers FC)
Vitinha (Paris St Germain)
William Carvalho (Real Betis)
Otavio (FC Porto)
Forwards
Cristiano Ronaldo (Manchester United)
Joao Felix (Atletico Madrid)
Rafael Leao (AC Milan)
Ricardo Horta (SC Braga)
Goncalo Ramos (SL Benfica)
Andre Silva (RB Leipzig)
