Saxons coach Jon Callard has made eight changes to the starting line-up from last weekend's 23-17 victory over the Ireland Wolfhounds in Exeter.
Bath full-back Nick Abendanon replaces Delon Armitage, who has been suspended from the Saxons elite player squad following his arrest on suspicion of assault, and Northampton's Ryan Lamb takes over from Freddie Burns at fly-half.
Joseph comes into the midfield for Matt Hopper, where he will partner Leicester's Billy Twelvetrees, while Gloucester's Jonny May starts on the wing in place of Matt Banahan.
In the pack, Slater replaces London Irish lock Matt Garvey, Gloucester prop Nick Wood and Harlequins hooker Chris Brooker get starts in the front row and Exeter's Tom Johnson takes over from Thomas Waldrom at number eight.
"We need to back up that performance against the Wolfhounds by getting it right away from home against Scotland this week," said Callard.
"The endeavour and energy we showed last week at Exeter was first class but not everything was absolutely spot on and we need to improve our accuracy and execution.
"We always planned to make changes over the course of these two games and it means there are more chances for those who've been playing well in the Aviva Premiership and in Europe this season."
Sale full-back Rob Miller and Bath prop Kane Palma-Newport will travel to Scotland with the squad as cover.
England Saxons team to play Scotland A: N Abendanon (Bath Rugby); U Monye (Harlequins), J Joseph (London Irish), B Twelvetrees (Leicester Tigers), J May (Gloucester Rugby); R Lamb (Northampton Saints), B Spencer (Saracens); N Wood (Gloucester Rugby), C Brooker (Harlequins), P Doran-Jones (Northampton Saints), E Slater (Leicester Tigers), G Robson (Harlequins), J Gaskell (Sale Sharks, capt), A Saull (Saracens), T Johnson (Exeter). Replacements: J Gray (Harlequins), R Harden (Gloucester Rugby), K Myall (Sale Sharks), D Seymour (Sale Sharks), P Hodgson (London Irish), F Burns (Gloucester Rugby), M Benjamin (Worcester Warriors).