This may be a really dumb question but...
no such thing if you don't know the answer
1]How do you know what position you're in?
2] I know most of the positions of the scales
3] but you can move all the scales around the fretboard?
4] It's not like each position has a specific part of the fretboard right?
5] Is it because you're transferring to the root note of a different position?
6] Because couldn't you just slide anywhere and continue playing the notes of a different scale?
1] by referring to the position of the root note within the pattern of that position ... Justin teaches 5 positions and each has the root note in a unique place in the pattern
2] which scales? major and minor pentatonic?
3] yes you can move scales horizontally along the neck until you run out of room
4] yes they do but if you think octaves most positions repeat higher up the neck too... for example .. minor pentatonic position 1 in A only sits at frets 5-8 as taught here http://www.justinguitar.com/en/BL-012-BluesScales.php
and because the guitar neck has octaves it also sits at frets 17-20
5] the root note can be of great help in guiding you but you do need to be able to make transitions from position to position in other ways too ... for example http://www.justinguitar.com/en/BL-018-LinkingPos1Pos2.php
6] that's why you should practice scale positions and moving between scale positions and playing the scale notes on single strings, adjacent strings etc, practice them vertically across the neck as patterns and up and down the neck horizontally ... if you're not sure about this then this thread is a good place to get more info http://www.justinguitarcommunity.com/index.php?topic=10992.0