In the help tips (VIew Space Permissions), it seems like there's an inconsistency.

Extract:

These permission types are available:

1. View Space: user can view space details and view and edit its pages.
2. Leave Comments: user can leave comments with existing pages.
3. Modify Space: user can edit pages in a space, add and remove pages, delete comments and upload attachments.
4. Administrate Space: user can set permissions for the space, and edit the space's description.

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It seems like the View Space permission should be changed into

user can view space details and view its pages.

Otherwise it conflicts with modify space.

Note: I haven't tried to edit pages on a confluence install where users are only given the VIew Space permission. I am maybe wrong. But if I am, please tell me why both the View Space and the Modify Source permissions allow one to edit a space.