Full Idea
Ockham's Razor is the principle that we need reasons to believe in entities.
Clarification
'Entities' are just things which exist
Gist of Idea
Ockham's Razor is the principle that we need reasons to believe in entities
Source
DH Mellor / A Oliver (Introduction to 'Properties' [1997], §9)
Book Reference
'Properties', ed/tr. Mellor,D.H. /Oliver,A [OUP 1997], p.22
A Reaction
This presumably follows from an assumption that all beliefs need reasons, but is that the case? The Principle of Sufficient Reason precedes Ockham's Razor.