Full Idea
If someone claimed a patch of land was tended by a 'gardener', but there was never a shred of evidence to support this view, the claim would gradually dissolve into meaninglessness, especially if it was suggested that evidence was irrelevant.
Gist of Idea
You can't claim a patch of land is tended by a 'gardener' if there is no evidence, and all counter-evidence is rejected
Source
report of Antony Flew (Theology and Falsification [1950]) by PG - Db (ideas)
Book Reference
'The Existence of God', ed/tr. Hick,John [Macmillan 1964], p.225