With wavering steps does fickle fortune stray,
Nowhere she finds a firm and fixed abode;
But now all smiles, and now again all frowns,
She's constant only in inconstancy.
I am not a positivist. Positivism states that what cannot be observed does not exist. This conception is scientifically indefensible, for it is impossible to make valid affirmations of what people 'can' or 'cannot' observe. One would have to say 'only what we observe exists,' which is obviously false.
Common sense invents and constructs no less than its own field than science does in its domain. It is, however, in the nature of common sense not to be aware of this situation.