(Cf. Locke on "tabula rasa.")

Arguments for the thesis:

1. Analysis:

"[W]hen we analyze our . . . ideas . . . we always find that they resolve themselves into such simple ideas as were copied from a precedent feeling or sentiment [i.e. an impression]." (IP3 106b)
Example: our idea of God

2. Defect of Organ:

"If it happen, from a defect of the organ, that a man is not suscepible of any species of sensation, we always find that he is as little susceptible of the correspondent ideas." (IP3 106b)
Example: man born blind

Notice that argument (1) applies to complex ideas and argument (2) to simple ideas.