Dear A D:
>
> You wrote:
> a. Freud uses unconscious drives to explain our behaviour.
> b. Marx bases his vision of history on class struggle.
> c. Heisengberg employs subatomic mechanisms to explain the strange
> phenomena we observe.
>
> Are the above sentences logical? Freud doesn’t use unconscious drives, but
> “the idea of unconscious drives”; Marx bases his theories on “the concept
> of class struggle” and Heisenberg employs “the idea or a theory of
> subatomic mechanisms”. Can the words “the concept of…” etc. be
> considered to be implied by the sentences?
>
> Instead of the first sentence can one say: Freud uses the idea of
> unconscious driveS to explain our behaviour?
>
You point is well taken. In conversation and in context, listeners would probably understand what you meant. However, a and c should be made clearer if written. B is probably OK as it is because of the word “vision,” so we understand that we are talking about a theory or idea.