The Soft Determinist says:

P did A freely = P's doing A had as its immediate cause a psychological state in the agent.

But if Soft Determinism is true, then these psychological states are causally determined.

So, they could not have been otherwise.

Ingenious Physiologist Example: (P 358b)

The Physiologist causes me to have certain desires (and other internal psychological states).

If I then act from these desires, I am acting freely, according to the soft determinist.

But this is surely not a free action, Taylor says. ("It is the perfect description of a puppet." P 358b)

So the Soft Determinist account of free action is mistaken.