Smart notes that, "I shall not deal with all Ziff's reasons, but will concentrate on certain of them to be found in Section 9 of his article, which I take to be crucial.

Robots do not feel because:

"The way a robot acts (in a specified context) depends primarily on how we programed it to act." For the sake of simplicity I introduce the notion of Nature to represent the sum of causes going towards the creation of a human being considered as beginning with conception or at any later time in his life. What is wrong, for the determinist, in saying that the way a man acts, in a specified context, depends primarily on how nature programs him to act? Subtle programs, of course; much subtler than computer programs, but the subtle cell circuits still determine the way I act, given a situation" (N. Smart, 1959, p. 107).

Source: Smart, Ninian. 1959. Professor Ziff on Robots. Analysis, Vol. XIX, No. 3. Reprinted in Minds and Machines (1964). Alan Ross (Ed.), pp. 106-8.