The problem with Russell's argument arises when he states "we must know that only A causes B." (Russell, 248) We have no reason to accept that only A causes B. Russell does not explain the concept of reflexes in his argument. A reflex is “an action performed in response to a stimulus and without conscious thought.” (Reflex) You have the thought that your reflex will be stimulated but this does not cause the reflex to react. There is an action that must occur to cause the reflex reaction. When a reflex is stimulated, you don't need to think about the action taking place. Involuntary bodily functions also run counter to the postulate of the existence of other minds. We don't need to think about the involuntary bodily functions happening within us to know that they are working. To be alive, your brain controls more actions than you could imagine. If you had to think about every time your heart beat or every time you breathed, you would probably forget to do one or both of those two and die. This leads to great uncertainty as to whether Russell's new postulate is true or not. Faced with the question of this uncertainty, he responds by saying: “It is not necessary for us to know this with certainty; it is sufficient if it is highly probable. (Russell, 249) The only way to save this position would be for Russell to distinguish between the actions he was talking about in his postulate A causes B. If Russell had clarified that only voluntary actions caused by thought are included in the postulate of the existence of other minds, then he would have strengthened his argument. He leaves doubt in his argument when he refers to all analogous visible human movements. We don't think about blinking, breathing or pumping our blood.