The author makes the mistake of equivocating rationalizing with rationalism. "For example, suppose that (1) watching a scary movie usually makes a person fearf

The author makes the mistake of equivocating rationalizing with rationalism. "For example, suppose that (1) watching a scary movie usually makes a person fearful or anxious, and that (2) being fearful or anxious usually causes the person’s heart rate to increase. Applying logic we would conclude, therefore, that watching a scary movie raises a person’s heart rate." This is why we say things like "sufficient but not necessary" or other nice things like this. The author is ambiguous in this example and logic requires rigor, not equivocation.