  All of the definitions so far considered are definitions of positive deception, where a person “has been caused to add to his stock of false beliefs” or has been caused to continue to have a false belief (Chisholm and Feehan 1977, 144). A further objection to D1 (and D2, D3, and D4) is that it is not necessary for deception to cause a new belief or to cause to continue to have a false belief. One can deceive another person by causing the person to cease to have a true belief, or by preventing the person from acquiring a true belief. These are both cases of negative deception, according to which a person “has been caused to lose one of his true beliefs” or been prevented from gaining a true belief (Chisholm and Feehan 1977, 143–144). For example, if I intentionally distract someone who is prone to forgetting things irretrievably when distracted, in order to make that person forget something irretrievably, and, as a result, that person loses a (veridical) memory irretrievably, then I have caused him to cease to have a true belief. (In science-fiction the same result can be achieved by using a memory-erasing device, as in the neuralyzer used in the 1997 science-fiction film Men in Black). Also, if I hide a section of the newspaper from someone in order to prevent her from learning about some news item, such as an earthquake in a foreign country that harmed no-one, then I prevented her from acquiring a true belief about a distant earthquake. A modified definition of interpersonal deception that incorporates this objection is the following: