company is and how nicely the system works. A student asks him "Is it true that you and your company are selling weapons to third world rulers who use those arms against their own people?" and the businessman replies "is it true that your university gets funding by the same company that you are claiming is selling guns to those countries? You are not a white dove either". The ad hominem accusation of the student is relevant to the narrative the businessman tries to project thus not fallacious. On the other hand, the attack on the student (that is, the student being inconsistent) is irrelevant to the opening narrative. So the businessman's tu quoque response is fallacious. Canadian philosopher Christopher Tindale approaches somewhat different the tu quoque fallacy. According to Tindale, a tu quoque fallacy appears when a response to an argument is made on the history of the arguer. This argument is also invalid because it does not disprove the premise; if the premise is true, then source A may be a hypocrite or even changed their mind, but this does not make the statement less credible from a logical perspective. A common example, given by Tindale, is when a doctor advises a patient to lose weight, but the patient argues that there is no need for him to go on a diet because the doctor is also overweight. Circumstantial Circumstantial ad hominem points out that someone is in circumstances (for instance, their job, wealth, property, or relations) such that they are disposed to take a particular position. It constitutes an attack on the bias of a source. As with other types of ad hominem attack, circumstantial attack could be fallacious or not. It could be fallacious because a disposition to make a certain argument does not make the argument invalid; this overlaps with the genetic fallacy (an argument that a claim is incorrect due to its source). But it also may be a sound argument, if the premises are correct and the bias is relevant to the argument. A simple example is: a father may tell his daughter not to start smoking because she will damage her health, and she may point out that he is or was a smoker. This does not alter the fact that smoking might cause various diseases. Her father's inconsistency is not a proper reason to reject his claim. Philosopher and pundit on