The politician has suggested that the new health-awareness campaign should be funded by an increase in taxes on cigarettes. This is because cigarette smoking causes many health problems, and, according to the politician, it is reasonable to make cigarette smokers — whose habits are responsible for many health problems — bear the cost of the campaign through taxation.

The smoker responds by stating that there is just as much evidence that eating high-fat, high-cholesterol foods causes as many health problems as smoking does. Then the smoker points out that it would be unreasonable to force the purchasers of those foods to fund the campaign. The conclusion, by implication, is that it is also unreasonable to force smokers to fund this campaign.

The smoker responds to the politician's position with a counterexample. The politician supports her claim about increasing taxes on cigarettes with two premises: first, that smoking cigarettes causes many health problems, and second, that it is "reasonable" for people whose habits cause health problems to bear the cost of the health-awareness campaign.

The smoker responds by pointing out that there is another habit — eating certain unhealthy foods — that is known to cause just as many health problems as smoking, and yet it would be unreasonable to tax purchasers of such foods for the campaign. If it would be unreasonable to fund the campaign by taxing these foods, it seems less likely to be reasonable to fund the campaign by taxing cigarettes. In other words, the smoker challenges the value judgment in the politician's second premise — that it is obviously reasonable to tax people whose habits cause negative health effects in order to fund this campaign — by providing a counterexample where, according to the smoker, it is clearly unreasonable to do so.