The package-deal fallacy (also known as false conjunction) is the logical fallacy of assuming that things often grouped together by tradition or culture must always be grouped that way. False conjunction refers to misuse of the and operator.

It is particularly common in political arguments, such as the following imagined example from the United States: "My opponent is a conservative who voted against higher taxes and welfare, therefore he will also oppose gun control and abortion." While those four positions are often grouped together as "conservative" in United States politics, a person may believe in one "conservative" idea while not believing in another.

The package-deal argument does not need to be a fallacy when used to argue that things grouped by culture and tradition are likely to be grouped in a given way.

Philosopher Ayn Rand used the term to describe a different fallacy in which essentially different concepts or ideas are “packaged” together and treated as though they are essentially similar.

Rand wrote: "'Package-dealing' is the fallacy of failing to discriminate crucial differences. It consists of treating together, as parts of a single conceptual whole or 'package,' elements which differ essentially in nature, truth-status, importance, or value."

It is important to stress that the package deal fallacy concerns solely those errors of reasoning which mistreat the essential characteristics of concepts.

Rand pointed out that, in popular usage, the term “selfishness” constitutes a package deal because it’s used as a moral evaluation, even though no such evaluation is contained or implied in the word’s meaning:

The meaning ascribed in popular usage to the word “selfishness” is not merely wrong: it represents a devastating intellectual “package-deal,” which is responsible, more than any other single factor, for the arrested moral development of mankind.