Very often I see fallacious comments somewhere, but when I look through various online lists of logical fallacies I cannot quite place which one (or more) applies.
Don't knock yourself out over it. From Aristotle onwards there have been several taxonomies of fallacy. None is definitive, not because the scholars are inept but because divisions among classes of irrational thought are sufficiently gray, and because the taxonomy reflects the domain of reasoning to which it's meant to apply. What is the difference, for example, between begging the question and circular reasoning? None, really. They're just two aspects of the same general flaw.
The typical modern name for the fallacy at hand is "guilt by association," the converse of "hasty generalization." More formally there are several concepts that apply, all intruding deeply on the other's territory. It falls into the field of categorical reasoning, which is the land of Venn diagrams and inferring from what can be known by membership in a set. Categorical deductions can almost always be phrased as classical syllogisms: a major premise, a minor premise, and a conclusion.
The government always lies.
NASA is part of the government, therefore
NASA is lying.
These sorts of syllogism can fail for two reasons. First, one or both premises can be false. And second, the syllogism may be of a "non-validating" form -- the
non sequitur. Here the major premise is untenable. In fact the government sometimes lies and sometimes tells the truth. Therefore truth-telling is not a property that may be properly generalized among all members of the government such that mere mention of the membership allows you to assert something about the property. The syllogism is of validating form, which means that if the premises are true then the conclusion must follow deductively. Validating versus non-validating forms are discerned by the proper relationships among the categories implied in the premises.
And now for something completely different, you can also examine it according to explanatory logic, which is the taxonomy of methods used to investigate and explain phenomena. Here "hasty generalization" and "guilt by association" get recast as fallacies of such things as limited depth and scope. Purported explanations are considered fallacious if they lack appropriate scope, which means they don't explain all the phenomena that legitimately seem to belong to the subject group. "You say NASA lies because it's part of the government, but I know plenty of government agencies that don't lie." It's the same flaw in reasoning, but here the explanation is revealed as lacking the implied scope: it doesn't explain all the observable behavior.
Explanations can also suffer from limited depth, meaning their proposition of cause goes no further than reflecting the observation. "You say NASA is lying about Apollo because NASA are liars." What about being NASA
makes them liars? Merely identifying membership in a set and purporting a property of that set isn't enough. Fallacies of limited depth are largely indistinguishable from circular reasoning, so both terms apply. The purported property of the set usually is a begged question, so that fallacy applies too.
So if it seems like more than one fallacy from more than one list of them applies, it probably does.
