What Fallacies Is Painting A Group Because of Some Bad Apples?

Have a look at nutpicking fallacy . There is debate over how many nuts make the group as a whole justifiably nutty.

The following is my opinionated rant and is only somewhat related to this post, so be forewarned.

As mentioned, we in the US have seen something similar with the Jan 6th attack. This is also similar to the racial riots/protests that took place all around the country previously. A group of protesters/rioters of any significant size are rarely ubiquitous. Just like the general population, there are extreme elements, and those extreme elements are loud and difficult to ignore. The "innocent protester" needs to realize that they provide both cover and legitimacy for the extreme element that cause serious damage. They need to consider this a cost of exercising their right to protest. It may still be worth it to them, or when considering their role in a far more destructive and nefarious plan, they may reconsider their "benign" participation. The bottom line is, as a group, each member is far less "legitimate" because of their role in providing cover to the extreme elements. The moment they are aware of what the "protest" has become, they should bow out; otherwise, they bear some responsibility for the harm the extremists cause.

... and another "chime in" from Ottawa.  Criticizing a larger group because of actions of a minority can certainly be considered as the nutpicking fallacy .  (From my observations, racist symbols, signs and actions certainly were present, but in relatively small numbers compared to the other signs and actions on display.)  Whether one supports or opposes the activities going on in the streets of Ottawa, so far, I haven't seen much evidence that overall those involved are all (or even mostly) right wing white supremists with racist symbols.  One could argue that the comments were ad hominem (guilt by association). (However, I'm not sure if guilt by association is intended to be unidirectional or if it can function in either direction.)  Most examples of guilt by association I've seen were cases where an individual is (perhaps wrongly) viewed negatively because of association with a group that's considered in a negative light – this example seems to have turned the association around ... the group is viewed negatively because of association with individuals that are negatively-viewed.  

As I understood Mr. Trudeau's comments (from what I heard and read as edited versions on TV, Radio, and print media), I agree with Ed F's assessment in that he attempted to delegitimize the entire group of protesters because of a small group.  That's not a particularly strong argument!

Clearly, as Prime Minister, he needs to present reasons why those assembled on the streets of Ottawa should disband; however, I don't see the presence of a comparatively small number of negative symbols as the best (or even a good) argument – there are lots of others justifications he could have used that would have directly addressed the issue more strongly.