Viruses. Virii isn't the plural of virus.
There's a YouTube channel (1) called Street Epistemology which has a guy interview members of the public and ask them if they have a belief they hold to be true such as "the supernatural exists" or "climate change is real" or "x is better than y".
He then asks them to estimate how certain they are that it's true.
Then they talk. The interviewer asks a question and makes notes, then tries to summarise the reply. He questions how they know what they think they know and at the end he asks them to again say how confident they are that what they said is true.
It's fascinating to see people actually talk about and discuss what are usually unsaid thoughts and it shows some glaring biases logical fallacies.