In what sense is critical thinking like a "vaccination," and why is that its practical value?

It works as an inoculation against manipulation and disinformation — exposure to how bad arguments work builds resistance to dogmatism and ideology.

Budelacci frames critical thinking as a protective immunity ("Impfschutz"). Just as a vaccine trains the body to recognise and resist a pathogen, learning to spot fallacies, propaganda techniques and ideological framing trains the mind to resist them when they appear in the wild. Concretely, it helps you:

• gauge the truth-value of claims more accurately, and
• take part in debate constructively — weighing different perspectives and finding compromise.

So its payoff is double: it strengthens the individual (clearer judgement, harder to manipulate) and it strengthens democracy (citizens who can deliberate rather than be herded).