Done properly, cognitive science is very much a science. (Any science can be done improperly to the point where it isn't really science any longer.)

The extent to which "cognitive science" deserves the title is generally somewhat greater than "political science", but somewhat less than fields that don't bother adding "science" into their name (e.g. chemistry). Cognitive science is interdisciplinary, and tends to inherit the qualities of the fields that it draws from. Since it draws from philosophy and psychology, which often have trouble being scientific, you can find philosophical/psychological cognitive science that isn't very well founded. Most of it is pretty sound, though.

For instance, UC San Diego claims the first Cognitive Science department in the world, and you can see that the publications that they're proud of tend to be very scientific: https://cogsci.ucsd.edu/research/featured%20publications.html#2018