Pansy

The Wikipedia article on freethought mentions that the pansy was traditionally the symbol of freethought. The article explains that,

"The pansy derives its name from the French word pensée, which means "thought"; it was so named because the flower resembles a human face, and in the month of August it nods forward as if deep in thought."

The association of pansies with thought is also a part of the language of flowers nowadays largely reduced to red roses being associated with romance.

The word pansy also of course has meanings that are construed as negative by some, when it is (was) used as an insult to mean an effeminate male, implying gay. According to the Online Etymology Dictionary this connotation goes back to 1929, though it doesn't go into detail as to the context.

It is interesting that the symbol for freethought was so very soon after the so-called Golden Age of Freethought, co-opted as an insult meaning something else entirely. How the word evolved into this insult would likely be quite interesting.

Presumably those opposed to freethought used it as an insult at first merely to denote freethinkers and it became conflated with other groups they opposed due to the tendency to conflate opponents, like calling everyone a terrorist these days.

For reasons not particularly clear, gays evoke a visceral reaction for some people particularly opposed to freethought, beyond the mere contempt and hostility to thinking. So likely it was the connotation of the former that gave the insult its emotional resonance.

The connotation of insults would I suspect evolve to select for the emotional resonance. At the same time the environment was changing, as the freethought movement was ebbing, and therefore the need to insult it decreasing. This meaning would therefore be selected against.

Over time the meaning of the insult would lose its original association with freethought leaving only the vestige of thinking linked to effeminate, and with the standard misogyny of this crowd, therefore wrong. It's a theory anyway.

I am not sure if ownership of either the word pansy or the symbol of the flower is achievable or even desirable for freethought. I personally don't have much use for flowers but the symbology of this one is quite appropriate.

Just as a point of interest pansies were cultivated from wildflowers called Heartsease. The heartsease shared the association with thinking. It seems an un-usual, but welcome, symbolic pairing of head and heart. The wild part doesn't hurt either.

I also note the Wikipedia pansy page says there is such a thing as a pansy monkey flower. Perhaps this could be the symbol for the struggle of science against creationists.