Propensity, predilection and proclivity all have the meaning of tendency, so what's the difference? Are they interchangeable?
Predilection means tendency to favor, not just tendency:
a tendency to think favorably of something in particular; partiality; preference: a predilection for Bach.
Propensity: a natural inclination or tendency: a propensity to drink too much.
Proclivity: natural or habitual inclination or tendency; propensity; predisposition: a proclivity to meticulousness.
So while propensity and proclivity are close synonyms, and interchangeable, predilection means something different, and should not be used as a synonym.
There is one major difference between propensity and proclivity, and that is popularity:
Proclivity to me sounds more scholarly than propensity, maybe just because not many people use it.
I'm not providing any supporting evidence to this claim, but I am simply wondering if anybody uses propensity and tendency in the same way that I do. I've always used propensity to describe something like a more obvious or recognizable tendency, or a person is perhaps more indulgent in some kind of activity than the word "tendency" would suggest, e.g. "he has a propensity for violence" OR "They have a propensity to overeat". Conversely, I use tendency where an action or emotion etc is passive or implicit, e.g. "She has a tendency to forget things". So the way I use those two words personally is significantly different. Does anybody else feel the same way?
P.S. I lied earlier, I will attach some supporting evidence.
When you look at the origins and different definitions of these two words, propensity does seem to have a stronger meaning.
Predilection means a natural preference for something. It’s a strong liking deriving from one’s temperament or experience; so when you prefer something, there is a sense of something else that is less interesting or intriguing from your point of view that you might have experienced before or you just don’t like it and you do not prefer. A predilection for Bach, for example, you prefer Bach to Beethoven, or maybe Chopin, because you’ve experienced all of them before or you like Bach more than Beethoven and Chopin because his style suited you and you would enjoy Bach’s masterpieces again and again. Propensity on the other hand, is a natural inclination or tendency. The word doesn’t have a sense of comparison. It can just be a habit that has turned inveterate. For instance, a propensity to drink too much, it means you do it because it might be a habit that is incorrigible. You drink too much, because you like to drink, not because you prefer drink to eat.