Yes you can - you'd be a "Western Liberal", or "Liberal Scientist" or whatever else we want to name the philosophy of thought that began with the Enlightenment. And being a "leftist" in that is 100% consistent with that.

We tend to refer to "liberals" as people on the left but in general a liberal is anyone who is consistent with liberal beliefs which include a fair amount of "conservatism" as well. However, there's quite a few folks on the right that are as illiberal as the progressives are on the left.