There is a port to Python 3, but it's (a) a separate project, (b) still in alpha, and (c) not yet installable via pip. As the homepage says, 'NLTK requires Python versions 2.6-2.7.' 3.3 is not 2.6-2.7. If you want to learn about how to figure out what's where and how PATH finds things, how Python/easy_install/pip decides where to put things that it installs, where your multiple site-packages are, how pig-resources works, etc., then go learn all of that and you will be able to make this work. And this is exactly the kind of problem you get by having two Python 2.7 versions. Most likely the top pip on your PATH is the one that goes with Apple's Python 2.7, but the top python on your PATH is the one that goes with your other 2.7. How can I install NLTK … through the Terminal using Python 2.7.5? But if you search this site or Google with the appropriate information, like 'uninstall ActiveState Python Mac', you'll find them pretty quickly on your own. Since you haven't said how you installed 2.7.5, I can't give any specific instructions. If you used a package manager like brew or port, it will have an uninstall command if you used an installer package, it may or may not have come with an uninstaller in some cases, you may have to manually track down and delete everything. So, how do you get rid of your extra Python 2.7.5? That depends entirely on how you installed it. Just stick with Apple's 2.7.5 (Mavericks) or 2.7.2 (Snow Leopard through Mountain Lion).

Unless you really need to do it for some reason, don't put yourself through the headache. Having Python 2.x.y and 2.x.z in parallel (or two different 2.x.y) is a big problem. Having Python 2.x and 2.y or 3.x and 3.y in parallel is fine, as long as you remember to always use the specific versions of everything (e.g., run python2.7 instead of python, or pip-3.3 instead of pip3).

Having Python 2.x and 3.x in parallel is fine. How can I sort the mess of having too many Python versions?

Install eclipse for python on mac