If you disagree with the statement, "guns don't kill people, people do," then you agree with McLuhan's maxim of the medium being the message and that there is no such thing as an unbiased tool.
You can use a hammer to screw and a screw to hammer, but the biases for their respective uses are embedded in their affordances. McLuhan argues that the same can be said for any tool, whether it's a binky or a bomb.
For the record, I disagree with McLuhan, but perhaps I don't fully understand his argument.