Thanks for commenting, David!
I haven’t read Brennan’s book yet, but I have come across his name (and, consequently, some of his arguments) in other places. That said, I have to respectfully disagree with his conclusion in the quote you provided. I think his view of voting is a little too narrow. In my view, voting isn’t just about producing a single, immediate outcome. For example, if I were a committed Libertarian who voted for the LP candidate in every election, I would do so in the hopes of eventually securing federal funding for future elections, which could in turn lead to the growth necessary to transform my party into a legitimate competitor in state and national elections. And if/when that future one day comes to fruition, then all those votes that I cast for the Libertarian candidates in previous elections will suddenly matter a whole lot more than anyone ever thought they did.
In other words, IMHO, voting isn’t necessarily just about producing an immediate outcome, but also about trying to build momentum towards future outcomes that may be years or even decades away from happening. In that regard, each individual vote can act as a small but important brick in the road towards a very different future than the one we would have ended up with if everyone just bailed out on third parties altogether.
Additionally, some third-party voters may take the view that both major candidates “will bring the world further away from justice rather than closer to it.” I suspect Brennan addresses this in his book, but I’d be curious to hear how he could justify the position that a voter should vote for someone who they think will make the world a more unjust place.
In any case, thanks again for the comment, and for taking the time to read the piece! :)