First; no, it's not basically theft. Theft is when you take away something without permission. They are not taking away the house, they are using it. So, it's basically not theft.
Second; this is a vacant house, it's not currently used. By not renting out houses to an affordable prices, the landlords are creating artificial scarcity. Desperate people make desperate choices, if you don't offer them any other options.
So I'm all good with that.
Even if you have a work and merit based society, you still have to provide the necessities of life to those that are unable to provide for themselves; the sick, the elderly, the unable. This includes those that do not have any abilities your society values. If you have a society that makes good use of it's people and is able to provide everyone with a position of merit, you're fine.
But as soon as you have mass of people that are not able to work and provide merit, you've got a problem. Because you have to somehow stop them from taking what they need anyway. You can do that with police and the military, but in the long run this is not stable.
Given that I don't think that we have a work and merit based society, my conclusion is that we have even more of a responsibility towards those left behind.
And of course you’re good with that because you’re a communist and communism is an extended apology for organized crime.
What is “an affordable price”? Who determines this? You? The attraction of communism is that every communist thinks they are the one philosopher-prince who will arrange everything just right yet it never works that way.
I submit to you the free market as dumb and blind and imperfectly realized as it is, is the best embodiment of what “society” actually wants. It is ironically, the closest we’ll get to the ideals of communism.
EDIT: I guess I can’t reply to @esarbe because this comment has been downvoted but for the record, I described @esarbe’ ideas as communism because that’s what they are. Yes communism is objectively evil. It has been responsible for the deaths of millions and the misery of millions more. The free market isn’t perfect — no political philosophy is — but comparatively it is light years ahead of its rivals.
What makes you think I subscribe to the ideology of communism? What makes you think it was responsible for millions of deaths (as opposed to say, tyrannical dictatorship?) What are your proofs that is - as you say - objectively evil?
Although I'd say "tyrannical dictatorship" is a necessary and sufficient condition to get to mass murders and atrocities. No need to further involve communism.
Well, property /is/ theft. You can take up a stick and say it's yours because you made it pointy. That doesn't mean it's not theft on everyone else no longer able to use the stick. Before it was a stick for everyone to use. Maybe someone decided to not make it sticky for a certain purpose. After you take it and make it yours, no one else can take it and make it theirs anymore. So, property is theft (of the common good).
I do think we as a society should ensure that all can be housed. But random squatting is not the answer.
(Also, for those who have never dealt with it, squatters tend to be intensely destructive of property.)
That's a good point. That we should indeed.