Ash,
My initial reaction was one of trying to understand Thanos, and questioning myself if I had this character all wrong because at the end Thanos wasn't satisfied with his decision. He honestly felt remorseful for his decision but in his mind face with two bad decision, he choose the lesser evil. That was my initial thought looking at the movie thinking of the end and looking back. Do the means justify the end? To your point, it really depends on the person. A few points I want to make.
First, in my younger days I thought the means justified the end. I would purposely do bad things to manipulate people to do what is best for them. In fact, I learned this first from my parents. The carrot or the stick principles is such means. As I grew more mature in my thinking and understanding of philosophy and my moral principles, I changed to the means does not justify the end. I firmly believe good can only be achieve through good means and under no circumstances should evil action be done. Principles matter and is all we have. I reserve one condition were killing is acceptable, and that is self defense. Under this condition, perhaps Thanos can argue for this too. If others want to read the beginnings of the means justifies the end, the Prince by Machiavelli sparked the great debate during the Renaissance. You can download for free and enjoy this amazing book. It teaches that leaders are sometime require to use evil means to control the mass, or achieve good means, and it is the burden of leadership to act. Hence, only Thanos had the fortitude and gumption to take the proper action to save the Universe through sacrificing many. In the world of Corporate America where there is downsizing, M&A, and etc... America corporation will lay off people to make the books. Livelihood are sacrificed to hit the numbers and enrich the rich and keep most people employed. No leader likes to fire people but they do...
Second, the person most like Thanos is a philosopher named Mao Tse Tung. Mao watched as his people were raped and pillaged by foreigner over and over and he could no longer stand the fracture state of China. Mao vowed something must be done and a movement begin. This philosopher eventually turned into political leader. In the people's revolution to unified China, over 30 million Chinese people were murdered/killed. Today, many Chinese people remember the lives loss to during the cultural revolution and say it is worth it. To those who benefited from the loss, they cheer Mao as a great hero. To those who families were torn and lost, they cursed Mao. Who is right?
Third, if you have not heard of these two philosophers then it might be an interesting time listening to them. The Chinese Political Philosopher Zhang WeiWei argues that the West cannot understand the sorrow and situation China was in during the people's revolution and therefore is not in a position to judge China's leader during the people's revolution or the leaders today. His philosophy reminds me of another philosopher who states that modern people cannot judge ancient people as being barbaric because norms have changed and people should be judged to the norms of their time. Zhang makes compelling argument that justifies China PRC cost. Zhang argues for pragmatism and utilitarian approach. Harvard Professor, Michael Sandel teaches the Harvard Justice class online free on youtube. His course gives us deeper insight and clarity into the concept of justice and morality and we can choose who we are. Do the means justify the end???
I, too, struggled with this question after seeing the movie. Initially I thought I was going to hate Thanos. He is, after all, the antagonist of the movie. But as I watched, I started feeling uncomfortable because I didn't hate Thanos. He showed compassion! He showed kindness! He loved! Aren't villains supposed to be evil and devoid of all the soft emotions that we tend to associate with the "good" guys? I was torn and confused, unsure about how to feel about him. And I sense that this ambivalence that we feel about Thanos was done deliberately by the screenwriters and director.
Before I go any further, I will add that all my observations here are based solely on the movie and not the comic books.
Thanos's compassion: When Scarlet Witch killed Vision, Thanos showed compassion and empathy for her. Instead of being annoyed or angered, he said something like "I understand your pain, my child." Why would a villain show understanding to his enemy's pain?
Thanos's kindness: When Thanos took young Gamora away from her people, he distracted her from seeing the slaughter of her people. He gave her his knife and showed her how to balance it on her finger (the theme of perfect balance is introduced here, showing his mindset). Even when she turned to look, he turned her back and wouldn't let her see what was happening. I thought this was kind of him. A crueler master would have made her look upon the destruction of her people in order to break her spirit.
Thanos's love: I always wondered why Thanos didn't go after Gamora after she stole the infinity stone from him. He could've easily tracked her down and punished her for betraying him. Yet he let her go.
So to answer the question: Was Thanos a good guy? I suppose it depends on your definition of morality. At the most basic core of the matter, can you justify killing half of the universe's population in order to save the other half? Obviously Thanos does. He witnessed the destruction of his home planet because his leaders didn't want to follow his suggestion of culling the population. In his mind, the means justifies the end. He told Gamora that the other half of the population on her home planet are thriving. No child is going hungry. To him, this end result is justified. He sees himself as righteous in his mission, and he is willing to sacrifice everything to attain it. Even if it breaks his heart. Some might call this crazy. Others say it's the true mark of a leader. How many can make hard decisions like this, and still hold true to their vision?
So whether Thanos is good or bad is up to each person to decide. Personally, I understand why he goes to such extremes to put the universe back in balance. I don't hate him for it. I even admire his strength, his focus, and the sacrifices he made in order to make the universe a better place. It takes true strength of mind and spirit to do what he did, and to still show empathy to his enemy. He exhibits kindness but he's also cruel. He loves yet he sacrifices that love for what he thinks is a better world. In his mind, his intentions are good, even if his methods are not. I respect that.
But I also respect what Captain America said. All life is precious. Life should be treasured and guarded, not sacrificed. It's the classic philosophical question: would you rather one person die to save many, or would you rather save that one person and doom everyone else?
In contrast to Thanos, let's also look at Scarlet Witch who also sacrificed someone she loved, also with the hope of saving the universe. How is she different from Thanos? Is there actually a difference? I think there is. Because even with her sacrifice of killing Vision and destroying the mind stone, even though in effect she did the same thing that Thanos did, her aim was to ultimately save all lives because all lives are precious. That is a direct contrast to Thanos's view.
While watching the movie I felt troubled to be conflicted about Thanos, that I couldn't just hate him as the bad guy. Now, after some time to process it, I think it's actually good to feel that way. People are multifaceted and complex. So it makes sense that emotions are also that way. Sometimes things are just not simple, and sometimes simplicity is also a blessing. What's also simple is the message I gleaned from the movie, one that resonates within my soul, that yes, life is precious.