Reddit mentions of Skepticism: An Anthology

I wouldn't call this opposite, but Marcus Aurelius didn't think life was about pursuing pleasure while, by contrast, Epicurus thought the only objective in life was to pursue pleasure. However, Epicurus didn't define or describe pleasure in a hedonistic sense, as some might infer from the general idea that life should be about pursuing pleasure.

For example: "It is impossible to live a pleasant life without living wisely and honorably and justly, and it is impossible to live wisely and honorably and justly without living pleasantly. Whenever any one of these is lacking, when, for instance, the man is not able to live wisely, though he lives honorably and justly, it is impossible for him to live a pleasant life."

"The magnitude of pleasure reaches its limit in the removal of all pain. When such pleasure is present, so long as it is uninterrupted, there is no pain either of body or of mind or of both together."

Epicurus -- Principal Doctrines

Schopenhauer also believed that the only happiness possible in this life is the absence of pain.

Hedonism -- as a philosophy -- would identify pleasure, especially physical pleasure, as the highest good in life. And, unlike Marcus Aurelius, rejects the notion that virtue has intrinsic value. Search online for hedonistic philosophers to get a better sense.

Social Darwinism is the name given to the idea that only the fittest humans should survive and assistance should be denied to others for the sake of human progress. Some philosophers who held this view to one degree or another include Herbert Spencer and Francis Galton.

I'd highly encourage you to read Epicurus and the other epicurean philosophers, as well as Schopenhauer. The Social Darwinists can give you a philosophical approach that's very different than Marcus Aurelius, which is what you're looking for. But, Epicurus, the epicurean philosophers (http://en.m.wikipedia.org/wiki/List_of_Epicurean_philosophers), and Schopenhauer can also give you some divergent views, although not diametrically opposed.

Finally, I highly recommend the Skeptic philosophers, such as Montaigne and Diderot, if you're just getting started with studying philosophy. If you're interested, I'd suggest you start with this introductory overview/summary of the Skeptic philosophers and their doctrines:

http://www.amazon.com/Skepticism-Anthology-Richard-H-Popkin/dp/1591024749

I think studying philosophy is one of the most important, most life-changing, most interesting, and most enjoyable things any person can do. I very much wish I had started much earlier in life. It would've saved me from so much unnecessary pain and struggle and so many bad decisions.

Edit -- formatting

Best place to start for overview of skeptical philosophy from ancient through modern times: http://www.amazon.com/Skepticism-Anthology-Richard-H-Popkin/dp/1591024749.

Afterwards, select the most intriguing philosophers and read them in more detail.

Also, read anything about quantum theory and modern cosmology.

This is a great starting point that will,also amaze you:

http://www.amazon.com/The-Holographic-Universe-Revolutionary-Reality/dp/0062014102