It starts with an explanation of what Humanism is, which I find appealing to my liberal tendencies:
"Humanism is a progressive philosophy of life that, without supernaturalism, affirms our ability and responsibility to lead ethical lives of personal fulfillment that aspire to the greater good of humanity.
The lifestance of Humanism—guided by reason, inspired by compassion, and informed by experience—encourages us to live life well and fully. It evolved through the ages and continues to develop through the efforts of thoughtful people who recognize that values and ideals, however carefully wrought, are subject to change as our knowledge and understandings advance."
What I like about the manifesto is that it does not set things in stone. I do not get the sense that "this is what Humanism is, as it was in the beginning, now and forever shall be, world without end, Amen." It is continuously growing. If you read the previous two manifestos you'll see what I mean. It is an organic philosophy that, like water taking on the shape of whatever container it is poured into even as it retains its wateriness, adapts to the changes of life even as it retains its basic nature.
I also do not find it to be incompatible with Buddhism* - while it is by no means a "Buddhist" school of thought, the following affirmations below do not run counter to Buddhist teachings:
"This document is part of an ongoing effort to manifest in clear and positive terms the conceptual boundaries of Humanism, not what we must believe but a consensus of what we do believe. It is in this sense that we affirm the following:
Knowledge of the world is derived by observation, experimentation, and rational analysis.
Humans are an integral part of nature, the result of unguided evolutionary change.
Ethical values are derived from human need and interest as tested by experience.
Life's fulfillment emerges from individual participation in the service of humane ideals."
Well, except maybe for that last line. But not so much in the sense that Buddhism argues the opposite - that Life's fulfillment does not emerge from "individual participation in the service of humane ideals" - as in the sense that fulfillment isn't the point as far as Buddhism is concerned. That being said, there is nothing wrong with wanting to participate in the service of humane ideals. I, for one, choose to participate in this. Just because life is impermanent and life is dukkha (I prefer to use this term instead of the usual English translation into "suffering" because of my Catholic upbringing - the word suffering brings the image of crucifixion to my mind) doesn't mean that it is wrong and pointless to work to improve the quality of human life. Let's continue:
"Humans are social by nature and find meaning in relationships.
Working to benefit society maximizes individual happiness.
Humanists are concerned for the well being of all, are committed to diversity, and respect those of differing yet humane views. We work to uphold the equal enjoyment of human rights and civil liberties in an open, secular society and maintain it is a civic duty to participate in the democratic process and a planetary duty to protect nature's integrity, diversity, and beauty in a secure, sustainable manner.
Thus engaged in the flow of life, we aspire to this vision with the informed conviction that humanity has the ability to progress toward its highest ideals. The responsibility for our lives and the kind of world in which we live is ours and ours alone."
Here, Buddhism and Humanism agree. Yes of course there are things and events that occur beyond our control. But although we do not have full control (and we shouldn't even bother trying to have full control if we want to keep our sanity), we do have some degree of control. We are not responsible for the uncontrollable events in our lives - we are however, responsible for how we choose to live.
To read the Manifesto III in full, click on this sentence.
*A disclaimer is necessary here: I am speaking here out of my own understanding of Buddhism. I do not represent the whole of Buddhism, and other Buddhists may disagree with me.