We need philosophy because philosophy teaches us to think critically about the most fundamental aspects of our world and our lives in this world. What does it mean to be happy, or to be a good person? What is reality, what is matter, or what is mind and thinking? What is the best political system or what is a good society? How do we come to know what we know? What is knowledge and truth? Without an organized analysis and understanding of such things we can't be sure that our actions will be successful. We can't know if our goals are realistic or whether our constructions will last. Nor will we be able to judge if our leaders are deceiving us or leading us down a destructive path. Without philosophy when a problem occurs, either with society or in an individual's life, one has only a feeling of discomfort or unhappiness but no real idea of what's wrong or how to fix it. Want to know how to think better? Study logic. Think there is something wrong with politics? Read what Plato's Republic, Hobbes' Leviathan, or Rousseau's Social Contract.

Perhaps you think science will answer all these questions and there is no need for anything else. Science itself is based on numerous philosophical concepts. In physics for example matter is conceptualized as a collection of tiny particles, called atoms, that interact through certain "forces" to create the objects of the world we are familiar with. This concept together with mathematics has enabled physics to produce a very successful theory of how certain parts of the world work. But this reductionist theory must be modified substantially to explain how we think or how a society works. And mathematics cannot explain mind or emotions. Philosophical analysis of science can help explain why this atomism and mathematics work better in one field than in another, and can help to create a more adequate scientific theory.

So everything we do and think about is saturated with philosophy. If we ignore philosophy and act based on partial and poorly understood remnants of various philosophies our plans and activities will have unpredictable results and problems will multiply. We literally won't know what we are doing nor how to understand when things go wrong. Or we can examine the concepts and assumptions we unconsciously live under in order to form a more complete and coherent, indeed a more realistic philosophy of life and, based on this, pursue a more successful and happy life. Or you be fucking miserable and never know why.