> then that should generalize to unseen data. It's not guaranteed at all. Overcomplicated models will "overfit" the training data and generalize very poorly.

> then that should generalize to unseen data. It's not guaranteed at all. Overcomplicated models will "overfit" the training data and generalize very poorly. > some curves cannot be expressed as a polynominal You can approximate any (continuous and blah blah) curve arbitrarily well with Taylor expansions. In fact, polynomials are one of the the most common examples to demonstrate overfitting. See figure 2 on wikipedia (https://en.wikipedia.org/wiki/Overfitting https://en.wikipedia.org/wiki/Overfitting)