Agency is an interesting topic. I tend to believe we have free will and free agency.

You posed this statement:

Science, at least what it knows about free will, says different… As far as they are concerned all human behavior can be explained by the laws of cause and effect.

If you are referring to sciences like psychology and sociology, it is a bold claim to say all of human behavior can be explained of such. Suppose the case of Pavlov's Dog (classical conditioning), and knowing humans respond similarly, we respond automatically to stimuli. However, because humans are rational, it is possible in which we can make the decision to not do something. For example, when you are hungry, you have the psychological desire to eat. However, you still possess the ability to not eat.

I think a good point for free will is that we can think of something as well as the negative form of it. We can perform an act even if it is against our best interest. You can argue that we are pre-destined to consider both, but if we are capable of preforming both, what is the difference of having no free will or free will?

I personally study philosophy of science, so you can take what I said here with a grain of salt. But I thought it was an interesting topic I can contribute to.