Why do we need the chemical level in addition to the physical level?

• A. Because physics doesn't tell us much about human behaviour
• B. Because physics fully explains behavior
• C. Because chemical reactions dominate all neural processes
• D. Because the physical level is sufficient

Answer: (A)

Behavior requires both physical and chemical levels of analysis. The physical level explains how the brain’s structure and electrical signals carry information—the firing of neurons, the timing of spikes, and how networks transmit impulses. But chemical signaling governs how those electrical signals are produced, transmitted, and modulated: neurotransmitters released at synapses, receptors that listen for those chemicals, and neuromodulators that change how strongly or quickly networks respond. This chemical layer shapes learning, memory, mood, motivation, and perception, and it explains why drugs or hormonal states can alter behavior even when the underlying electrical framework is the same. So physics alone doesn’t tell us much about human behavior because it doesn’t account for how chemical processes modify neural communication and network dynamics. The other statements either overstate physics’ reach or ignore the crucial role of chemical signaling in behavior.