We are all familiar with thermostats — devices we use to regulate temperature, typically in central heating and air conditioning systems, as well as ovens, refrigerators, and water heaters. But did you know that our bodies also contain their own thermostat, which is responsible for maintaining our body temperature at the optimal level?

I recently read a paper from 2007 by two plant geneticists, Wolf-Ekkehard Lönnig and Heinz-Albert Becker, from the Max-Planck-Institute for Plant Breeding Research in Cologne, Germany. The paper presents a review of carnivorous plants, which, by employing “enormously different and ingenious trap mechanisms,” ensnare and digest insects.

The development of an egg cell and its activation in response to encountering a sperm cell exhibit exquisite design, being contingent upon multiple mutually dependent processes, all of which are needed for successful reproduction. When considered in conjunction with the incredible engineering features of the sperm cell and the seminal fluid, it would seem to put the thesis of design almost beyond question.

Several different structural components are necessary for the vertebrate sense of hearing. It strains credulity to suppose that an unguided process of random variation sifted by natural selection could assemble such a delicately arranged system. It instead points to a cause with foresight.

Muscle contraction — which we so easily take for granted — is an incredibly complex and elegant process, involving incredible engineering and design. To contend that the phenomenon of muscle contraction arose through a blind and undirected process, one tiny Darwinian step after the other, seems to me to strain credulity.

Muscle is one of the most fundamental of animal tissues. It is muscles that animate our bodies — allowing us to move, stand upright, breathe, and even speak. Muscles are precisely the sort of thing that we might expect a designer of embodied intelligent beings to produce.

Here, I will address an objection to irreducible complexity I’ve encountered that attempts to handwave the argument away as though I were missing something obvious. This is, in my judgment, one of the weakest objections to irreducible complexity, though it persists as a popular one — even among experts. It is therefore worth commenting on. I will use as case examples two responses to recent articles of mine.

As in the case of so many physiological processes, the male erection and ejaculation reflex requires multiple processes to function in unison to achieve a higher-level objective — in this instance, depositing seminal fluid, containing millions of sperm cells, in the female vaginal cavity.