In this autumn’s Vagabonds Collection, Viktor and Rolf showed a pink top covered in hundreds of buttons and framed with elaborate furls of pale pink and blue tulle; did they intend the model to look as if she was wearing a giant vulva across her chest? For me, this is the most vulgar garment (pictured below right) in an exhibition that supposedly explores the concept of vulgarity, yet is full of extremely tasteful designs.

Cheekily bottom-like, their downy skin blushing enticingly, these must be the sexiest apricots ever painted. If you held out your hand, you might just be able to touch them, there in the foreground of what is thought to be Caravaggio’s earliest surviving painting. Echoing the skin tones of a boy absorbed in the act of peeling fruit, the light highlights his hands and his downcast eyes make us voyeurs in a scene of unexpected sensuality.

The fifth edition of the highly popular Frieze Masters – the quieter sibling of the boisterous contemporary Frieze Art Fair London – is underway in Regent's Park, London. This year, the fair features 133 leading galleries from around the world. Their various displays include curated and created sections as well as solo exhibitions devoted to the works of artists such as Paula Rego (Malborough Fine Art, London), Robert Motherwell (Bernard Jacobsen Gallery, London), Lynn Chadwick (BlainSouthern, London) and Eduardo Paolozzi (Jonathan Clark Fine Art, London).

There’s something familiar about those dark, piercing eyes, but the impenetrable, mask-like countenance of Picasso’s Self-Portrait with Palette, 1906, is ultimately unknowable. In fact, the painting serves as something of a rebuke: we think we know Picasso so well, but we don’t. It’s a theme emphasised by the hang of this exhibition, and the bewildering range of styles and formats from Picasso’s early years results in a visual discord that underlines his chameleon-like tendencies.

It was inevitable that David Shrigley's breezy new sculpture for Trafalgar Square – part of the popular Fourth Plinth Programme – would be appropriated for political purposes. As the giant seven-metre-high thumbs-up Really Good was unveiled by Mayor Sadiq Khan it was greeted with a sudden downpour, but exuded a defiant post-Brexit cheery optimism. "London is open to the world," declared Khan to the sodden onlookers, welcoming immigrants, EU citizens, people of all ages and backgrounds.

While the Turner Prize shortlist can reasonably be expected to provide some sense of British art now, the extent to which British art can or should attempt to reflect a view of British life is surely a moot point. Art that is socially or politically engaged can all too easily tend towards the artless, its functionality placing it uncomfortably close to pamphleteering, with the certainties of propaganda drowning out the possibilities of art.

Gorgeous, sumptuous, thrilling: here comes Abstract Expressionism riding into town, the first major overview in London since its own contemporary heyday in the 1950s. A clunky, unappealing label for such fabulously appealing stuff, it's best just to relax and enjoy this total immersion, for colour and gesture can never have been combined to such memorable effect. Nurtured by the melting pot of New York, this was the first homegrown group of American artists, its activities destined to put New York on the international culture map, wresting the crown of art capital from Paris.

Of all the mesmerising images in William Kentridge’s major Whitechapel show, the one that lingers most, perhaps, is that of the artist himself, now turned 60, hunched and thoughtful, wandering through the studio in Johannesburg where he lives and works. He paces, meditates over a "magical" cup of coffee, imagines, draws, tears paper, works, adjusts, observes, directs – all in the gentle manner of a Buster Keaton-style silent film star. Time in this metaphoric space is thick with possibilities, under-stated humour and conundrums.

If you’ve had half an eye on BBC Four’s conceptual art week, you’ll have noticed that the old stuff is where it’s at, with Duchamp’s urinal making not one but two appearances, equalled only by Martin Creed, that other well-known, conceptual stalwart (who actually isn’t as old as he looks). The BBC would say that this is because 2016 marks the centenary of Dada, the anarchic, absurdist art movement (if a movement is what it was) that saw artists begin routinely to challenge and ridicule accepted ideas about art – what it is, why it is and what it’s for.

The wilder shores of contemporary visual art are now ephemeral or time-based: performance, installation, general carry-on and hubbub. But once upon a time – say, the 1960s – it was the nature of objects, pared down to essentials, and often made from real materials sourced from the streets, builders’ yards and shops, that startled: the idea made manifest without old-fashioned notions of the hand-made, craft or manual skill.